PSYCH 104 CONT. 2 PDF

Topic 1: Biological Behavior Basis The Nervous System Central Nervous System (CNS) - Composed of brain, spinal cord, optic nerve, and retina Peripheral Nervous System (PNS) - Everything else - Autonomic → involuntary, think: automatic Regulates...

Topic 1: Biological Behavior Basis The Nervous System Central Nervous System (CNS) - Composed of brain, spinal cord, optic nerve, and retina Peripheral Nervous System (PNS) - Everything else - Autonomic → involuntary, think: automatic Regulates emotions along with the limbic system Sympathetic → fight or flight Parasympathetic → rest and digest - Somatic → voluntary Relays information between the CNS and the rest of the body The Brain! (Briefly) - Made up of neurons and glial (neuroglia) cells Neurons rely on oxygen and glucose to live *injuries such as a stroke will starve the brain of oxygen, causing neurons to die* 4 different types of glial cells You have more billions of both neurons and glia, but more neurons Neurons Dendrites - “Tapered extensions” that collect impulses from the axon terminals of another neuron Cell Body/Soma - Cellular molecules are manufactured here - Contains organelles (ie. Nucleus, Ribosome, Mitochondria) - Allow it to translate genetic instructions into proteins for neuron Axon - Nodes of ranvier allow action potentials to regenerate so signal is not lost - Coated in myelin (white matter) which acts as a protective coat that speeds up impulses Multiple sclerosis is a condition in which myelin has deteriorated  Axon Terminals - “Presynaptic terminals” or “Vesicle filled apposition” Unipolar Neurons - A single primary process extending from the soma - Common in invertebrates Bipolar Neuron - Two processes extending from the soma - Carries information toward the nervous system Multipolar Neuron → “Classic” Neuron - Multiple processes extending from the soma - Prevailing neuron within vertebrates - More dendritic branches = more connections to other neurons Synapse Breakdown Synapses occur between dendrites and axon terminals. Synaptic vesicles filled with neurotransmitters (chemicals containing the action potential) are released from the presynaptic membrane (axon terminal) into the synaptic cleft. These neurotransmitters then bind to specific corresponding receptors on the postsynaptic membrane (usually a dendrite or muscle). If neurotransmitters can not bind for whatever reason (inhibitors, not enough receptors, etc.), it will float around having no effect Impulses/Action Potentials We are already familiar with action potentials, polarization, and SIN POUT. Below are some extra tips to help solidify this material! Impulses are the result of an electrochemical reaction Sodium channels are initially opened by the binding of neurotransmitters Voltage = measure of potential energy; the higher the voltage, the higher the potential Absolute Refractory vs. Relative Refractory - Both occur during hyperpolarization. Relative can allow for action potentials to occur but it requires a stronger depolarization. Absolute means absolutely no action potentials! Signals During Synapses Postsynaptic potential → the positive shift in membrane potential on the receiving end Excitatory vs. Inhibitory PSPs - E → increases the likelihood of an action potential - I → decreases the likelihood of an action potential  Reuptake - Neurotransmitters are reabsorbed by the presynaptic membrane What are neurotransmitters? A fast form of chemical communication, separated into families based on their similarities - Typically large molecule or small molecules - Neurons contain billions of neurotransmitters (as seen in synaptic vesicles) - Contain a neuron’s “action potential” Agonists → a chemical that mimics the action of a given NT when binding to a receptor - Increase likelihood of action potentials Antagonists → a chemical that blocks a given NT when binding to a receptor - Decrease the likelihood of action potentials Small Molecule NTs Amino Acids - Glutamate Excitatory effects only; main excitatory transmitter for the brain Similarly to DA, can be damaging in high concentration - GABA Inhibitory effects only; main inhibitory transmitter for the brain Regulates sleep, anxiety, and arousal ie.) drugs for relaxation, anxiety relief Monoamines - Synthesized from tyrosine - Diffused throughout the brain - Dopamine (DA) Most well known NT Used by neurons that control voluntary movement Best known for its role in the brain’s “reward pathway” - Any good outcome triggers a release of dopamine Overactive synapses can lead to many problems ie.) schizophrenia, parkinson’s - Norepinephrine (NE) / Noradrenaline Functions as a hormone and NT for sleep, hunger, mood, sexual behavior Increased by amphetamines and methamphetamines Source of our fight or flight response - Serotonin (5-HT) Regulation of sleep, eating, aggression Not an explanation of all problems humans experience Second most well known NT due to SSRIs (treatment for mental disorders)  - SSRIs prevent reuptake of serotonin, increasing its concentration - Increased 5-HT effects are not instantaneous Acetylcholine (ACh) - First NT discovered - Found throughout nervous system - Released during muscle movements in both central and autonomic systems - Regulates attention, arousal, and memory Unconventional NTs - Anandamide (ananda: joy, delight) Binds to same receptors as THC (active ingredient in weed) Causes effects similar to weed Occurs in central and peripheral systems Inhibits pain if concentration is too high Large Molecule NT’s Neuropeptides - Endorphins (endogenous morphine) Mostly regulated by peripheral system through pituitary gland Acts as hormone and NT Discovered through study of opioids Inhibits communication of pain to spinal cord (natural painkiller) What is the endocrine system? A communication network of glands within our body that produce hormones