PSYCH 204 Experimental Psychology PDF

PSYCH 204 Experimental Psych. Second Sem. Krisette Romero, RPm What is an experiment? INTRODUCTION/OVERVIEW Lesson overview The term experimental psychology used to denote only a few selected topics in psychology. In, say, 1930, experiments were conducted to understand sensation,...

PSYCH 204 Experimental Psych. Second Sem. Krisette Romero, RPm What is an experiment? INTRODUCTION/OVERVIEW Lesson overview The term experimental psychology used to denote only a few selected topics in psychology. In, say, 1930, experiments were conducted to understand sensation, perception, learning, memory, and a few other topics. The situation is quite different today: Experimental methods are used to investigate social psychology, developmental psychology, individual differences, and many other topics (such as environmental psychology) that were not considered in psychology’s vision eighty years ago. The use of experimental methods has expanded to include most topics in the field. An experiment is a type of study designed specifically to answer the question of whether there is a causal relationship between two variables. In other words, whether changes in an independent variable cause changes in a dependent variable. Learning objectives Define an experiment. Understand Experimental Psychology. Understand the Scientific Method and its Steps. Know the different types of Experiments. Understand the Experimental Process.  What is an Experiment? an experiment is a type of study designed specifically to answer the question of whether there is a causal relationship between two variables. Experiments have two fundamental features. The first is that the researchers manipulate, or systematically vary, the level of the independent variable. The different levels of the independent variable are called conditions. The second fundamental feature of an experiment is that the researcher controls, or minimizes the variability in, variables other than the independent and dependent variable. These other variables are called extraneous variables. Experimental Psychologists Experimental psychologists are interested in exploring theoretical questions, often by creating a hypothesis and then setting out to prove or disprove it through experimentation. They study a wide range of behavioral topics among humans and animals, including sensation, perception, attention, memory, cognition and emotion. Example of Experiments Experimental Psychology Applied Experimental psychologists use scientific methods to collect data and perform research. Often, their work builds, one study at a time, to a larger finding or conclusion. Some researchers have devoted their entire career to answering one complex research question. These psychologists work in a variety of settings, including universities, research centers, government agencies and private businesses. The focus of their research is as varied as the settings in which they work. Often, personal interest and educational background will influence the research questions they choose to explore. In a sense, all psychologists can be considered experimental psychologists since research is the foundation of the discipline, and many psychologists split their professional focus among research, patient care, teaching or program administration. Experimental psychologists, however, often devote their full attention to research — its design, execution, analysis and dissemination. Those focusing their careers specifically on experimental psychology contribute work across subfields. For example, they use scientific research to provide insights that improve teaching and learning, create safer workplaces and transportation systems, improve substance abuse treatment programs and promote healthy child development. The Scientific Method The goal of scientific psychology is to understand why people think and act as they do. In contrast to nonscientists, who rely on informal and secondary sources of knowledge, psychologists use a variety of well-developed techniques to gather information and develop theoretical explanations. As one example of this scientific approach to understanding, consider the following case study of the research process. The scientific method is essentially a step-by- step process that researchers can follow to determine if there is some type of relationship between two or more variables. Psychologists and other social scientists regularly propose explanations for human behavior. Objective and systematic way. Concept: Social Loafing The evidence from the experimental studies points to diffusion of responsibility as a possible reason for social loafing. People working by themselves think they are responsible for completing the task; when they work in groups, how- ever, this feeling of responsibility diffuses to others. The same idea accounts for behavior in other group situations: If one of your professors asks a question in a class containing only two other people, you would probably feel responsible for trying to answer. However, if there were two hundred other people in the class, you would likely feel much less responsible for answering. Similarly, people are more likely to help in an emergency when they feel the burden of responsibility than when there are several others about who could help. The Scientific Method (cont.) The scientific method is a valid way to acquire knowledge about the world around us. What characteristics of the scientific approach make it a desirable way to learn about and arrive at beliefs about the nature of things? Perhaps the best way to answer this question is to contrast science