PSYC101 Introduction to Psychology Notes PDF

PSYC101[Week 1] 1.1 Psychology's Philosophical Roots WHAT IS PSYCHOLOGY? Psyche: soul, mind Logos: knowledge/to study Psychology: The scientific study of mind and behaviour Mind: refers to a set of private events that happen inside a person o The thoughts and feelings that we experience at every moment but that no one else can see o Set of subjective events Perceptions and memories Thoughts an feelings Behaviour: a set of public events o The things we say and do that can potentially be observed by others DUALISM and MATERIALISM René Descartes (1956-1650) a dualist who embraced philosophical dualism: -> which is the view that mind and body are fundamentally different things Philosophical materialism: the view that all mental phenomena are reducible to physical phenomena o Thomas Hobbes (1588-1679) a materialist, argued that the mind and body aren't fundamentally different things Rather the mind IS what the brain DOES The brain is a physical is a physical object whose activity is known as "the mind," therefore, all mental phenomena ---- every thought and feeling, sight & sound--- - is the result of some physical activity in the physical brain Most psychologists embrace materialism o They believe that all mental phenomena are ultimately explainable in terms of the physical processes that produce them REALISM and IDEALISM Philosophical realism: the view that perceptions of the physical world are produced entirely by information from the sensory organs. o The brain uses only one information to produce your perception Philosophers such as Immanuel Kant (724-1804) saw a major flaw in realism Kant suggested that our perceptions of the world are less like photographs and more like paintings Philosophical idealism: the view that perceptions of the physical world are the brain's interpretation of information from the sensory organs o Our perception of the world is an inference-- our brain's best guess about what's likely to be out there Modern psychology has come strongly to the side of idealism PSYC101[Week 1] EMPIRICISM and NATIVISM Philosophical empiricism: the view that all knowledge is acquired through experience o John Locke believed that a newborn baby is a tabula rasa- "Blank slate" upon which experience writes its own story Philosophical nativism: the view that some knowledge is innate rather than acquired o Immanuel Kant argued that human beings must be born with some basic knowledge of the world that allows them to acquire additional knowledge of the world. o For Kant these basic knowledges were concepts such as space, time, causality and number. o Most modern psychologists embrace some version of nativism 1.2 The late 1800's: Towards a Science of the Mind Psychologist Hermann Ebbinghaus (1908) remarked that " psychology has a long past but short history. o Its history as an independent science began a mere 150 or so years ago, when a few German scientists began to wonder whether the methods of the physical and natural sciences might be used to study the human mind STRUCTERALISM: What is the mind like? o Hermann von Helmholtz (1821-1894) was best known in psychology for major contributions to our understanding of vision and hearing. He would ask people to close their eyes and respond quickly as possible when he touched different parts of their legs. He recorded each person's reaction time: Amount of time between the onset of a stimulus and a person's response to that stimulus By carefully measuring a person's rxn on different parts of their body and comparing the two measurement, he was able to calculate the speed at which nerves transmit information oWilliam Wundt (1832-1920) approach to understanding the mind is known as : Structuralism: an approach to psychology that attempted to isolate and analyze the mind's basic elements o Edward Titchener (1867-1927) pioneered a technique he called "systematic self- observation" known now as: Introspection: the analysis of subjective experience by trained observers The process that involves looking inward to examine one's own thoughts and emotions o Self-examination, analyzing yourself Problem with introspection That each person 's inner experience was an inherently private event, there was no way to tell if a person's description of her experience accurate, and no way to tell if her experience was the same or different as others: TOO SUBJECTIVE Problem of structuralism The methods that some of its influential followers used PSYC101[Week 1] FUNCTIONALISM: What is the mind for? William James (1842-1910) o He had become one of the founders of the new discipline of psychology. o Professor at Harvard University and devoted the rest of his life to philosophy and psychology o Wrote The Principles of Psychology; one of the most influential books ever written on the subject o thought psychologists should worry less about what mental life is like and more about what it was for Together with John Dewey (1859-1952) and James Angell (1869-1949), a new approach called functionalism was developed Functionalism: an approach to psychology that emphasized the adaptive significance of mental processes (the function/purpose of consciousness) o Functionalism "inherited its physical body from German experimentalism, but got its mind from Darwin" o Charles Darwin (1809-1882) was a naturalist, who proposed the principle of natural selection Natural Section: the process by which the specific attributes that promote an organism's survival and reproduction become more prevalent in the population over time. i.e Evolution Shaping the human body William James reasoned that natural sections should also have shaped the mind James wrote in 1892 "Consciousness has in all probability been evolved, like all other functions, for a use --it is to the highest degree improbable a priori that it should have no use." The mind serves as a function, the task for psychologists was to figure out what that function was 1.3 The Early 1900s: Psychoanalysis and Behaviourism Psychoanalysis: the mind does not know itself Hysteria: is a loss of function that has no obvious physical origin. Unconscious: is the part of the mind that contains information of which people are not aware. Sigmund Freud (1856-1938), felt confident that these exiled or "repressed" memories were the source of his patients hysterical symptoms. o He developed an elaborate theory of the mind known as Psychoanalytic theory; a general theory that emphasizes the influence of the unconscious on feelings, thought, and behaviours. o Freud believed that the only way to confront these denizens of the deep was through Psychoanalysis: a therapy that aims to give people insight into the content of their unconscious minds Behaviourism: The Mind Does Not Matter John Broadus Watson (1878-1958) felt that if psychology wanted to become a real science, it should limit itself to studying the things people do rather than the things they claim to think and feel. o Watson called this idea Behaviourism: an approach to psychology that restricts scientific inquiry to observable behaviour. PSYC101[Week 1] He argued, that psychology should be the scientific study of the relationship between Stimuli and responses. By 1930s, experimental psychology was behaviourism John Watson thought behaviourism would make psychology an objective science The american psychologists who resisted behaviourism in the early 1900's were social psychologists. Burrhus Frederick Skinner (1904-1990) o Principle of reinforcement: a principle state that any behaviour that is rewarded will be repeated and any behaviour that isnt won't o By the 1940's behaviorism was viewed as the one right way to do psychological science. o Skinner claimed that free will was an illusion, Behaviour was nothing more than the sum of its consequence. 1.4 The Early 1900s: Resistance to behaviourism Gestalt Psychology and Developmental Psychology Gestalt psychology: an approach to psychology that emphasized the way in which the mind creates perceptual experience. Jean Piaget (1896-1980) along with Lev Vygotsky (1896-1934) helped create an area of experimental psychology called : o Developmental psychology: the study of the ways in which psychological phenomena change over the life span. Social Psychology Kurt Lewin (1890-1947) had a simple idea: o Behaviour is not a function of the environment, but of the person's subjective construal of the environment Responses do not depend on stimuli, as the behviourists claimed; rather, they depend on how people think about those stimuli Lewin gave birth to a new area of experimental psychology called: o Social psychology: the study of the causes and consequences of sociality o Social psychologist studied similarly "mentalistic" phenomena: Carl Hovland (1912-1961) and Irving Janis (1918-1990) studied how people people persuade each other to change their beliefs Gordon Allport (1897-1967) studied hoe people form stereotypes Muzafer Sherif (1906-1988) studied how people create identities based on their social groups Fritz Heider (1896-1988) studied how people infer each other's intentions 1.5 The Late 1900s: The cognitive Revolution Liguist Noam Chomsky critiqued Skinner's book, arguing that behaviourist principles could never explain some of the most obvious features of language learning o Using formal mathematical logic, Chomsky showed that a purely behaviourist account of learning could never explain how children learn grammar PSYC101[Week 1] Cognitive Psychology Cognitive psychology: is the study of human information processing With the digital computer as their liberator, existence proof, and guiding metaphor, psychologists of the 1950s and 1960s suddenly felt emboldened to study topics that everyone but the dissidents had ignored for decades o Donald Broadbent (1926-1993) began studying how people shift their attention from one stimulus to another o George Miller (1920-2012) began studying how people expand their capacity to process information by combining it into chunks o Jerome Bruner (1915-2016) began studying how a person's desires can shape their perceptions of physical objects o This dramatic shift in psychology's orientation came to be known as the "The Cognitive Revolution" Evolutionary Psychology Evolutionary Psychology: the study of the ways in which the human mind has been shaped by natural selection o Donald Symons (b. 1942) began studying gender differences in sexual promiscuity; o Leda Cosmides (b. 1957) and John Tooby (b. 1952) began studying how people