through the bloodstream - Hormones → chemical messengers *These are similar to NTs but slower* Effects from this system are slower to generate but last longer The pituitary gland produces stand alone hormones and hormones that regulate other glands Neural Plasticity / Neuroplasticity The nervous system’s ability to change, evolve, develop over the course of an organism's lifetime - Adaptation plays a big role; we learn by adapting to new experiences and stimuli Role in Early Development (Pre-birth until early adulthood) - Neuroplasticity is very high here 1. Dendrite and Axon Growth → if not properly branched or elongated properly, neurons will have limited abilities  2. Synaptogenesis → formation of new synapses for chemical communication 3. Pruning (prior age 10) → brain disposes of unnecessary neurons to run more efficiently 4. Myelination → allows for faster impulses Role in Learning - Long lasting enhancement in signal transmission between neurons Potentiation of synapses → Presynaptic neuron is overpowered and increases the likeliness of the postsynaptic neuron picking up and passing along the message ie.) a democracy where one individual is overpowered Long term potentiation is whenever this phenomenon occurs for a long time - Increased growth of dendrites and axons due to new experiences Enrichment studies → studying the difference between two groups when manipulating ranges of experiences and stimuli Role Following Injury - The brain does not have the ability to self heal, rather it reorganizes itself Brain regions will take over functions previously performed by others - We are still trying to find ways to repair/prevent brain damage! Stem cells → cells that can self divide and become any cell *Offers treatment for parkinson’s, diabetes, blindness, etc. *Controversial due to destroying embryo to obtain cells Neurogenesis → creation of new neurons in the brain Composition of Your Brain Cerebral Ventricles → pockets in the brain that contain CSF - CSF protects and provides nutrients to the brain Meninges (DAP) - Protector of brain and spinal cord - Dura mater → thickest protective layer *Split into two layers containing oxygen depleted blood - Pia mater → layer that conforms to bumps and folds in brain *Subarachnoid space exists between P and A, containing CSF Franz Joseph Gall - Rejected the idea that the mind and body are distinct (monism) - First person to propose all mental functions emanate from the brain  - Argued that the brain is not one organ, but a system of many organs with distinct functions - His views were not backed by experimentation; he advocated by phrenology but many were not a fan of his work All regions and hemispheres of the brain work together Cerebral cortex → outermost layer responsible for higher order functions ie.) problem solving, language learning, sensory processing due to its lobes Frontal lobe - Language, movement, coordination, memory, personality - Divided from the Parietal lobe by the central sulcus - Prefrontal cortex (“frontiest” part) → planning and thinking Contains Broca’s area, which helps with speech production and comprehension Paul Broca discovered many patients with a damaged Broca’s area struggled with producing speech - Primary motor cortex → controls movement Known due to Wilder Penfield → applied shocks to motor cortex of patients which resulted in varied muscle movements - Specific areas of this cortex control specific body parts - Some areas (smaller, more refined muscles) require more motor control and take up more cortical space - Cortical Homunculus Parietal Lobe - Sensory information - Sends info obtained through our senses to the motor cortex - Somatosensory cortex → our “touch” sense *Specific areas of this cortex correspond to specific body parts Temporal Lobe - Processing of auditory information - Processing of language Wernicke’s area, located at the top of the temporal lobe, behind the left ear, is primarily responsible for this - Damage to this area results in impairment of speech comprehension, leaving individuals speaking simlish, however they do not realize they are doing so Autobiographical (personal) memory - Refers to one’s memory of personal events  - Studied by Penfield, in which his probing of this area resulted in patients experiencing vivid recollections ie.) the view from a window, a particular song - It is uncertain if these were really “memories” being probed or altered perceptions Memories are not stored recollections, rather they are interpretations of our experiences constructed by our brain Occipital Lobe Basal Ganglia → tells you what to do and how to to do it The Limbic System The limbic system regulates EMMO and the processing of internal states. It originally evolved from a primitive from the olfactory system! Thalamus - Located at the top of the brain stem, in the dead center of your brain - Composed of clusters of nuclei that act as a relay center for sensory info - All senses we experience must pass through the thalamus Information enters through sensory organs, travels through thalamus, and is sent to its corresponding lobe for processing! ie.) The mail room in an office building, which all mail must pass through before being distributed Hypothalamus - Located underneath the thalamus - Maintains homeostasis within the body - Responsible for the 4Fs, body temperature, hunger, emotions, sleep - Acts as a relay center for info between the CNS and endocrine system ie.) regulates the hormone production of the pituitary gland Hippocampus - Name originates from “horse” and “sea monster” - Hypothesized to be linked to the formation of new memories; damage to the hippocampus (ie. infection) results in difficulty creating memories ie.) Clive Wearing - Humans have two hippocampi, each playing a role in spatial memory  ie) remembering locations of objects, places events occurred, planning routes → taxi drivers in london are observed to have a larger hippocampus due to neuroplastic responses Amygdala - Name originates from “almond” → the almond shaped structures at the end of the hippocampi - Plays a key role in fear, arousal, and excitement Damage can result in lost ability to interpret the emotions behind different facial expressions Role in fear conditioning → humans learn to predict scary/dangerous events The Brain Stem Medulla Oblongata Pons → info relay center between the cerebellum and cerebral cortex Midbrain - Contributes to movement, tracking visual stimuli, and reflexive reactions Damage to midbrain will prevent reflexes Hindbrain → area that contains the pons, medulla and cerebellum - Cerebellum (NOT part of the brain stem!!) Responsible for coordination, motor control and fine motor tuning Has recently been linked to language, spatial abilities and executive functions (functions that allow us to use logic/reason) Helpers of The Brain! Reticular Formation - A cluster of neurons running upwards through the brain stem - Has recently been linked to many other functions (ie.) cardiovascular control, pain signals, etc.) - Responsible for reticular activating system Hypothetical arousal and consciousness system Spinal Cord - How the brain and body communicate  - Sensory neurons carry info from the body to the brain, whereas motor neurons carry info from the brain to the body - Interneurons speed up communication, connecting sensory and motor so the signal does not need to travel back up the the brain each time - SRSIMER Phrenology Most popular during the 1820s-1840s The idea that the brain can be divided into discrete sections, each responsible for particular psychological traits. Advocated for by anecdotes of amateur doctors who assumed they could extract information about these traits by examining the bumps on a person’s skull - A more pronounced section of skull indicated its corresponding region of the brain to be larger, thus making this trait more pronounced in one’s personality Not true at all - The brain is unable to “mold” the skull due to layers between itself and the skull, the brain is far too soft to modify the skull. Died as a theory due to being too falsifiable - Patients experiencing damage to certain sections of the brain did not experience psychological problems Assessing the Brain Studying how brain damage affects behavior is a better way to assess the structure and function of the brain and its regions. - Recall Paul Broca’s observations that damage to Broca’s area correlated to speech issues Stereotaxic methods - Uses a map of the brain, featuring a coordinate system - Head is strapped to device and brain is precisely lesioned using this coordinate system to assess issues such as strokes - After procedure is complete, subject is observed to see how the damage affects their behavior Stereotaxic methods on humans - Can be performed on humans awake during brain surgery - Prior to incisions being made, electrical stimulations are used to activate the region of the brain being operated on This is used to ensure that messing with that part of the brain will not damage any vital functions  Brain damage can be assessed through other, nonphysical means - Neuropsychological testing → analyzing a person’s ability to reason, hold focus, etc. - Score allows researchers to correlate brain damage to specific regions of the brain Electroencephalograph (EEG) *Recall Pinky Keen* - Electrical activity of the brain is recorded at the surface of the skull - Electrical activity is measured by electrodes placed on top of the skull, the EEG will spit out oscillations - Examining these obtained wave patterns allows examiners to determine which parts of the brain are active during certain tests - Pros Non-invasive for humans and animals Able to detect rapid and immediate shifts in electrical activity → high temporal resolution - Cons Low spatial resolution → can only capture activity from large areas, it is difficult to pinpoint the location of electrical activity with precision Transcranial Magnetic Stimulation (TMS) - Non-invasive - Applies a strong magnetic field to a localized region of the skull in order to create electrical fields in the brain These electrical fields will either excite or depress brain function in given regions This allows us to lesion the brain without physically doing so and make causal inferences Temporary effects Neuroimaging (Non-Functional Brain Scans) Provide structural information about the brain, but not how it functions Computed Tomography (CT aka CAT) - A series of x-ray scans assembled in a computer to produce a 3D representation of the brain - Requires harmful waves of radiation - Each new image progresses upwards from the base of the skull These combinations of x-rays from different areas provide us with much more detail than the typical x-ray  Magnetic Resonance Imaging (MRI) - Provides an image of the brain’s structure → a more crisp, detailed CT - More suited for detecting soft tissues ie.) Brain Tumors - Makes use of strong magnetic fields to indirectly visualize brain structure, rather than harmful radiation MRIs measure the release of energy from water within brain tissue when exposed to this field Functional Brain Scans Positron emission tomography (PET) - Invasive → injection of radioactive glucose like molecules - Typically combined with a CT scan to get a better image of the specific areas - Imaging technique which measures the consumption of glucose like molecules, providing a picture of neural activity in different regions of the brain Active neurons will increase their glucose consumption, areas with most glucose consumption are the most active Functional MRI (fMRI) In the 90s, researchers realized that as neuronal activity increases, oxygenated levels of blood increase → recall how neurons feed off oxygen - Uses magnetic to