with other modes of fixing belief, since science is only one way in which beliefs are formed. More than one hundred years ago, the American philosopher Charles Sanders Peirce (1877) compared the scientific way of knowing with three other methods of developing beliefs. He called these the authority, tenacity, and a priori methods. Authority Tenacity A priori The Scientific Method (cont.) The last of Peirce’s methods, the scientific method, fixes belief on the basis of experience. Science is based on the assumption that events have causes and that we can discover those causes through controlled observation. This belief, that observable causes determine events, is known as determinism. If we define scientific psychology (as well as science in general) as a repeatable, self-correcting undertaking that seeks to understand phenomena on the basis of empirical observation, then we can see several advantages to the scientific method over the methods just outlined. Let us see what we mean by empirical and self-correcting and examine the advantages associated with those aspects of science. 2 Advantages: Empirical – Having an empirical basis for beliefs means that experience rather than faith is the source of knowledge. It offers procedures for establishing the superiority of one belief over another. Persons holding different beliefs will find it difficult to reconcile their opinions. Empirical, public observations are the cornerstone of the scientific method, because they make science a self- correcting endeavor. Nature of the Scientific Explanation What is a theory? -- A theory can be crudely defined as a set of related statements that explains a variety of occurrences. Theory in psychology performs two major functions. 1. Provides a framework for the systematic and orderly display of data—that is, it serves as a convenient way for the scientist to organize data. 2. Second, it allows the scientist to generate predictions for situations in which no data have been obtained. Theories are devised to organize concepts and facts into a coherent pattern and to predict additional observations. Sometimes the two functions of theory—organization and prediction— are called description and explanation, respectively. Explanations are tentative; nevertheless, the scientist still needs to decide which theory is best for now. To do so, explicit criteria are needed for evaluating a theory. Four such criteria are parsimony, precision, testability, and ability to fit data. Nature of the Scientific Explanation Basic elements in science: data (empirical observations) theory (organization of concepts that permit prediction of data) Approaches: induction, in which reasoning proceeds from particular data to a general theory. deduction, reasoning proceeds from a general theory to particular data. From Theory to Hypothesis Theories cannot be tested directly Scientists perform experiments to test hypotheses that are derived from a theory. A hypothesis is a very specific testable statement that can be evaluated from observable data A generalization is a broader statement that cannot be tested directly. Hypotheses vs. Generalization Hypothesis For example, we might hypothesize that drivers older than sixty-five years would have a higher frequency of accidents involving left turns across oncoming traffic when driving at night than do younger drivers. By looking at police records of accident data, we could determine, with the help of some statistics (see Appendix B), if this hypothesis is incorrect. Generalization For example, we might generalize that older drivers are unsafe at any speed and should have restrictions, such as not being able to drive at night, on their driver’s license. Since “unsafe at any speed” is not clearly defined, this is not a testable statement. Similarly, the generalization does not define an age range for older drivers. However, it can be used to derive several testable hypotheses. Evaluating theories Parsimony The fewer the statements in a theory, the better the theory. Precision Theories that involve mathematical equations or computer problems are generally more precise, and hence better, than those that use loose verbal statements (all other things being equal, of course). Unless a theory is so precise that different investigators can agree about its predictions, it is for all intents and purposes useless. Testability The scientist places a very high value on the criterion of testability, because a theory that cannot be tested can never be disproved. Ability to fit data Finally, a theory must fit the data it explains. While goodness of fit is not a sufficient criterion for accepting a theory, there is little point in pursuing a theory that fails to fit the data. Intervening Variables The IV and DV Independent variables are those manipulated by the experimenter. For ex- ample, not allowing rats to have any water for several hours would create an independent variable called hours of deprivation. Dependent variables are those observed by the experimenter. For example, one could observe how much water a rat drinks. Intervening variables are abstract concepts that link independent variables to dependent variables. Intervening Variables The first arrow relates hours of deprivation to thirst, an intervening variable. The second arrow relates the intervening variable, thirst, to the rate of bar pressing. Since the indirect method is more complicated, requiring an extra arrow, you might expect the scientist to prefer the direct method of explanation. Indeed, if the only scientific goal were to relate hours of deprivation to rate of bar pressing, you would be