detect cheaters in a social exchange; o David Buss (b. 1953) began to study how people select their ideal mate; Evolutionary psychology "is not a specific subfield of psychology, such as the study vision, reasoning, or social behaviour. o It is a way of thinking about psychology that can be applied to any topic within it After the Revolution In the aftermath of the cognitive revolution , most modern psychologists are concerned with some aspect of mental life, and most agree that the mental life is influenced by its evolutionary origins Like the structuralists, cognitive psychologists now ask what the mind is like, Like the functionalists evolutionary psychologists now ask what the mind is for 1.6 The Early 2000s: New Frontiers Neuroscience The mind is what the brain does Psychologists learned from brains that were damaged from nature but also learned from brains that they damage themselves o Paul Broca (1824-1880) concluded hat the ability to speak somehow depended on this particular region--this region is today called Broca's Area. o Karl Lashley (1890-1958) concluded that learning is not "localized" or tied to a specific brain area in the same way that language seemed to be. New technologies allowed psychologists to observe the undamaged brain in action. Ex. The functional magnetic resonance imaging (fMRI): which produces brain scans o These scans were maps showing the amount of blood that was flowing in different parts of a person's brain at a particular moment in time o Because neural activity requires oxygen and blood supplies it, These scans tell us which areas of the brain were processing the most information at any particular time. PSYC101[Week 1] o For example, people using their hands to speak ASL show increased neural activity in the same region of the left hemisphere that Broca identified. The advent of the fMRI and other technologies has given birth to 2 new areas of psychology: o Cognitive neuroscience: the study of the relationship between the brain and the mind ( esp. in humans) o Behavioural Neuroscience: the study of the relationship between the brain and behaviour (esp. in non-human animals) Montreal' A birthplace of cognitive neuroscience o Donald Olding Hebb (1904-1985) wanted to study the effects on psychological processes of the very specific brain removals Penfield was producing. 1948, Hebb was chair of the department of psychology at McGill His ideas are now the basis of our understanding of how the physical structure of the brain changes with experience o Wilder Penfield (1891-1976) founded the Montreal Neurological Institute in the 1920s, and pioneered the surgical removal of brain tissue to relieve seizure disorders--known as "the Montreal procedure" o Brenda Milner (1918-) is best known for the discovery of the brain basis of long term memory Cultural Psychology Culture: refers to the values, traditions, and beliefs that are shared by a particular group of people, nationality, ethnicity and also by age, sexual orientation, religion, occupation. Cultural Psychology: is the study of how culture influences mental life PSYC102[Week 1] 1.1 Empiricism: How to Know Stuff x Were Two types of doctor: o Dogmatists (from dogmatikos meaning "belief") x Thought the best way to understand illness was to develop theories of the body's function x Today the word dogmatism is used to describe people's tendency to cling to their beliefs and assumptions o Empiricists (from empeirikos, meaning "experience") x Thought the best way was to watch sick people and see what happened. x Empiricism: to describe the belief that accurate knowledge can be acquired through observation THE SCIENTIFIC METHOD x Empiricism is the backbone of the scientific method o Scientific Method: a procedure for using empirical evidence to establish facts Develop a theory Derive a falsifiable hypothesis Test the hypothesis but observing the world i.e. Gathering empirical evidence x Theories: hypothetical explanations of natural phenomena o Theories are collections of ideas abt how some part of the world works o Explanation of how something in the natural world works and why it works that way o A good theory: Makes specific predictions about what we should observe in the world if the theory is true If …….. Then …. SHOULD….. That "should" statement is known as the hypothesis Gives rise to hypotheses that can be falsified x Hypothesis: a FALSIFIABLE prediction made by a theory o Hypotheses are predictions on what should happen in the world if we do something o Must be able to prove them wrong x Although a theory can be proven wrong, it can never be proven right o Observations that’s are consistent with a theory can increase our confidence that the theory is right, but they can never make us absolutely sure it is right EMPIRICAL METHOD x Empirical method: a set of rules and techniques for observation o Using observation (empiricism= experience) as the primary method of knowledge acquisition, as opposed to authority/dogma, or pure intuition o Collecting data using observation (w/ special rules and tools) o Creating hypotheses that are falsifiable x The word Methods refers to technologies that enhance the powers of the senses. x Human beings have 3 qualities that make them more difficult to study 1. People are highly complex 2. People are highly Variable No two people ever do, say, think, or feel exactly the same thing under the exact same circumstances, 3. People are highly Reactive People tend to think, feel, and act differently when they are, or are not being observed. x Psychologists have developed 2 methods to study humans: 1. Methods of Observation Allow them to determine what people do 2. Methods of explanation Allow them to determine why people do it PSYC102[Week 1] 1.2 Methods of Observation: Finding Out What People Do x Everyday observation are often Inconsistent o The same object can appear differently to different people x Everyday observation are often incomplete o They simply can’t provide a lot of information we might want MEASUREMENT x To measure we must do 2 things o Define the property we want to measure o Find a way to Detect it x Operational definition: a description of a property in measurable terms o For example, we can define happiness as “a person’s self-assessment” or “the amount of dopamine in a person’s brain” x Once we have this definition, we need to find a detector: o Some sort of instrument or device that can detect the property we defined For example, a rating scale (to detect a person’s self-assessment), A carbon electrode (to detect dopamine in the brain) x What makes a good operational definition? o Construct Validity: the extent to which a video camera aimed at a face adequately characterizes the property. how well a test or tool measures the construct that it was designed to measure Construct validity is in the eye of the beholder, an operational definition is said to have construct validity when most beholders agree that it adequately characterizes a property x What makes a good detector? o 2 features of a good detector 1. Power: a detector’s ability to detect the presence of difference or changes in the magnitude of a property 2. Reliability: a detector’s ability to detect the absence of differences or changes in the magnitude of a property o A good detector detects differences or changes in the magnitude of a property when they do exist (power), but not when they don’t (reliability) o A detector (or instrument) is reliable when it accurately identifies that there are NO changes in what you are measuring x Demand characteristics: those aspects of an observational setting that cause people to behave as they think someone else wants or expects o How can we avoid demand characteristics? By observing people without their knowledge= Naturalistic observation a technique for gathering scientific information by unobtrusively observing people in their natural environment But not always practical Some events don’t occur naturally Some events can only be observed through direct interaction Privacy and Control People are less likely to be influenced by demand characteristics when they can’t be identified by their actions Measure behaviours that people are unable or unlikely to control Ex. Measuring pupil dilation as you page through a celebrity magazine Unawareness To make sure the people that are being observed are unaware of the true purpose of the study/observation PSYC102[Week 1] xObserver Bias: the tendency for observers’ expectations to influence both what they believe they observed and what they actually observed o Expectations can influence observations o Expectations can influence reality o How do we avoid this? Double-blind study: a study in which neither the researcher nor the participant knows how the participants are expected to behave if research assistants don’t have expectations, then their expectations cannot influence either their observations or their participants’ behaviour. This is why psychologists make sure that the observations in a study are as “blind” to the hypothesis as are the people who are being observed HOW DO WE MEASURE? x Psychologists rarely measure population (a complete collection of people) x They tend to measure the properties of a sample (a partial collection of people or animals or things drawn from a population) x Psychologists have 2 techniques for making sense of big spreadsheets with # 1. Graphic representations 2. Descriptive statistics x Graphic representations: Picturing the data o Most common= Frequency distribution: a graphic representation showing the number of times in which the measurement of a property takes on each of its possible values. Provides a full and complete picture of that sample The general shape of the 2 distributions (on the right) are roughly the same The distribution shown in purple is called the normal distribution: a mathematically defined distribution in which the frequency of measurements is highest in the middle and decreases symmetrically Residents rated their happiness on a 10-point scale in both directions, AKA. Bell curve, Gaussian Distribution x Descriptive Statistics: Summarizing the Data o Descriptive statistics: brief summary statements that capture the essential information from a frequency distribution. o 2 most common kinds are those that: Describe the Central Tendency of a frequency distribution Describe the Variability of a frequency distribution o Descriptions of central tendency are statements about the value of the measurements that tend to lie