visualize brain activity by use of the BOLD response BOLD → Blood Oxygen Level Dependent - Measures indirect correlate of neural activity rather than neural activity itself - Produces highly detailed outputs of where blood flow occurs (MRI function) - Highly sensitive to motion - Can have many problems; proposes questions as: What is the BOLD response really indicating? Even if we assume the photos are an accurate depiction of neuronal activity, is this excitatory or inhibitory? What kinds of stat techniques should we use to estimate the BOLD response? - Unhighlighted areas are not inactive areas! Requires a collection of baseline activity in the brain, researchers then have subjects engage in a given task and measure the activity depicted there. The baseline activity is then subtracted from the total, allowing researchers to observe the areas of activation necessary to perform the given task. Neuroanatomical Techniques In which we are able to observe parts of the brain at a cellular level; neurons are packed so tightly together it can be hard to observe certain parts up close. Golgi Stain - Neural stain that completely darkens a few neurons in a slice of brain tissue, revealing their silhouettes - Discovered by Camille Golgi, who originally tried to stain the meninges. The stain leaked over to some neurons. - Despite the silhouette of the neurons, we are unable to analyze how many neurons are within that sample of brain tissue Due to the golgi stain only staining a few neurons Nissl Stain - First procedure known to rectify the issues within the golgi stain - Uses crystal violet to penetrate all of the cells within a brain sample - Highlights cell bodies → we are able to determine how many cell bodies there are Electron Microscopy - Makes use of the an electron microscope When using a normal microscope, we are limited by how many times we can magnify a sample - Brain sample is coated with an electron absorbing substance before shooting a beam of electrons through it onto photographic film This creates an electron micrograph which generates detailed images Topic 2: Sensation and Perception Illusions There are certain scenarios in which our subjective experience (perception) does not match the physical reality we are exposed to. Optical illusions can highlight interplay between multiple sensory systems - Multiple of our senses functioning at once can confuse each other ie.) Hearing the same sound while looking at two clips of a person moving their mouth in different ways Illusions exist within all of our senses and are what emphasize the importance of distinction between sensation and perception Sensation The mechanical process of our bodies detecting objective stimulation, transducing (converting) it into neural impulses, and passing these impulses to the brain. Viewed as the “signal” traveling through your body  Transduction → converting external energy (stimuli landing on receptors) into electrical activity within neurons - This is done to convert these energies into a “language” our neurons can understand Languages include: action potentials, neurotransmitters Sense receptor → specialized cells responsible for transduction of specific stimuli - The five senses ie.) the rods and cones in your eyes are responsible for vision Sensory (neural) adaptation → sensory receptors are most active upon initial detection of stimulus, slowly declining in responsiveness as time progresses ie.) when sitting, you first notice the feel of the chair against your butt, however you stop noticing it over time - Done to conserve energy and resources - Lack of this adaptation would result in sensory overload; leaving an organism unable to function - Responsiveness will return if another stimulus is applied ie.) someone mentioning the chair underneath your butt will draw your attention back to it Psychophysics Psychophysics is the study of how humans perceive stimuli based on physical characteristics of the stimuli. Emerged in the 1860s - In other words, studying determining factors for detecting or not detecting stimuli Absolute threshold → lowest level of stimulus an organism’s nervous system requires to detect a change in the stimulus at least 50% of the time ie.) A researcher plays some music in your headphones, later on asking you if you can detect any specific added tones. This determines how sensitive your auditory system is; if you can detect this tone 50% of the time, you are averagely sensitive. Just Noticeable Difference (JND) → smallest detectable change in a stimulus ie.) If your mom asks you to turn down your T.V, how much do you need to lower the volume for her to notice it has gotten quieter? - JND is calculated with Weber’s Law Demonstrates a constant proportional relationship in the measures between the JND and original stimulus intensity Calculated by JND = (K)(I) → in which I = OG intensity and K = constant Signal Detection Theory A theory that regards how stimuli are detected under different conditions  Developed to mathematically describe how we detect stimuli in different conditions Signal to noise ratio → ratio of power of a signal to power of background noise - Signal → stimulus desired to be perceived - Noise → everything else *Increased noise makes it harder to detect the signal* Accuracy → (Correct responses / Attempts)(100) - Four possibilities include a hit, miss, false alarm, correct rejection - Increased sensitivity to a signal corresponds with increased green - Decreased sensitivity to a signal corresponds with increased red Differences in these sensitivities are referred to as “d-prime” - Difference in probability of a hit and a false alarm - Measure of stimulus salience (prominence) - Increased value improves detection - Plotted using Receiver Operating Characteristic Curve) Viewing the outcomes of hits and false alarms in relation to each other Polygraphs The examiner needs to set a threshold for what is considered a “lie” - Results depend on criteria of examiners - Thresholds will often vary depending on the given circumstance Perception Perception is our brain’s interpretation of raw sensory information gathered from our sensory organs. This interpretation then manifests into a subjective experience. Determined by what is currently in the sensory field, what was in the sensory field a moment ago, and our past experiences. 