correct because science prefers simple explanations to complex explanations. How- ever, as we shall explain, the scientific goal is more general. Relates two independent variables, hours of deprivation and feeding dry food, to two dependent variables, rate of bar pressing and volume of water drunk. Again, both direct and indirect explanations are shown. Intervening Variables Relates three independent variables, hours of deprivation, feeding dry food, and saline injection (giving a rat saltwater through a tube inserted in its stomach), to three dependent variables, rate of bar pressing, volume of water drunk, and amount of quinine required to stop the rat from drinking. Again, both direct and indirect explanations are shown. Now, it is obvious that the indirect method is less complicated. It requires six distinct arrows, whereas the direct method requires nine arrows. So as science tries to relate more independent and dependent variables, intervening variables become more efficient Nature of the Scientific Explanation Step 3. Step 1. Step 2. Test your Make an Ask a Question Hypothesis and Observation Collect your Data Step 4. Step 5. Examine the Report the Results Results and Draw Conclusions Scientific Psychology Types of Scientific Research: Applied research aims at solving a specific problem—such as how to cure bedwetting—whereas basic research has no immediate practical goal. Types of Experiments: Lab Experiments Lab experiments are very common in psychology because they allow experimenters more control over the variables. These experiments can also be easier for other researchers to replicate. The problem, of course, is that what takes place in a lab is not always identical to what takes place in the real world. Field Experiments Sometimes researchers might opt to conduct their experiments in the field. For example, let's imagine that a social psychologist is interested in researching prosocial behavior. The experimenter might have a person pretend to faint and observe to see how long it takes onlookers to respond. Scientific Psychology Quasi-Experiments While lab experiments represent what are known as true experiments, researchers can also utilize a type known as a quasi-experiment. Field experiments can be either quasi-experiments or true experiments. Quasi-experiments are often referred to as natural experiments because the researchers do not have true control over the independent variable. Instead, the treatment level is determined by the natural conditions of the situation. A researcher looking at personality differences and birth order, for example, is not able to manipulate the independent variable in the situation. Treatment levels cannot be randomly assigned because the participants naturally fall into pre-existing groups based on their birth order in their families.  Concept: False Consensus Effect False Consensus Effect Background and Evidence The false consensus effect was first described by social psychologists in 1977. In one of the first research projects demonstrating the effect, researchers approached college students as they walked across campus and asked the students to advertise a restaurant by wearing a large sign that said, “Eat at Joe’s.” As you might expect, some of the students agreed to wear the sign, while others did not. All the college students were later asked how many other students they estimated would make the same decision they did (either to wear the sign or not to wear the sign). The false consensus effect was demonstrated when two results occurred: First, the students who agreed to wear the sign reported they believed that more than half of the other students on campus (62%) would also agree to wear the sign. However, the students who did not agree to wear the sign reported they believed that more than half of the other students on campus (67%) also would not agree to wear the sign. Thus, both groups of students, those who agreed and those who disagreed to wear the sign, overestimated how many other students would behave just as they did. False consensus effect. the tendency to assume that one’s own opinions, beliefs, attributes, or behaviors are more widely shared than is actually the case. A robustly demonstrated phenomenon, the false-consensus What do you think could be the implications of this effect? effect is often attributed to a desire to view one’s thoughts and actions as appropriate, normal, and correct. (APA Dictionary) Research Techniques (Overview) Naturalistic observation typically involves the un- obtrusive (nonreactive) observation or unobtrusive measurement of events naturally occurring in the environment. A case study, which usually involves the detailed examination of one individual, but it may also involve a comparison of a small number of individuals. Surveys gather detailed, self-reported information from a large number of individuals. Relational research attempts to show how variables are related to one another. Contingency research tries to determine whether the value of one variable depends on the value of another. The correlational research allows one to establish the amount of relation between two variables, which is useful for prediction. The Experimental Process Psychologists, like other scientists, utilize the scientific method when conducting an experiment. The scientific method is a set of procedures and principles that guide how scientists develop research questions, collect data and come to conclusions. The four basic steps of the process are: 1.Forming a Hypothesis 2.Designing a Study and Collecting Data 3.Analyzing the Data and Reaching Conclusions 4.Sharing the Findings