in the centre or midpoint of the frequency distribution o Descriptions of variability are statements about the extent to which the measurements in a frequency distribution differ from each other, i.e., How wide the distribution is o Central tendency: where is the middle of the distribution 3 most common descriptions of central tendency are: 1. The MODE: the value of the most frequently observed measurements 2. The MEAN: the average value of all the measurements 3. The MEDIAN: the value that is in the middle, i.e., ≥ to half the measurements and ≤ to half the measurements. PSYC102[Week 1] o Variability: How wide is the distribution The simplest measure of variability is the Range: the value of the largest measurement in a frequency distribution minus the value of the smallest measurement When the range is small the distribution has LESS variability than when the range is large A more trickier measure to compute is the Standard deviation: a statistic that describes how each of the measurements in a frequency distribution differs from the mean. i.e., it is an estimate of how far, on average, the various measurements are from the centre of the distribution o Variability and central tendency are independent features of a frequency distribution 1.3 Methods of Explanation: Figuring out Why People do What they do CORRELATION x Synchronized Patterns of Variation o 3 important things were done Measuring a pair of Variables: are properties that can take on different values Made a series of measurements (across a sample of people) rather than just one Looked at the measurements made and tried to identify a pattern o Correlation: occurs when Variations in the value of one variable are synchronized with the variations in the value of the other. When patterns of variation are synchronized two variables are said to be “co-related” Allows us to make educated guesses about measurements without having to measure These predictions are not always accurate o Natural correlation: the correlations we observe in the world around us x Measuring the Direction and Strength of a Correlation o By measuring the direction and strength of the correlation on which the prediction is based we can estimate how accurate the predictions are likely to be o Direction of correlation is either a) positive or b) negative Positive correlation: exists when 2 variables have a “more-is-more” relationship Ex. More health is associated with more wealth, is a positive correlation Negative correlation: exists when 2 variables have a “more-is-less” relationship Ex. More health is associated with less poverty o Correlation coefficient: a mathematical measure of both direction and strength of a correlation (symbolized by the letter r ), r has unlimited range Sign of r (plus/minus) tells you the direction of the relationship (positive or negative) Perfect Positive correlation: the 2 variables being compared have a perfect positive relationship, when one variable moves higher or lower, the other variables moves in the same direction w/ the same magnitude. ( r = 1) Perfect Negative correlation: if one variable increases, the other variable decreases with the same magnitude. ( r = -1) No correlation: if one variable increases, the other variable neither increases nor decreases systematically. ( r = 0 ) PSYC102[Week 1] CAUSATION x The third-variable Problem: Correlation is Not Causation o The third-variable problem: refers to the fact that the natural correlation b/w two variables cannot be taken as evidence of a causal relationship b/w them b/c a third variable might be causing BOTH. I.e., If we want to know about the casual relationship b/w two variables, then observing a natural correlation b/w them can never tell us what we want to know. x Experimentation: Establishing Causation o Experimentation: a technique for establishing the causal relationship b/w variables. The logic: There are 3 possible causes of any correlation, so if we can eliminate two of them, the one that remains must be the real one. How do eliminate 2/3 possible causes? They do this using a pair of technique called manipulation and random assignment. x Manipulation: Making Different Conditions. o Manipulation: a technique for determining the causal power of a variable by actively changing its value Because we manipulated one variable rather than measuring it, we could instantly eliminate two of the possible causes of correlation o We do the Experimentation technique by taking 3 steps 1. Manipulate a variable: The manipulated variable is called the independent variable, it is “independent of” the participants A manipulation creates at least two conditions 2. Measure a variable: The measured variable in an experiment is called the dependent variable, b/c its value “depends on” the participants 3. Compare: compare values of the variable in one condition with the value of the variable in the other. If the variables differ on average, then we know that changes to the value of the independent variable caused changes to the value of the dependent variable. x Random Assignment: Making Sure Conditions Differ in Just ONE way o Self-selection: a problem that occurs when anything abt a participant determines the participant’s condition o Random-assignment: a procedure that assigns participants to a condition by chance (its randomly assigned) x Statistical Testing: Making sure conditions don’t differ by chance o Random assignments don’t always work every time, since it is achieved by a randomizing device ex. A coin o What we can do is calculate the odds that random assignment has failed each time we conducted an experi. Drawing Conclusion x Internal validity: refers to the degree of confidence that the causal relationship being tested is trustworthy and not influenced by other factors or variables. o When an experiment is internally valid, it means that everything inside the experiment is working exactly as it should A change in the Independent variable is the ONLY thing that causes a change in the Dependent variable. x The Representativeness Restriction: “As we Defined that Variable…” o External validity: refers to the extent to which results from a study can be applied (generalized) to other situations, groups or events Can you apply the findings of your study to a broader context? o Experiments are not usually meant to be a representative of everyday life, and as such, external invalidity is usually not a problem PSYC102[Week 1] x The Generalizability Restriction: “In the People we studied..” o The size of a population is signified by the uppercase letter N, and the size of the sample is signified by the letter n o Case Study: a procedure for gathering scientific information by studying a single individual o Random sampling: a technique for selecting participants that ensures that every member of a population has an equal chance for being included in the sample When we randomly sample participants for a population the sample is said to be representative of the population This allows us to generalize from a sample to the population o Non-random sampling Sometimes the representativeness of a sample doesn’t matter Sometimes the representativeness of a sample is a reasonable starting assumptions x The Reliability Restriction: “it is Likely that…” o A Replication: is an experiment that uses the same procedures as a previous experiment but with a new sample from the same population. o 1.5 The Ethics of Science: Doing What’s Right x All research involving human persons or tissue is covered by the Tri-Council Policy Statement (TCPS): o Ethical Conduct for Research Involving Humans. x The “tri-council” refers to the three federal research funding agencies: o the Canadian Institutes of Health Research (CIHR), covers health-related research o the National Sciences and Engineering Research Council (NSERC), covers basic science research o the Social Sciences and Humanities Research Council (SSHRC), social science-related research x Research should show: o Respect for persons: their right to make decisions for and about themselves without undue influence or coercion o Concern for welfare: that it should attempt to maximize benefits and reduce risks to the participant o Be just: that it should distribute benefits and risks equally to participants without prejudice towards particular individuals or groups. x Respecting People o important rules that govern the conduct of psychological research: Informed consent: a verbal agreement to participate in a study made by an adult who has been informed of all the risks that participation may entail Research ethics boards ensure that the rights of human beings who participate in scientific research are based on the principles of respect for persons, concern for welfare, and justice. Psychologists are obligated to uphold these principles by getting informed consent from participants, not coercing their participation, protecting participants from harm, weighing benefits against risks, avoiding deception, and keeping information confidential. Psychologists are obligated to respect the rights of animals and to treat them humanely. Most people are in favour of using animals in scientific research. Psychologists are obligated to tell the truth about their studies, to share credit appropriately, and to grant others access to their data. Freedom from coercion: Psychologists may not coerce participation. Coercion not only means physical and psychological coercion but monetary coercion as well PSYC102[Week 1] Protection from harm: Psychologists must take every possible precaution to protect their research participants from physical or psychological harm. If there are two equally effective ways to study something, the psychologist must use the safer method. If no safe method is available, the psychologist may not perform the study. Risk–benefit analysis: Although participants may be asked to accept small risks, such as a minor shock or a small embarrassment, they may not even be asked to accept large risks, such as severe pain, psychological trauma, or any risk that is greater than the risks they would ordinarily take in their everyday lives Deception: Psychologists may use deception only when it is justified by the study’s scientific, educational, or applied value and when alternative procedures are not feasible Debriefing: If a participant is deceived in any way before or during a study, the psychologist must provide a debriefing, which is a verbal description of the true nature and purpose of a study Confidentiality: Psychologists are obligated to keep private and personal information obtained during a study confidential. o A psychologist may conduct a study only after the REB has reviewed and approved it The REB is a RESEARCH ETHICS BOARD x Respecting animals: o The Canadian Council on Animal Care (CCAC) is the national organization responsible for establishing standards for the ethical use and care of animals in research. Replacement means that researchers have to prove there is no alternative to using animals in research and that the use of animals is justified by the scientific or clinical value of the study. Reduction means that researchers must use the smallest number of animals possible to achieve the research. Refinement means that procedures must be modified to minimize the discomfort, infection, illness, and pain of animals. x Psychology works on a honour system: o No authority is charged with monitoring what psychologists do with the data they’ve collected, and no authority is charged with checking to see if the claims they make are true. What exactly are psychologists on their honour to do? 1. when writing reports of their studies and publishing them in scientific journals, psychologists are obligated to report truthfully on what they did and what they found 2. psychologists are obligated to share credit fairly by including as co-authors of their reports the other people who contributed to the work, as well as by mentioning in their reports the other scientists who have done related work 3. psychologists are obligated to share their data o The fact that anyone can check up on anyone else is part of why the honour system works as well as it does. Reliability and Validity of a Measurement Reading Reliability: refers to the consistency of a measure. Test-retest reliability: When researchers measure a construct that they assume to be consistent across time, then the scores they obtain should be consistent across time. Test-retest reliability is the extent to which this is actually the case Give a person the same test under the same conditions and the person should score consistently on the measure (ex. IQ test score) Test-retest correlation: the consistency of a measure on the same group of people at diﬀerent times Internal consistency/ reliability : the consistency of people’s responses across the items on a multiple item measure ex. On the Rosenberg Self Esteem Scale, people who agree that they are a person of worth should tend to agree that they have a number of good qualities Internal consistency can only be assessed by collecting and analysing data split half correction which is a method of measuring internal consistency through splitting items into two sets and examining the relationship between them A split half correlation of +.80 or greater is generally considered good internal consistency (measured with r) Interrater Reliability: is the extent to which diﬀerent observers are consistent in their judgments If 2 researchers rate a person on the same measure, their scores should be similar Score shouldn’t depend on who is doing the rating ex. Behavioural observation (deﬁning happiness by smiles/ hr) raters should come up with the same number of smiles Validity: refers to the extent to which the scores from a measure represent the variable they are intended to A measure can be extremely reliable but have no validity whatsoever Face Validity: the extent to which a measurement method appears “on its face” to measure the construct of interest Does the test measure what its intended to? Face validity is a weak kind of evidence that a measurement method is measuring what it is suppose to because it is based on people’s intuitions about human behaviour which are frequently wrong Face valid: self report measure of aggressing have questions related to aggression Not face valid: Finger length method of measuring self esteem Many established measures in psychology work quite well despite lacking face validity Content Validity: the extent to which a measure “covers” the construct of interest ex. Psych 101 exam does not under or over represent material and its questions reﬂect what was taught ex. If a researcher conceptually deﬁnes test anxiety as involving both sympathetic nervous system activation (nervous feelings) and negative thoughts, then his measure of test anxiety should include items about both nervous feelings and negative thoughts Criterion Validity: the extent to which people’s scores on a measure are correlated with other variables (known as criteria) that one would expect them to be correlated with ex. People’s scores on a new measure of test anxiety should be negatively correlated with their performance on an important school exam Concurrent validity: when the criterion is measured at the same time as the construct Ex. Social anxiety scale predicts scores on other measure of social anxiety/ phobia Focuses on the ability of the test Predictive validity: when the criterion is measure at some point in the future (after the construct has been measured ex. Social anxiety scale predicts number of social events attended in a week Higher social anxiety= lower amount of events attended Convergent validity: when new measures positively correlate with existing measures of the same constructs ex. Happiness—- Satisfaction, contentment, cheerfulness Discriminant / divergent validity: the extent to which scores on a measure are not correlated with measures of variables that are conceptually distinct ex. People’s self esteem scores should not be very highly correlated with their moods ex. Happiness —- sadness, depression High happy score should not have a high sad score 1 PSYC 101 [WEEK 4] CH 3 NEUROSCIENCE & BEHAVIOUR 3.1 Neurons: the origin of behaviour Al l of ou r thoug hts, feel i ngs, and behaviou rs spri ng from cel ls i n the brai n that take i n i nformation and produce some ki nd of output tri l l ions of ti mes a day. - These cel ls are N EU RO NS :cel ls i n the nervous system that commu nicate with each other to perform i nformation-processi ng tasks Components of the Neu ron: - Neu rons are complex structu res composed of 3 basic parts : the cel l body, the dendrite, and the axon CELL BO DY (also cal led the Soma) - Is the largest component of the neu ron that coordi nates the i nformation-processi ng tasks and keeps the cel l al ive. - Fu nctions such as protei n sy nthesis, energy production and metabol ism takes place here - Cel l body contai ns a nucleus, which houses chromosomes that contai n you r DNA, Caption - The cel l body is enclosed by a porous cel l membrane that al lows some molecu les to flow i nto and out of the cel l. - Neu rons have two ty pes of special ized extensions of the cel l membrane that al low them to commu nicate: TH E DEN DRITE - receives i nformation from other neu rons and relays it to the cel l body - The term dendrites comes from the Greek word for “tree”; b/c most neu rons have many dendrites that look l i ke tree branches. TH E AXO N - TH E PART O F A N EU RO N THAT CARRI ES I N FO RMATI O N TO OTH ER N EU RO NS, M USCLES, O R GLAN DS. - Can be very long, even stretchi ng u p to a metre from the base of the spi nal cord down to the big toe - TH E AXO N IS COVERED I N MYELI N SH EATH: AN I NSU LATI NG LAYER O F FATTY MATERIAL The myel i n sheath is composed of GLIAL CELLS: are su pport cel ls fou nd i n the nervous system. - Recent esti mates suggest there are fewer g l ial cel ls i n the brai n than neu rons - The Gl ial Cel ls serve a nu mber of roles : Some g l ial cel ls digest parts of dead neu rons Some provide physical and nutritional su pport for neu rons Some form myel i n that i nsu lates the axon and al lows it to carry i nformation more efficiently - demyel i nati ng diseases: cause the myel i n sheath to deteriorate, slowi ng commu nication from one neu ron to another For ex, mu lti ple sclerosis This slowdown leads to a variety of problems, i ncludi ng loss of feel i ng i n the l i mbs, partial bl i ndness, and difficu lties i n coordi nated movement and cognition - The the dendrites and axons of neu rons do not actual ly touch each other There’s a smal l gap between the axon of one neu ron and the dendrites or cel l body of another. - This gap is part of the SYNAPSE : the ju nction or region between the axon of one neu ron and the dendrites or cel l body of another Neu rons Special ized by fu nctions - There are three major ty pes of neu rons, each performi ng a disti nct fu nction: 1. SENSO RY N EU RO NS: RECEIVE I N FO RMATI O N FRO M TH E EXTERNAL W O RLD AN D CO NVEY TH IS I N FO RMATI O N TO TH E BRAI N VIA TH E SPI NAL CO RD. - They have special ized endi ngs on thei r dendrites that receive signals for l ig ht, sou nd, touch, taste, and smel l 2. MOTO R N EU RO NS: CARRY SIGNALS FRO M TH E SPI NAL CO RD TO TH E M USCLES TO PRO DU CE MOVEMENT - These neu rons often have long axons that reach to muscles at ou r extremities 1 PSYC 101 [WEEK 4] 3. I NTERN EU RO NS : CO N N ECT SENSO RY N EU RO NS, MOTO R N EU RO NS, O R OTH ER I NTERN EU RO NS. - Most of the nervous system is composed of the i nterneu rons. - Some carry i nformation from sensory neu rons i nto the nervous system - Some carry i nformation from the nervous system to motor neu rons - Some perform a variety of i nformation-processi ng fu nctions withi n the nervous system. - I nterneu rons work together i n smal l ci rcu its to perform si mple tasks, such as identify i ng the location of a sensory signal, and much more compl icated ones, such as recognizi ng a fami l iar face. Neu rons Special ized by Location - Neu rons are also somewhat special ized, dependi ng on thei r location - For ex, Pu rki nje CELLS : are a ty pe of i nterneu ron that carries i nformation from the cerebel lu m to the rest of the brai n and the spi nal cord. - These neu rons have dense, elaborate dendrites that resemble bushes. - PYRAMI DAL CELLS : fou nd i n the cerebral cortex, have a triangu lar cel l body and a si ng le, long dendrite among many smal ler dendrites. - BI PO LAR CELLS : a ty pe of sensory neu ron fou nd i n the reti nas of the eye, have a si ng le axon and a si ng le dendrite. 