3 Processes Parallel → the ability to attend to many sense modalities simultaneously - ie.) eating, smelling, and tasting food all at once Bottom Up → the brain constructs a whole stimulus from its individual parts - ie.) identifying objects by feel, smell, sound, etc. - Basic sets of stimuli are translated by the brain into a meaningful concept Top Down → conceptually driven processing influenced by beliefs or prior learning - Begins with prior information from learning, or what is currently known → information is then imposed on a given stimuli to make sense of it *Note: Top Down and Bottom Up are not always disjoint* Perceptual Set  In which our experiences influence our perceptions of a stimulus - Past learning experiences are generalized to a new scenario and a constant stimulus can yield different results Perceptual Constancy In which we perceive visual stimuli consistently across varied conditions - Aspects of the stimulus can change but the interpretation will remain the same *This is the inverse to a perceptual set *Note: perceptual sets and constancy provide a description of a phenomenon, they are not the cause or explanation for anything* Attention Selective Attention → selecting one sensory channel, and ignoring or minimizing others - Assumed to be controlled by the reticular activating system and higher cortical regions ie.) listening to an entire orchestra and only focusing on the clarinettes Inattentional blindness → failure to detect stimuli in plain sight due to our attention focusing somewhere else Change blindness → failure to detect changes in a visual stimulus Filter “theory” of Attention (Analogy) - Describes attention as a “bottleneck” in which information passes through - Assumes this cognitive bottleneck restricts information flow, which allows humans to pay attention to specific information Depicted in book by Daniel Broadbent His theory was tested by dichotic listening - A research design in which subjects wear headphones which play two simultaneous messages through different ears Demonstrates how your brain filters out unnecessary information → however we can still absorb some of this excess information, just significantly less than the information we are attending to Subliminal Messaging The idea that a person’s behavior can be altered by exposing them to stimuli they can only unconsciously perceive - Subliminal messaging can be “real” in the sense that the body can respond to stimuli the brain is not consciously aware of (perceiving stimuli) - Subliminals can not be “real” in the sense that you are persuaded by stimuli EX.) The Judas Priests - Demonstrates the legal controversy surrounding subliminal messaging  - Judas Priests were accused for causing teen suicides by means of “backmasking” → hidden, backwards messages Backmasking has no legitimate effect - The suicides were not widespread enough for there to be correlation between them and the albums produced by the band Satanic Panic (1980s-1990s) - Period of history regarding “demonic” bands and subliminals - The reason many albums contain parental advisory warnings PA warnings were a compromise for Al Gore and his wife, due to their desire to ban heavy metal music Extrasensory Perception (ESP) ESP is our perception of events outside the known channels of sensation. (Basically the ability to sense things through means of channels other than the five senses → “psychic powers”) Studied by parapsychologists → not a legitimate branch of psychology - Studied actively previously, some universities still offer this Pre Recognition → predicting events before they occur through paranormal means (no reliance on scientific methods) ie.) predicting what card will be chosen Telepathy → reading other people’s minds ie.) what is Carmille thinking? Clairvoyance → detecting the presence of objects of people hidden from view ie.) is Angie around that corner? While ESP sounds dubious, it is widely believed to be real, with around ⅔ of Americans claiming to have experienced it. Why? 1. Illusory correlation Humans dwell on coincidences, ignoring or forgetting events that do not conform to the correlation believed to exist - Our internal correlations are not updated when there is evidence that contradicts them ie.) Ghost Hunting Shows → when hunters perceive a “sign” they interpret it as evidence, ignoring all the evidence previously collected that combats their theories (failed attempts of communication) 2. Underestimating coincidences Coincidences are not nearly as rare or special as we believe them to be ie.) The Birthday Problem Joseph B Ryan During the 1930s, Ryan was the first to experiment with ESP Coined the term “extrasensory perception” Completed his studies with Zener cards, created by Carl Zenner Discovered his participants averaged ~6/25 cards correct - This statistic was higher than the predicted chance levels for the experiment (~5/25 correct) The problem with Ryan’s studies: Sampling error - Being above the predicted chance levels does not guarantee this is an unlikely event; there will always be random fluctuation ie.) flipping a coin may yield heads three times in a row, despite the coin being fair - His averages were not statistically compelling, due to the high sampling error (falling within 95% range) → to be statistically significant he would’ve required multiple observations falling within the 5% range (~8/25 correct or higher) Studies