Unit Zero: Introduction to Psychological Science
0.1. The Scientific Attitude
Science is not defined by its subject matter, but by method—the scientific method.
You witness a phenomenon (UFOs or example).
You think of an explanation for the phenomenon (alien invaders).
You test the phenomenon either experimentally or observationally.
Your explanation (or hypothesis) is either supported or not. If it is not supported, your thesis is wrong. If it is supported, it might be right. A scientific attitude seeks evidence to support or not support an idea.
Richard Feynman on the Scientific Method and Scientific Attitude
If a proposal cannot be tested and potentially falsified, it isn’t scientific.
0.2. Psychological Science
People have been thinking about and trying to understand the human psyche for a very long time, but for most of that time psychology existed within the realm of philosophy.
Socrates: Begin with doubt. Socratic Questioning is a structured form of inquiry that leads us to doubt what we think we know and to come closer to the truth. For Socrates the goal of philosophy was to “Know Thyself” which is accomplished through questioning.
Plato (a student of Socrates): Individuals have innate knowledge. The role of the teacher is to draw out this knowledge through questioning.
Aristotle (A student of Plato): Rejected Plato’s idea of innate knowledge. We are born with a blank slate—knowing nothing but with a capacity to learn. We become what we learn to be, whether a king, a warrior, a philosopher, a saint, or a thief.
Plato and Aristotle reflect the ongoing debate between nature and nurture in psychology.
Hippocrates: the four humors:While the humoral theory has been found to be without evidentiary support, it is in fact “scientific” in that it can be tested against experiment and observation.
We usually attribute Wilhelm Wundt (1832-1920) a physiologist, with first application of scientific method to psychology.
1873—publication of Principles of Physiological Psychology.
1879—the first psychological laboratory at the University of Leipzig
Use of Introspection to understand human consciousness.
Edward B. Titchener (1867-1927), a student of Wundt employed introspection in the laboratory to break complex experiences into their simple sensory constituents from which he developed a theory of Structuralism.
While Structuralism did not survive Titchener’s death, his influence was profound. He brought Wundt’s scientific approach to psychology to the United States. He established a graduate program in psychology at Cornell whose graduates established programs in many other American universities.
Charles Darwin is not best known for his contributions to psychology, but his theory of natural selection has had a profound impact on psychology (and all of the life sciences). Darwin proposed that individuals are born with small differences that render them either more or less likely to survive and produce offspring. Those differences that increase the chances of survival are passed on genetically (about which Darwin was unaware) to succeeding generations which have more offspring.
Psychological traits (such as our tendency to duck when we hear a loud, unexpected noise) served an important function for our ancient ancestors and perhaps for us.
William James (1842-1910) developed a theory of functionalism in psychology. He was not interested in the basic structure of consciousness but in the role it played in the human experience.
Other schools of thought will develop from the conflict between these two including: Behavioralism, Psychodynamic Theory, Humanistic Theory, . . .
0.3. Scientific Method:
Begins with a question. The question may be fundamental to the nature of the mind and matter, or it may be as simple as “Will this new drug be safe and effective in curing or preventing a particular disease.”
The researcher develops a hypothesis: Yes, this new drug will, in a specified set of circumstances, increase the average survival rate of patients suffering from a specific disease by a statistically significant amount.
The researcher designs an experiment to test the hypothesis. In psychological or medical research, a sample set of subjects is selected. If the researcher is studying how fifth graders learn under different conditions, she might like to subject all fifth graders in the world to her experiment. This is impossible, so a representative sample of fifth graders must be selected. This sample should be large enough to indicate that the results can be applied to the whole population. It must be selected to avoid sample bias. For example, a group of one hundred fifth grade boys from the same school would not be representative of the total population of fifth graders. The goal of experimental design is to exclude all of the variables except for the one variable being tested.
0.4. Correlation and Experimentation
Selecting a sample population and exposing all of them to the same variables would not demonstrate anything. The experimental sample (whether mice or fifth graders), have to be divided into groups that are essentially similar. One group (the test group) will receive the experimental “treatment.” A second group might receive a placebo. A third group might receive no treatment at all.
If all of the subjects in the experimental group die while none of the subjects in the placebo and non-treated groups die, then the experimenter has shown perfect correlation between treatment and dying. She will also be facing some serious questions. This is why so many experiments involve mice, rats, fruit flies, and rhesus monkeys.
In many cases, it is not possible to show that the effect (whatever it is) is caused by the treatment. Many medicines taken by millions of people have been shown to be effective and safe even though it is not at all clear how they work. In this case the researcher can show correlation but not causation. Correlation means that any difference between the treated and untreated groups cannot be attributed to chance. Experimenters, of course, want to demonstrate that the differences between treated and untreated groups are a result of a specific cause.
0.5. Research Design and Ethics in Psychology
Many of the psychology experiments that are presented in General and Social Psychology textbooks cannot be repeated (which is normally a requirement of the scientific method), because they violate the ethical standards of the medical and psychological professions. Any human research must generally adhere to universal ethical standards. Institutional Review Boards at the university, hospital, or research facility must be persuaded that the experiment as designed will adhere to these guidelines.
Participation must be voluntary. Participants cannot be coerced into taking part in an experiment.
Participants must give informed consent. They must be told of the purpose of the experiment and any risks involved. In some circumstances it is permissible to use deception in an experiment, but only if the information to be gained cannot be had in any other way.
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0.6. Statistical Reasoning:
Descriptive statistics—use of numerical data to describe the characteristics of a group.
Measures of Central Tendency: mean, median, mode
Outliers and their impact on central tendency
Standard Deviation and Range: measuring the variation in a set.
Correlation Coefficient:
-1 (strong negative relationship—as X increases, Y decreases)
+1 (strong positive relationship (as X increases, Y increases)
0 (no relationship—random)
Skews and frequency distribution
Normal Distribution (bell shaped),
Bimodal (two groups)
Positively skewed
Negatively skewed
Longitudinal Studies: Studying a single group over a long period of time.
The Harvard Men’s Study (TED Talk)