3.2 The Electrochemical Actions of Neurons: Information Processing - Neu rons are electronical ly excitable cel ls and commu nication of i nformation happens i n the form of electrical signals withi n neu rons and chemical signals between them 1. CO N DU CTI O N : TH E MOVEMENT O F AN ELECTRIC SIGNAL W ITH I N N EU RO NS, FRO M TH E DEN DRITES TO TH E CELL BO DY, TH EN TH RO U GH O UT TH E AXO N 2. TRANSMISSI O N : TH E MOVEMENT O F A SIGNAL FRO M O N E N EU RO N TO AN OTH ER AS A RESU LT O F CH EMICAL SIGNALLI NG ACROSS TH E SYNAPSE. - Together, these stages are what scientists general ly refer to as the ELECTROCH EMICAL ACTI O N of neu rons. Electric Signal l i ng: Conducti ng I nformation Withi n a Neu ron - The neu ron’s cel l membrane has smal l pores that act as channels to al low smal l electrical ly charged molecu les, cal led I O NS, to flow i n and out of the cel l. - It is this flow of ions across the neu ron’s cel l membrane that creates the conduction of an electric signal withi n the neu ron - N EU RO NS HAVE A NATU RAL ELECTRIC CHARGE CALLED TH E RESTI NG POTENTIAL : TH E DI FFERENCE I N ELECTRIC CHARGE BETW EEN TH E I NSI DE AN D O UTSI DE O F A N EU RO N’S CELL MEM BRAN E; A NATU RAL ELECTRIC CHARGE I n the 1930s, the resti ng potential was measu red at about −70 mi l l ivolts I O NS can carry a positive (+) or a negative (−) charge - I n the resti ng state, there is a hig h concentration of positively charged potassiu m ions (K+), as wel l as larger, negatively charged protei n ions (A−), i nside the neu ron’s cel l membrane compared to outside it And there is a hig h concentration of positively charged sodiu m ions (Na+) and negatively charged chloride ions (Cl−) outside the neu ron’s cel l membrane. - Du ri ng the resti ng potential, the i nside of the cel l membrane is negatively charged at −70 mi l l ivolts relative to the outside b/c the A− ions are larger and carry a much stronger charge than the other ion - Normal ly, ions from the area of hig her concentration move to the area of lower concentration u nti l the concentrations are equal but Special channels i n the cel l membrane restrict the movement of the ions i n and out of the cel l. An active chemical “pu mp” i n the cel l membrane hel ps mai ntai n the hig h concentration of K+ ions i nside by pushi ng Na+ ions out of the cel l and pu l l i ng K+ ions i nto the cel l. - This pu mp and other structu res i n the cel l membrane ensu re that du ri ng the resti ng potential, excess K+ ions are bu i lt u p i nside the cel l, ready to rush out to create equ i l i briu m with the low concentration of K+ ions outside the cel l - W hi le excess Na+ ions outside the cel l are ready to rush i n to create equ i l i briu m with the low concentration of Na+ ions withi n the cel l. 2 PSYC 101 [WEEK 4] Channels specific to K+ and Na+ ions i n the membrane are voltage-gated, so they open or close i n response to changes i n the voltage across the membrane. - Du ri ng the resti ng potential, these channels are closed, which al lows the electrical charge i nside the neu ron to bu i ld u p to −70 mi l l ivolts relative to the outside these channels i n the cel l membrane hold back the ions, bu i ldi ng potential energy that can be released i n a fraction of a second ACTI O N POTENTIAL : AN ELECTRIC SIGNAL THAT IS CO N DU CTED ALO NG TH E LENGTH O F A N EU RO N’S AXO N TO A SYNAPSE - Only occu rs when the electric shock reached a certai n level, or threshold W hen the shock was below this threshold, only ti ny signals that dissi pated rapid ly, leavi ng the rest of the axon u naffected W hen the shock reached the threshold, the action potential fi red down the axon. H O W EVER i ncreases i n the electric shock above the threshold did not i ncrease the strength of the action potential. - the action potential is ALL O R N O N E: Electric sti mu lation below the threshold fai ls to produce an action potential, whereas electric sti mu lation at or above the threshold always produces the action potential and always at the same magnitude. - The action potential occu rs due to changes i n the axon’s membrane channels. when the voltage across the cel l body membrane reaches the threshold value, the sodiu m-specific channels on the nearby axon open u p l i ke the floodgate of a dam, and the Na+ ions rush i nto the cel l i nstantaneously The su rge to +40 mi l l ivolts is the di rect resu lt of the Na+ ions floodi ng i nto the cel l, changi ng the total charge i nside the axon from negative to positive i n less than one mi l l isecond - At this poi nt, two events restore the negative charge of the resti ng potential. 1. the Na+ channels i nactivate themselves for several mi l l iseconds, stoppi ng the flow of Na+ ions. Du ri ng this i nactivation ti me, the section of the axon is said to be i n a REFRACTO RY PERI O D: the ti me fol lowi ng an action potential du ri ng which a new action potential cannot be i nitiated. The refractory period l i mits the nu mber of ti mes per second a neu ron can fi re and keeps the action potential from travel l i ng back towards the cel l body. 2. Channels specific to the K+ ions open, al lowi ng the excess K+ ions i nside the cel l to escape. The rapid exit of the positively charged K+ ions retu rns the electrical charge of the membrane to a negative state, after which the K+ channels close. Ion pu mps conti nue to push Na+ ions out of the cel l and bri ng i n additional K+ ions. Along with other special channels, they retu rn the concentrations of ions to the resti ng potential - How does the action potential move down the axon? IT’S A DO MI N O EFFECT Once the fi rst voltage-gated channels open and Na+ ions rush i nto the cel l, the ions spread and i ncrease the electrical charge down the i nside of the axon. W hen the voltage arou nd adjacent voltage-gated channels reaches the threshold, those channels open and let i n more Na+ ions that spread even farther. - the i nflux of Na+ ions triggers nearby channels to open, and the process repeats down the enti re axon - Each releases the same amou nt of energy, & each open channel lets i n just enoug h Na+ ions to cause a spi ke to +40 mi l l ivolts. - The conduction of the action potential is greatly i ncreased by the presence of a myel i n sheath arou nd the axon. The MYELI N SH EATH clu mps arou nd the axon with l ittle break poi nts between clu mps - These breakpoi nts are cal led the N O DES O F RANVI ER, after the French pathologist Lou is-Antoi ne Ranvier, who discovered them - SALTATO RY CO N DU CTI O N : CU RRENT SEEMS TO “JU M P” Q U ICKLY FRO M N O DE TO N O DE W H ERE IT SLO WS DO W N it hel ps speed the flow of i nformation down the axon Chemical Signal l i ng: Transmission Between Neu rons - Axons usual ly end i n TERMI NAL BUTTO NS: knobl i ke structu res at the end of an axon Each termi nal button is fi l led with ti ny vesicles or bags that contai n N EU ROTRANSMITTERS: chemicals that transmit i nformation across the sy napse to a receivi ng neu ron’s dendrites The dendrites of the receivi ng neu ron contai n RECEPTO RS: parts of the cel l membrane that receive neu rotransmitters and either i nitiate or prevent a new electric signal. - TH E PROCESS The presy naptic neu ron ( sendi ng neu ron) travels down the length of the axon to the termi nal buttons, where it sti mu lates the release of neu rotransmitters from vesicles i nto the sy napses. 3 PSYC 101 [WEEK 4] The neu rotransmitters qu ickly float across the sy napse and bi nd to receptor sites on the nearby dendrite of the receivi ng neu ron, or postsy naptic neu ron - TH E SYNAPTIC TRANSMISSI O N :The sendi ng and receivi ng of chemical neu rotransmitters u lti mately u nderl ies ou r thoug hts, emotions, and behaviou r. W hen the postsy naptic neu ron receives a neu rotransmitter, it may activate nearby ion channels, which can either raise or lower the voltage across the membrane. Dependi ng on the combi nation and ti mi ng of the neu rotransmitters acti ng on the neu ron, the voltage i nside the cel l body membrane may reach the threshold and trigger a new action potential Then the neu rotransmitters’ chemical messages create an electrical signal, and the electrochemical process of neu ronal commu nication conti nues - W hat tel ls the dendrites which of the neu rotransmitters floodi ng i nto the sy napse to receive? 1. neu rons tend to form pathways i n the brai n that are characterized by specific ty pes of neu rotransmitters one neu rotransmitter mig ht be prevalent i n one part of the brai n, whereas a different neu rotransmitter mig ht be prevalent i n a different part of the brai n. 2. neu rotransmitters and receptor sites act l i ke a lock-and-key system only some neu rotransmitters bi nd to specific receptor sites on a dendrite - Neu rotransmitters leave the sy napse throug h three processes 1. REU PTAKE: occu rs when neu rotransmitters are absorbed by the termi nal buttons of the presy naptic neu ron’s axon or by neig hbou ri ng g l ial cel ls 2. ENZYME DEACTIVATI O N: A process where , neu rotransmitters can be destroyed by enzy mes i n the sy napse - specific enzy mes break down specific neu rotransmitters 3. DI FFUSI O N : occu rs when neu rotransmitters drift out of the sy napse and can no longer reach receptors - Neu rotransmitters can also bi nd to receptor sites on the presy naptic neu ron cal led autoreceptors. - Autoreceptors detect how much of a neu rotransmitter has been released i nto a sy napse and may stop the release of more. Ty pes and Fu nctions of Neu rotransmitters 1. ACETYLCH O LI N E (ACh) : a neu rotransmitter i nvolved i n a nu mber of fu nctions, i ncludi ng volu ntary motor control - fou nd i n neu rons of the brai n and i n the sy napses where axons connect to muscles and body organs, such as the heart - activates muscle movements, and it also contri butes to the regu lation of attention, learni ng, sleepi ng, dreami ng, and memory - For ex, Alzhei mer’s disease, a medical condition i nvolvi ng severe memory i mpai rments, is associated with the deterioration of ACh- produci ng neu rons. 2. DO M PAMI N E: a neu rotransmitter that regu lates motor behaviou r, motivation, pleasu re, and emotional arousal. - H ig h levels of dopami ne i n some brai n pathways are l i nked to schizophrenia - low levels i n other areas are l i nked to Parki nson’s disease. - This drug L-dopa is used to treat Parki nson’s disease 3. GLUTAMATE: the major excitatory neu rotransmitter i n the brai n, - it enhances the transmission of i nformation between neu rons - GABA (gamma-ami nobuty ric acid): the pri mary i nhi bitory neu rotransmitter i n the brai n - tends to prevent the fi ri ng of neu rons. - Too much g lutamate, or too l ittle GABA, can cause neu rons to become overactive, causi ng seizu res 4. Two related neu rotransmitters i nfluence mood and arousal: norepi nephri