were not repeatable Did not swap out his Zener cards The Ganzfeld Technique According to proponents of ESP, “receivers” of ESP are like antenna for extrasensory input In this assumption, extrasensory input is a weak signal often obscured by stimuli in the environment → an explanation for why it was impossible to recreate Ryan’s results Ganzfeld technique attempts to cut receivers off from “sensory noise” within the environment, focusing only on the desired sensory input Subjects are placed in quiet rooms with eye coverings and headphones A red flood light is directed at subjects - Eye covers and flood light aim to induce a hallucinatory state; which is assumed to be more conducive to ESP reception Down the hall from the quiet room is a “sender” in another quiet room - Sender attempts to psychically transmit images to the receiver Receiver must then rate a series of pictures on how well they match their experience, sensing whatever the sender has transmitted to you Ganzfeld studies were studied by Daryl Bem and Charles Hanorton discovered the hit rate was higher than the expected chance This analysis was later proved to be inaccurate Bem wrote a paper on this, arguing subjects could predict the future → “Feeling the Future” - He was proved wrong The Visual System (Real Sensory Perception) Hue → the color of light Visible light → EMR between 400-700 nanometers (Nm) Humans are limited to what wavelengths of light we can perceive ie.) birds can perceive ultraviolet light Recall: when light reflects, only a portion of light is actually reflected, some light is always absorbed. White objects reflect all light that hits them Black objects absorb all light that hits them *These phenomena are why black and white are not viewed as colors → rather they are respectively viewed as the presence and absence of all colors* Color theory in regards to light differs from color theory in regards to paint ie.) mixing red, green, and blue paint will produce brown, whereas mixing equal parts of these lights together will produce white Additive color mixing → combining light to obtain new colors Subtractive color mixing → removing light to obtain new colors The Eyeball Myopia → nearsighted → cornea too long → light focuses in front of retina Hyperopia → farsighted → cornea too flat → light focuses behind retina Pupillary Reflex → a reflex from the pupil which alters the amount of light entering the eye - Lack of this reflex can imply neurological or eye-related damage - The reason why opticians shine bright lights in your eyes during a checkup The Lens - Uses accommodation to change shape and curvature - A flat, relaxed lens allows us to focus on distant objects - A fat, contracted lens allows us to focus on near objects Optic Nerve → Bundle of ganglion cells traveling from the retina to the brain - Visual signals travel down this nerve, eventually reaching the optic chiasm Optic chiasm → junction within the brain for visual signals - Information from the left visual field travels to the right hemisphere and vice versa The Retina → responsible for converting light into neural activity  - Photopigments → protein molecules within rods and cones, whose chemical reactions when absorbing light result in nerve impulses being generate - Contains rods and cones (photoreceptors) You have more rods than cones! Rods and Cones - Rods are long and narrow (similar shape to a rod) - At night, the fovea centralis becomes less responsive than rods Peripheral vision becomes better than central vision - Dark Adaptation → time in dark before rods regain maximum light sensitivity Around 30 minutes in a dimly lit environment Humans and Colour Hubel and Wiesel Discovered feature detector cells through the study of cat’s visual cortex in the 1960s - FDC → cells that detect lines and edges - FD → ability to respond to patterns and edges Surgically implanted electrodes in the V1 area of the visual cortex and recorded action potentials of specific neurons when cats were presented with different stimuli When presented with lines of specific orientations (vertical, horizontal, oblique) many V1 cells became active - Cells would only become active if this line was presented with the correct orientation and location of visual field *Indicated that some cells require more information than others* At later levels of visual processing, detector cells become more complex - Can detect shapes, colors, movements, depth etc. These are known as V2 cells Trichromatic Theory (1800s) → theory that our color vision is based on our sensitivity to the primary colors Corresponds to later findings that humans have three types of cone cells that respond maximally at different wavelengths (1960s) Short, Medium, Long - Cones in our eyes can be stimulated to greater or lesser degrees ie.) when staring at a blue object, blue cones will be most active Color perception determined by additive color mixing - Blending and combining wavelengths rather than absorbing wavelengths Can’t explain afterimages - After staring at one color for a prolonged time, looking away will produce an image of a different color - Explained by opponent process theory Opponent Process Theory → theory that humans perceive colors in pairs of opponent colors Humans have three receptor types, each with an opposing counterpart  - These receptors exist become activated when one color is presented, and inhibited when a different one is - Receptors activated by one color will be inhibited when presented with its opposing counterpart Red and Green Blue and Yellow Black and White - Explains afterimages → the result of receptors attempting to create an inhibitory response to the color we have been exposed to - Corresponds to findings of retinal ganglion cell functions which exhibit this behavior Ewald Hurling was very close to describing the real process, however he proposed that this process