ne and serotoni n 1. N O REPI N EPH RI N E : i nvolved i n states of vigi lance, or a heig htened awareness of dangers i n the envi ronment 2. SEROTO N I N : i nvolved i n the regu lation of sleep and wakefu l ness, eati ng, and aggressive behaviou r 4 PSYC 101 [WEEK 4] - low levels of each have been i mpl icated i n mood disorders 5. EN DO RPH I N ES ; chemicals that act withi n the pai n pathways and emotion centres of the brai n Morphi ne is a drug that has an i ntensely pleasu rable and pai n-rel ievi ng effect - An endorphi n is an i nternal ly produced su bstance that has si mi lar but less i ntense properties - For ex, “ru nner’s hig h” experienced by many athletes as they push thei r bodies to pai nfu l l i mits of endu rance can be explai ned by the release of endorphi ns i n the brai n How Drugs Mi mic Neu rotransmitters - AGO N ISTS : drugs that i ncrease the action of a neu rotransmitter - ANTAGO N ISTS : drugs that di mi nish the fu nction of a neu rotransmitter. - Some drugs alter a step i n the production or release of the neu rotransmitter, - whereas others have a chemical structu re so si mi lar to a neu rotransmitter that the drug is able to bi nd to that neu ron’s receptor - Parki nson’s disease is caused by the loss of neu rons that make the neu rotransmitter dopami ne by modify i ng L-dopa produced natu ral ly i n the body The L-dopa drug acts as an agonist for dopami ne by i ncreasi ng its production - However the drugs’ effectiveness ty pical ly decreases when used over a long period of ti me STREET DRU GS Amphetami ne and Cocai ne are agonists, 1. AM PH ETAMI N E : sti mu lates the release of norepi nephri ne and dopami ne and also blocks thei r reu ptake. This combi nation creates an excess of neu rotransmitters that flood the sy napse, activati ng thei r receptors over and over 2. COCAI N E : acts by preventi ng the reu ptake of neu rotransmitters - Norepi nephri ne and dopami ne play a critical role i n mood control, such that an i ncrease i n either neu rotransmitter resu lts i n eu phoria, wakefu l ness, and a bu rst of energy. it also i ncreases heart rate, - OVERDOSE: of amphetami ne or cocai ne can cause the heart to contract so rapid ly that heartbeats do not last long enoug h to pu mp blood effectively, leadi ng to fai nti ng and someti mes death 3. O PI O DS are a class of chemical ly si mi lar drugs either derived : natu ral ly from the opiu m poppy (such as morphi ne and heroi n) made sy nthetical ly (such as oxycodone, hydrocodone, and fentany l). - Opioids work i n part by acti ng as agonists for endorphi ns, which creates powerfu l feel i ngs of cal m and eu phoria. - Have been widely prescri bed for pai n rel ief because they are also hig hly effective antagonists that decrease the release of neu rotransmitters i nvolved i n the perception of pai n Opioids also di mi nish the brai n stem’s sensitivity to risi ng levels of carbon dioxide i n the blood, which depresses breathi ng OVERDOSE: can lead to asphyxiation and death - Opioid addiction response: is to equ i p fi rst responders with the drug naloxone, the active i ngredient i n the nasal spray Narcan - NALOXO N E is also an opioid but one that acts as an antagonist: It bi nds with opioid receptors, blocki ng agonists l i ke heroi n and preventi ng thei r effects on neu rons 4. PROZAC : an agonist drug commonly used to treat depression - Prozac blocks the reu ptake of the neu rotransmitter serotoni n, - It is part of a category of drugs cal led SELECTIVE SEROTO N I N REU PTAKE I N H I BITO RS, or SSRIs 5 PSYC 101 [WEEK 4] - People sufferi ng from cl i nical depression ty pical ly have reduced levels of serotoni n i n thei r brai ns. By blocki ng reu ptake, more of the neu rotransmitter remai ns i n the sy napse longer and produces greater activation of serotoni n receptors. Serotoni n elevates mood, which can hel p rel ieve depression 5. PRO PRANALO L : one of a class of drugs cal led beta blockers. - An antagonist drug - These drugs obstruct receptor sites i n the heart for norepi nephri ne, a neu rotransmitter that i ncreases one’s heartbeat - Because norepi nephri ne cannot bi nd to these receptors, the heart rate slows down, which is hel pfu l for disorders i n which the heart beats too fast or i rregu larly. - Beta blockers are also prescri bed to reduce the agitation, raci ng heart, and nervousness associated with stage frig ht 3.3 Organization of the Nervous System - Nerves are bu nd les of axons and the g l ial cel ls that su pport them - N ERVO US SYSTEM: an i nteracti ng network of neu rons that conveys electrochemical i nformation throug hout the body DIVISI O N O F TH E N ERVO US SYSTEM - 2 major divisions 1. The Central Nervous System (CNS): composed of the brai n and spi nal cord. - It receives sensory i nformation from the external world, processes and coordi nates this i nformation, and sends commands to the skeletal and muscu lar systems for action. The brai n contai ns structu res that su pport the most complex perceptual, motor, emotional, and cognitive fu nctions of the nervous system The spi nal cord branches down from the brai n; - nerves that process sensory i nformation and relay commands to the body connect to the spi nal cord. 2. The Peri pheral Nervous System (PNS) : connects the central nervous system to the body’s organs and muscles. - Composed of two major su bdivisions: 1. TH E SO MATIC N ERVO US SYSTEM (SNS) : a set of nerves that conveys i nformation between volu ntary muscles and the central nervous system - We have conscious control over this system and use it to perceive, thi nk, and coordi nate thei r behaviou rs. 2. TH E AUTO N O MIC N ERVO US SYSTEM (ANS) : a set of nerves that carries i nvolu ntary and automatic commands that control blood vessels, body organs, and g lands. - It works on its own to regu late bodi ly systems, largely outside of conscious control. - 2 Major su bdivisions : - A) SYM PATH ETIC N ERVO US SYSTEM: a set of nerves that prepares the body for action i n chal lengi ng or threateni ng situations; FIGHT or FLIGHT - B) PARASYM PATH ETIC N ERVO US SYSTEM: hel ps the body retu rn to a normal resti ng state. - General ly mi rrors the connections of the sy mpathetic nervous system - I n men, the parasy mpathetic nervous system engorges the blood vessels of the penis to produce an erection, but the sy mpathetic nervous system is responsi ble for ejacu lation. - I n women, the parasy mpathetic nervous system produces vagi nal lu brication, but the sy mpathetic nervous system u nderl ies orgasm. - I n both men and women, a successfu l sexual experience depends on a del icate balance of these two systems; i n fact, anxiety about sexual performance can disru pt this balance. For i nstance, sy mpathetic nervous system activation caused by anxiety can lead to prematu re ejacu lation i n males and lack of lu brication i n females. Components of the nervous system - Connections between the sensory i nputs and motor neu rons i n the spi nal cord mediate SPI NAL REFLEXES : si mple pathways i n the nervous system that rapid ly generate muscle contractions 6 PSYC 101 [WEEK 4] With a few sy naptic connections withi n the spi nal cord, i nterneu rons relay these sensory i nputs to motor neu rons that connect to you r arm muscles and di rect you to qu ickly retract you r hand. REFLEX ARC : neu ral pathway that controls reflex actions - Can i nclude sensory neu rons, i nterneu rons, and motor neu rons - some si mple reflex arcs are comprised of only sensory and motor neu rons. The peri pheral nervous system sends messages from sensory neu rons throug h the spi nal cord i nto the brai n The brai n sends commands for volu ntary movement throug h the spi nal cord to motor neu rons, whose axons project out to skeletal muscles Damage to the spi nal cord severs the connection from the brai n to the sensory and motor neu rons that are essential to sensory perception and movement The location of the spi nal i nju ry often determi nes the extent of the abi l ities lost because different regions of the spi nal cord control different systems of the body A spi nal i nju ry hig her u p the cord usual ly predicts a much poorer prognosis, such as quadri plegia (loss of sensation and motor control over al l l i mbs), breathi ng throug h a respi rator and l ifelong i mmobi l ity 3,4 Structure of the brain The H i nd brai n: - H I N D BRAI N: an area of the brai n that coordi nates i nformation comi ng i nto and out of the spi nal cord Looks l i ke a stal k on which the rest of the brai n sits and controls. the most basic fu nctions of l ife: respi rator, alertness and motor ski l ls Structu res that make u p the hi nd brai n i nclude, the medu l la, the reticu lar formation, the cerebel lu m and the pons Medu l la: an extension of the spi nal cord i nto the sku l l that coordi nates heart rate, ci rcu lation, and respi ration Reticu lar formation: cluster of neu rons that begi ns i nside the medu l la and extends u pward. Regu lates sleep, wakefu l ness and levels of arousal Cerebel lu m: a large structu re of the hi nd brai n that controls fi ne motor ski l ls Orchestrates the proper sequence of movements when we ride a bi ke, play the piano or mai ntai n balance whi le wal ki ng and ru nni ng Contri butes to the fi ne tu ni ng of behaviou r, smoothi ng ou r actions to al low thei r gracefu l execution rather than i nitiati ng the actions Pons: a structu re that relays i nformation from the cerebel lu m to the rest of the brai n Essential ly acts as a relay station or bridge between the cerebel lu m and other structu res of the brai n The Mid brai n: - Connects two mai n structu res: the tectu m and the tegmentu m - Tectu m: orients an organism i n the envi ronment Receives sti mu lus i nput from the eyes, ears and ski n and moves the organism i n a coordi nated way towards the sti mu lation - Tegmentu m: i nvolved i n movement and arousal; it also hel ps to orient an organism towards sensory sti mu l i - The mid brai n may be relatively smal l but it is the central location of neu rotransmitters i nvolved i n arousal, mood and motivation and brai n structu res that rely on them - You cou ld su rvive if you only had a hi nd brai n and a mid brai n The structu res i n the hi nd brai n wou ld take care of al l the bodi ly fu nctions necessary to sustai n l ife and the structu res i n the mid brai n wou ld orient you towards or any from pleasu rable or threateni ng sti mu l i i n the envi ronment The Forebrai n - The forebrai n is the hig hest level of the brain (l iteral ly and figu ratively) and controls complex cognitive, emotional, sensory and motor fu nctions Cerebral cortex: the outermost layer of the brai n, visi ble to the naked eye, and divided i nto two hemispheres Su bcortical structu res: areas of the forebrai n housed u nder the cerebral cortex near the centre of the brai n Su bcortical Structu res: Thalamus and Hy pothalamus: located i n the centre of the brai n, i nteract closely with several other brai n structu res Thalamus: relays and fi lters i nformation from the senses and transmits the i nformation to the cerebral cortex Receives i nputs from al l the major senses except smel l which has di rect connections to the cerebral cortex Thalamus acts as a ki nd of computer server i n a networked system, taki ng i n mu lti ple i nputs and relay i ng them to a variety of locations Thalamus actively fi lters sensory i nformation, givi ng more worth to some i nputs and less weig ht to others. Thalamus also closes the pathways of i ncomi ng sensations du ri ng sleep, providi ng a valuable fu nction i n not al lowi ng i nformation to pass to the rest of the brai n 7 PSYC 101 [WEEK 4] Hy pothalamus: located below the thalamus, regu lates body temperatu re, hu nger, thi rst and sexual behaviou r Neu rons i n the hy pothalamus oversee a wide range of of basic behaviou rs, keepi ng body temperatu re, blood sugar levels and metabol ism withi n an opti mal range for normal hu man fu nctioni ng Lesions to some areas of the hy pothalamus resu lt i n overeati ng, whereas lesions i n other areas leave an ani mal with no desi re for food at al l W hen you thi nk about sex, messages from you r cerebral cortex are sent to the hy pothalamus to trigger the release of hormones - The Li mbic System: A grou p of the forebrai n structu res that i ncludes the hy pothalamus, the hi ppocampus and the amygdala which are i nvolved i n motivation, emotion, learni ng and memory Li mbic system is where the su bcortical structu res meet the cerebral cortex H i ppocampus: is critical for creati ng new memories and i ntegrati ng them i nto a network of knowledge so that they can be stored i ndefi nitely i n other parts of the cerebral cortex - I ndividuals with damage to the hi ppocampus can acqu i re new i nformation and keep it i n awareness for a few seconds, but as soon as they are distracted, they forget the i nformation and the experience that produced it - Memory of learned habitual routi nes or emotional reactions remai ns i ntact ex. People with damage to the hi ppocampus can remember how to drive and tal k, but can’t recal l where they have recently driven or a conversation they just had Amygdala: located at the ti p of each horn of the hi ppocampus, plays a central role i n many emotional processes, particu larly the formation of emotional memories - The amygdala attaches significance to previously neutral events that are associated with fear, pu nishment, or reward - W hen we are i n emotional ly arousi ng situations, the amygdala sti mu lates the hi ppocampus to remember many detai ls su rrou ndi ng the situation The Basal Gang l ia: - Basal gang l ia: is not one structu re but a set of su bcortical structu res that di rects i ntentional movements - Located near the thalamus and hy pothalamus, the basal gang l ia receive i nput from the cerebral cortex and send outputs to the motor centres i n the brai n stem - One part of the basal gang l ia, the striatu m, has an i mportant role i n the control of postu re and movement - People with Parki nson’s disease ty pical ly show sy mptoms of u ncontrol lable shaki ng and sudden jerks of the l i mbs and are u nable to i nitiate a sequence of movements to achieve a specific goal. This happens because Parki nson’s disease damages parts of the mid brai n that normal ly su pply the striatu m with dopami ne The u ndersu pply of dopami ne i mpai rs the fu nction of the striatu m, which i n tu rn leads to the visi ble tremors of Parki nson’s This disease i l lustrates 2 themes of the brai n and behaviou r: - Actions at the microscopic level of neu rons i n the brai n can produce su bstantial effects at the level of observable behaviou r - The structu res i n the hi nd brai n, mid brai n and forebrai n don’t fu nction i n isolation, they are i nterdependent and damage i n one area affects other areas i n tu rn The Endocri ne System: - Endocri ne System: is a network of g lands that produce and secrete i nto the bloodstream chemical messages known as hormones, which i nfluence a wide variety of basic fu nctions, i ncludi ng metabol ism, growth and sexual development The endocri ne system is disti nct from the nervous system but works closely with it, especial ly the l i mbic system, to regu late thoug hts, emotions, and behaviou rs. - Some of the mai n g lands i n the endocri ne system i nclude the: - thy roid, which regu lates bodi ly fu nctions such as body temperatu re and heart rate, - the adrenals, which regu late stress responses, - the pancreas, which controls digestion - pi neal, which secretes melatoni n, i nfluenci ng the sleep/wake cycle - Pitu itary g land: the “master g land” of the body’s hormone produci ng system, which releases hormones that di rect the fu nctions of many other g lands i n the body - The overal l fu nctioni ng of the endocri ne system is orchestrated by the pitu itary g land - The hy pothalamus sends hormonal signals to the pitu itary g land, which i n tu rn sends hormonal signals to other g lands to control stress, digestive activities, and reproductive processes - The endocri ne system also plays a key role i n sexual behaviou r and reproductions - The sexual reproductive g lands are the ovaries i n females, which make the hormone estrogen, and the tests i n males, which make the hormone testosterone. However, testosterone is not exclusive to males, and estrogen is not exclusive to females: the ovaries generate smal l amou nts of testosterone and the testes generate smal l amou nts of estrogen The cerebral cortex: 8 PSYC 101 [WEEK 4] - The cortex is the hig hest level of the brai n, and is responsi ble fro the most complex aspects of out perception, emotion, movement and thoug ht - It sits over the rest of the brai n l i ke a mushroom cap shieldi ng the u nderside and stem and it is the wri nkled su rface you see when looki ng at the brai n with the naked eye - The smooth su rfaces of the cortex— the raised part are cal led gy ri (gy rus if you are just tal ki ng about one) - The i ndentations or fissu res are cal led su lci (su lcus when si ngu lar) - The fu nctions of the cerebral cortex can be u nderstood at three levels: - The separation of the cortex i nto two hemispheres, - the fu nctions of each hemisphere, - The role of specific cortical areas Organization Across Hemispheres: - The fi rst level of organization divides the cortex i nto the left and rig ht hemispheres - Each hemisphere controls the fu nctions of the opposite side of the body - Contralateral control: you r rig ht cerebral hemisphere perceives sti mu l i from and controls movements on the left side of you r body, whereas you r left cerebral hemisphere perceives sti mu l i from and controls movements on the rig ht side of you r body - The cerebral hemispheres are connected to each other by commissu res, bu nd les of axons that make possi ble commu nication between paral lel areas of the cortex i n each half - Corpus cal losu m: connects large ares of cerebral cortex on each side of the brai n and su pports commu nication of i nformation across the hemispheres This means i nformation received i n the rig ht hemisphere, for example can pass across the corpus cal lous and be registered, vi rtual ly i nstantaneously, i n the left hemisphere Organization withi n the hemispheres - The second level of organization i n the cerebral cortex disti ngu ishes the fu nctions of the different regions withi n each hemisphere of the brai n - Each hemisphere of the cerebral cortex is divided i nto fou r areas, or lobes 1. Occi pital lobe: located at the back of the cerebral cortex, processes visual i nformation 2. Parietal lobe: located i n front of the occi pital love, carries out fu nctions that i nclude processi ng i nformation about touch Contai ns the somatosensory cortex, a stri p of brai n tissues ru nni ng from the top of the brai n down to the sides Each part of the somatosensory cortex maps onto a particu lar part of the body 3. Temporal lobe: located on the lower side of each hemisphere, is responsi ble for heari ng and language The pri mary auditory cortex receives sensory i nformation from the ears based on the frequencies of sou nds Secondary areas of the temporal lobe then process the i nformation i nto meani ngfu l u nits, such as speech or words The temporal lobe also houses areas that i nterpret the meani ng of visual sti mu l i and hel p us recognize common objects i n the envi ronment 4. Frontal lobe: sits behi nd the forehead, has special ized areas for movement, abstract thi nki ng, planni ng, memory, and judgement Contai ns the motor cortex, which coordi nates movements of muscle grou ps throug hout the body Other ares of the frontal lobe coordi nate thoug ht processes that hel p us mani pu late i nformation and retrieve memories, which we can use to plan ou r behaviou rs and i nteract social ly with others The frontal cortex al lows us to do the ki nd of thi nki ng, i magi ni ng, planni ng, and antici pati ng that sets hu mans apart form most other species Organization withi n specific lobes - The thi rd level of organization i n the cerebral cortex i nvolves representation of i nformation withi n specific lobes i n the cortex Association areas: are composed of neu rons that hel p provide sense and meani ng to i nformation registered i n the cortex - ex. Neu rons i n the pri mary visual cortex are hig hly special ized: some detect featu res of the envi ronment that are i n a horizontal orientation, others detect movement, and sti l l others process i nformation about hu man versus nonhu man forms - Association areas i nterpret the i nformation extracted by these pri mary areas (shape, motion, etc.) to make sense of what is bei ng perceived Mi rror neu rons: are active when an ani mal performs a behaviou r, such as reachi ng for or mani pu lati ng an object, and are also activated when another ani mal observes that ani mal performi ng the same behaviou r - Mi rror neu rons are fou nd i n the frontal lobe (near the motor