occurred within the cones (wrong location) Dual Process Theory What modern interpretations of color perception rely on A combination of Trichromatic and Opponent Process Gestalt Psychology Originated from a German Psychology School as a reaction to structuralism in the early 20th century - Rather than examining elements of consciousness separately, we should study the natural organization of these elements into patterns or “wholes” ie.) Do not examine individual brush strokes within a painting, rather focus on the whole image as well as its meaning and purpose Max Wertheimer, Wolfgang Kohler, Kurt Koffka Principles of Gestalt Psych 1. Proximity → objects physically close to each other are viewed as unified wholes 2. Similarity → similar objects are grouped together or seen as related 3. Continuity (good continuation) → lines are viewed as continuous movement, while discounting abrupt changes 4. Closure → the tendency to view incomplete figures or objects as complete 5. Symmetry → symmetrically arranged objects are viewed as wholes 6. Figure-ground segregation → the tendency to separate elements of an image into a foreground and background Gestalt principles show that the human brain is constantly searching for patterns; it will look for or impose patterns even when they do not exist - Humans lack at enacting random behavior Due to predictable events providing utility for humans → evolution has pushed humans to use this for survival Depth Perception Ability to judge distance and three dimensional relations  This is so we don’t walk into walls or do other silly things! Monocular cues → stimuli that enables us to judge depth using one eye - Relative size → distant objects look smaller than closer objects - Texture gradient → further away object is, less detail it has - Interposition → close objects block the view of distant objects - Linear perspective → outlines of objects converge as distance increases - Height in plane → distance objects tend to appear higher while closer objects appear lower - Light and Shadow → when objects cast shadow, this gives the object a 3D form - Motion parallax → objects moving across a field of view appear to move more/faster the closer they are to an observer Deals with angles, lines of sight - Can give the illusion of motion of an object that is stationary ie.) moving camera tracking a stationary car Binocular cues → stimuli that enables us to judge depth using both eyes - Binocular disparity → depth information obtained by comparing difference in the image location of our left and right eyes Each eye sends different information to the opposite hemisphere of the brain (right eye → left hemisphere, left eye → right hemisphere) The brain then compares the different information - The further the distance the observer is to an object, the larger the difference - Binocular convergence → degree to which the eyes converge inward provides information to estimate an object's distance Degree to which our eye muscles converge is tracked by the brain, which uses this information to estimate how far we are from an object. *Closer objects require more convergence* Blindness Color blindness (deficiency) → the inability to perceive all or some colors Due to a genetic abnormality in which a person is missing a specific cone type Dichromates → missing ⅓ cone types - Colton-esque vision Monochromats (extremely rare) → missing ⅔ cone cells - Black and white vision *Fun Fact: Color blind glasses don’t actually work* - It allows individuals to distinguish between different hues, yet they do not “perceive” the “real colors” Blindness → the inability to see due to problems with the eye or its related structures Exists on a continuum Visual cortex’s function will change due to neuroplasticity Agnosia → failure to recognize or name visually presented objects ie.) Oliver Sacks → the man who mistook his wife for a hat Not due to issues with memory or intelligence Due to damage to peripheral regions of the occipital lobe near the temporal and parietal lobes Motion blindness → neurological disorder in which people cannot perceive motion AKA: Cerebral Akinetopsia A person’s perception of motion is similar to a stop motion film/flip book - Movements are laggy and not smooth, similar to bluelock season 2 Often caused by brain damage or alzheimer’s Blindsight → individuals with blindness can detect and respond to visual stimuli Results from damage to V1 area of visual cortex ie.) Showing a person a red ball will result in them being unable to see it; throwing it at them will result in them catching it They “can see” but also “cannot see” Topic 3: Genes, Evolution, and Behavior The Basics of Genes Chromosome → thread-like X shaped structures which carry genes Gene → DNA that controls the synthesis of a given protein Genome → genotype (combination of genetic coding) Allele → variation or version of a genotype Polygenic transmission → in which a singular phenotype is controlled by more than one gene ie.) Hair color is not controlled by a single gene pair rather it is controlled by many Epigenetics The study of heritable changes in gene function due to environmental factors rather than the DNA sequence - A specific genotype can lead to different phenotypes depending on environmental conditions Diet, upbringing, exercise ie.) Identical twins will still have different life experiences, producing variability in their gene expression despite having the same genotypes (identical genotypes and different phenotypes) Darwin’s Theory of Natural Selection Genes are not fixed, they are susceptible to mutations - These mutations can either increase or decrease survival/reproduction rates; they can also have no reproductive advantages or drawbacks - This means no two individuals are 100% identical and why the characteristics of a species are observed to change over time Genetic Engineering Knockout