cortex) and i n the parietal lobe - Neu roi magi ng studies with hu mans have shown that mi rror neu rons are active when people watch someone perform a behaviou r, such as graspi ng i n midai r, but are more hig hly activated when the behaviou r has some pu rpose or context, such as graspi ng a cu p to take a dri nk - I mpai rments to the mi rror neu ron system contri bute to difficu lties with u nderstandi ng the mi nds of other people, as occu rs i n autism spectru m disorder - Neu rons i n the association areas are usual ly less special ized and more flexi ble than neu rons i n pri mary areas, which means they can be shaped by learni ng and experience to do thei r job more effectively Brai n plasticity: - Sensory cortices are not fixed and they can adapt to changes i n sensory i nputs, a qual ity that researchers cal led plasticity (the abi l ity to be mou lded) - The brai n is plastic: fu nctions that were assigned to certai n areas of the brai n may be capable of bei ng reassigned to other areas of the brai n to 9 PSYC 101 [WEEK 4] accommodate changi ng i nput from the envi ronment - This suggests that sensory i nputs “compete” for representation i n each cortical area New mappi ng: - amputees who conti nue to experience sensations from where the missi ng l i mb wou ld be, a phenomenon cal led phantom l i mb sy ndrome. - Brai n scans of amputees revealed that sti mu lati ng areas of the face and u pper arm activated an area i n the somatosensory cortex that previously wou ld have been activated by a now missi ng hand Brai n plasticity can explai n these resu lts The somatosensory areas for the face and u pper arm were larger i n amputees and had taken over the part of the cortex normal ly representi ng the hand - ex. I n some amputees when specific areas of the facial ski n were activated, the patient reported sensations i n just one fi nger of the phantom hand The i nfluence of practice: - Plasticity doesn’t occu r only to compensate for missi ng digits or l i mbs - An extraordi nary amou nt of sti mu lation of one fi nger can resu lt i n that fi nger’s “taki ng over” the representation of the part of the cortex that usual ly represents other adjacent fi ngers - It is l i kely that concert pianists have hig hly developed cortical areas for fi nger control: the conti nued i nput from di ners commands a larger areas of representation i n the somatosensory cortices i n the brai n - Consistent with this idea, research i ndicated greater plasticity withi n the motor cortex of professional musicians compared with non-musicians, perhaps reflecti ng an i ncrease i n the nu mber of motor sy napses as a resu lt of extended practice The i nfluence of exercise: - A large nu mber of studies i n rats and other nonhu man ani mals i ndicate that physical exercise can i ncrease the nu mber of sy napses and even promote the development of new neu rons i n the hi ppocampus - Recent studies with people have begu n to docu ment beneficial effects of cardiovascu lar exercise on aspects of brai n fu nction and cognitive performance - Some evidence i ndicated that even a si ng le session of moderate to i ntensive exercise can boost aspects of memory and motor ski l ls The adaptive brai n: u nderstandi ng its evolution - The central nervous system evolved from very basic ones fou nd i n si mple ani mals to elaborate nervous system i n hu mans today - Even the si mplest ani mals have sensory neu rons and motor neu rons for respondi ng to the envi ronment - ex. Si ng le cel led Protozoa have molecu les i n thei r cel l membrane that are sensitive to food i n water A division forms: vertebrates and i nvertebrates - I n al l vertebrates, the central nervous system is organized i nto a hierarchy: the lower levels of the brai n and spi nal cord execute si mpler fu nctions, whi le the hig her levels of the nervous system perform more complex fu nctions - The forebrai n u ndergoes fu rther evolutionary advances i n vertebrates. I n lower vertebrate species such as amphi bians, the forebrai n consists only of smal l clusters of neu rons at the end of the neu ral tu be - I n hig her vertebrates, i ncludi ng repti les, bi rds and mammals, the forebrai n is much larger, and it evolves i n two patterns - Repti les and bi rds have al most no cerebral cortex - Mammals have a hig hly developed cerebral cortex consisti ng of mu lti ple areas that serve a broad range of hig her mental fu nctions 3.5 Genes, Epigenetics, and the Environment W hat are genes: - Gene: is the major u nit of hereditary transmission - Chromosomes: strands of DNA wou nd arou nd each other i n a dou ble hel ix configu ration - The DNA i n ou r chromosomes produces protei n molecu les throug h the action of a molecu le known as messenger RNA which commu nicates a copt of DNA code to cel ls that produce protei ns - Chromosomes come i n pai rs and hu mans 23 pai rs - Females have two X chromosomes - Males have a X and Y chromosome - Chi ldren share half thei r genes with each parent, a quarter of thei r genes with thei r grandparents and an eig hth with cousi ns, and so on - The probabi l ity of shari ng genes is cal led degree of relatedness - Monozygotic twi ns (identical twi ns) are the most genetical ly related people Develop from the spl itti ng of a si ng le ferti l ized egg and therefore share 100% of thei r genes - Dizygotic twi ns (fraternal twi ns) Develop from two separate ferti l ized eggs and share 50% of thei r genes, the same as any two si bl i ngs born separately - Genetics can contri bute to development, l i kel i hood, or onset of a variety of traits but a more complete pictu re of genetic i nfluence on behaviou r must always take the envi ronmental context i nto consideration - Genes express themselves withi n an envi ronment, not i n isolation A role for epigenetics: 10 PSYC 101 [WEEK 4] - Epigenetic: the study of envi ronmental i nfluences that determi ne whether or not genes are expressed, or the degree to which they are expressed, without alteri ng the basic DNA sequences that constitute the genetics themselves - Dependi ng on the envi ronment, a gene can be expressed or not expressed without alteri ng the u nderly i ng DNA code - Epigenetic marks: chemical modifications to DNA can tu rn genes on or off How the envi ronment i nfluences gene expression - 2 widely studied epigenetic marks: - DNA methy lation: i nvolves addi ng a methy l grou p to DNA Althoug h addi ng a methy l grou p doesn’t alter the basic DNA sequence, it switches off the methy lated gene - H istone modification: i nvolves addi ng chemical modifications to protei ns cal led histones that are i nvolved i n packagi ng DNA DNA is tig htly wrapped arou nd grou ps of histone protei ns H istone modification can either switch genes off or tu rn them on The relevance of Epigenetics to the brai n: - Experi ments with rats and mice have shown that epigenetic marks left by DNA methy lation and histone modification play a role i n learni ng and memory - Studies have l i nked epigenetic changes with response to stress, i ncludi ng research with hu mans - ex. Studies of nu rses worki ng i n hig h stress versus low stress envi ronments fou nd differences between the two grou ps i n DNA methy lation Epigenetics and early l ife experiences: - DNA methy lation and histone modifications also play a key role i n the long lasti ng effects of early experiences for both rats and hu mans The hig h l icki ng and groomi ng rat mothers, versus low l icki ng and groomi ng rat mothers - Studies show a role for epigenetic i n the persisti ng effects of chi ld hood abuse i n adu lt men - Related studies suggest that the effects of early experience are not restricted to a si ng le gene, but occu r more broad ly The role of envi ronmental factors: - Heritabi l ity: a measu re of the variabi l ity of behaviou ral traits among i ndividuals that can be accou nted for by genetic factors - Calcu lated as a proportion and its nu merical value (i ndex) ranges from 0 to 1.00 - Heritabi l ity of 0 means that genes don’t contri bute to i ndividual difference i n the behaviou ral trait - Heritabi l ity of 1.00 means that genes are the only reason for the i ndividual differences - Scores of 0 or 1.00 occu r so i nfrequently that they are theoretical l i mits rather than real istic ones. Al most nothi ng i n hu man behaviou r is completely due to envi ronment or owed completely to genetic i nheritance Scores between 0 and 1.00 i ndicate that i ndividual differences are caused by vary i ng degrees of genetic and envi ronmental contri butions For hu man behaviou r, al l esti mates of heritabi l ity are i n the moderate range between 0.30 and 0.60 ex. 0.50 for i ntel l igence i ndicates that half of the variabi l ity i n i ntel l igence test scores is attri butable to genetic i nfluences and the remai ni ng half is due to envi ronmental i nfluences 4 i mportant poi nts about heritabi l ity to bear i n mi nd: 1. Heritabi l ity is an abstract concept: it tel ls us nothi ng about the specific genes that contri bute to a trait 2. Heritabi l ity is a popu lation concept: it tel ls us nothi ng about an i ndividual. Heritabi l ity provides gu idance for u nderstandi ng difference across i ndividuals i n a popu lation rather than abi l ities withi n an i ndividual 3. Heritabi l ity is dependent on the envi ronment. Heritabi l ity is meani ngfu l only for the envi ronmental conditions i n which it was computed, and heritabi l ity estates may change dramatical ly u nder other envi ronmental conditions 4. Heritabi l ity is not fate: it tel ls us nothi ng about the degree to which i ntervention can change a behaviou ral trait. Heritabi l ity is usefu l for identify i ng behaviou ral traits that are i nfluenced by genes, but is not usefu l for determi ni ng how i ndividuals wi l l respond to particu lar envi ronmental conditions or treatments 3.6 investigating the brain Study i ng the damaged brai n: By study i ng behaviou r and cognition i n people with known patterns of brai n damage, neu roscientists can theorise about the fu nctions those brai n areas normal ly perform The emotional fu nctions of the frontal lobes: - The frontal lobe is i nvolved i n emotion regu lation, planni ng, and decision maki ng - Phi neas Gage’s accident of havi ng a pole go throug h his head Because the connections between the frontal lobe and su bcortical structu res of the l i mbic system were affected, scientists were able to better u

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