Procedure → a technique in which a gene(s) is altered so that it does not perform its original function The targeted gene(s) become inoperative, aka knocked out * Note that genes can also be replaced, aka knocked in After the gene is knocked out we can compare the behavior of the KO’d animal to a normal animal to assess the gene’s role in a given behavior or phenotype The issue with KO - Behavior and phenotypes often depend on multiple genes - A singular gene can have multiple roles in various behaviors or phenotypes Results from KO are not straightforward or specific enough to attribute results to manipulation of the KO’d gene Observations can suggest that the KO’d gene plays a role in a given behavior or phenotype, but is not sufficient to account for observations on its own Behavioral Genetics Studied to estimate the heritability of traits, disorders, and diseases Heritability → the extent to which a trait’s variation within a population is due to genes - Estimated with the heritability coefficient (percents, proportions, probabilities) This estimate can only be applied to specific populations - Cannot make statements about individuals - Must only be applied to their receptive population in order to hold significance ie.) Studying intelligence of two groups of children in which group 1 is from a homogenous population of upper middle class children and group two is from a heterozygous group of mixed socioeconomic children → HC for group 1 will be much higher, given their environmental factors are identical Hereditary → passing of a trait from parents to offspring through genes Concordance → likelihood that two individuals share the same trait - Knowing the level of genetic similarity across family members allows for the estimation of relative contribution of hereditary and environmental factors to a trait - If concordance is higher among related individuals than unrelated individuals, this suggests a genetic contribution to a trait’s presence Family Studies Examining the degree to which a trait runs in intact families Useful for estimating the risk of particular disorders among relatives of members with the disorder Intact families can cause confusion as to whether the observed results are from shared genes or a shared environment → created a need for twin studies Twin Studies Monozygotic (identical twins) share 100% DNA Dizygotic (fraternal twins) share 50% DNA A pair of MZ and DZ twins are each observed within an intact family, in which both sets of twins grow up in a controlled, identical environment - Researchers then measure the similarity between each set of twins for a given trait - If the correlation/similarity between the MZ twins is higher than the DZ twins, we can infer that the given trait is genetically influenced MZ twins may be treated more similarly than DZ twins, meaning the environments are not controlled, furthermore we cannot determine if the results are due to genetic or environmental factors → created a need for adoption studies Adoption Studies “Gold standard” out of the three behavioral genetics studies Most difficult to conduct Adoption studies analyze how traits vary in individuals raised apart from their biological parents An adopted individual is studied for a specific trait - Shares genetic variables with their biological parents - Shares environmental variables with their adoptive parents If the individual is more similar to their biological parents in regards to the specific trait, the trait is assumed to be heavily influenced by genes and vice versa Can be ruined by selective placement - In which adoption agencies will select homes for children that are similar to their biological parents We may think a similarity can be attributed to genetic variables when it is caused by environmental variables Stat procedures are used in attempt to correct this Reaction Range The genetically influenced limits within which environmental factors can exert their efforts on an organism (range) - Inspired by the question, “how do genetics and the environment interact to produce behavior?” Genetic code provides the upper and lower boundaries for a given trait’s potential (range to which a trait can be minimized or maximized)  The environments and experiences an organism is exposed to determines where the trait will fall within the predetermined boundary - This placement cannot be measured directly Demonstrated through IQ studies - Children from impoverished environments are separated into two groups - Group 1 is located to enriched environments while Group 2 remains impoverished - Group 1 demonstrated a high increase in their IQ, whereas Group 2 remained stagnant or even worsened Evolutionary Psych Applies Theory of Natural Selection towards human and non-human animal behavior The idea that evolution selects not only physical, but behavioral traits to be passed down to offspring - Species typical behavioral patterns are the result of evolutionary pressures ie.) rats cautiously try new food in small bites, as to not be poisoned → allows them to survive and reproduce ie.) aggression allows us to compete for resources and survive The issue with evolutionary psych Unfalsifiable → there are no “fossils” or physical evidence of behavior being evolutionary Little is known about early humans - Evolutionary psych can only make assumptions about the past Multiple evolutionary explanations are often possible and can conform to any findings ie.) male pattern baldness serves an evolutionary function baldness must function as a trait of evolutionary maturity which attracts women Evolutionary explanations can account for any scenario given we lack sufficient findings from the past Referred to as “post hawk” or “double dipping” → makes assumptions after collecting data, using old data to make assumptions ie.) similar to shooting an arrow and drawing a bullseye around it; is not helpful