The scientific methodGoals of the scientific methodThe structure of scientific theoriesWhat makes for a good theory?Where do scientific theories come from?PSYC 201Psychology and scienceThe scientific method- Not a specific formula or recipe for producing information. It’s a set of tools, it’s a strategy for producing and evaluating information.- One way to get a sense of what the scientific method is, is to contrast it with non-scientific approaches.1. General approach:Nonscientific: intuitive. People’s everyday decision making is prone to a number of different biases. Availability heuristic. People don’t know that their decisions are based on incorrect information.Scientific approach: Empirical. Decisions are based on direct, recorded observations. Intuition may be a very valuable source of new ideas, but these ideas are then tested.Ex. Not in book. Are there more words that begin with the letter R or words that have the letter R as the third letter? More with R as the third letter! The Availability Heuristic (Tversky and Kahneman, 1973). It’s easier to think of words that begin with R so we assume that there are more of them.Ex. Are older drivers more likely to be involved in traffic accidents? Intuitively, yes, because their perceptual abilities are clearly not as good, their reaction times are slower, and they can’t pay attention to as many things as once. Empirically, no.2. Observation:Nonscientific: Casual, uncontrolledScientific: Systematic, controlledIs it possible to be sure why a particular event is occurring? Does caffeine have an effect on memory. Could you tell from just making observations of people? What if you do an experiment. Big dose vs no dose. Big dose – remember fewer words from a list. But you find that the Big dose group has an average age of 74. The other group has an average age of 27. The experiment is systematic, but it not well controlled.Systematic: set up a standard condition to observe the behavior. Control: Eliminate other possible explanations for a differences in behavior.The variable you’re observing is called the dependent variable.The variable you’re manipulating is called the independent variable.Experimental condition: the presence of the explanation being examinedControl condition: the absence of the explanation being examined.Sometimes the independent variable is not being manipulated per se by the investigator. You could say that nature has done the manipulating. Here the independent variable might be an individual difference variable. For example you could look at whether age has an effect on memory. If you compared younger adults to older adults, age would be an example of an individual difference variable.In this example, age is a variable being controlled for.[Spot the I.V., the D.V., the control variable. Is the I.V. manipulated or an individual difference variable?]3. ReportingNonscientific: Biased, subjectiveScientific: Unbiased, objectiveExample, do younger adults tailgate more than middle-aged drivers? Or do some people just notice it more. They have a previous bias. Every time they see a younger tailgater, this just confirms what they already know to be true. So do a study where all the observers agree on a set of rules for judging whether or not tailgating has taken place. Agree on an operational definition of tailgating. At a certain speed, how close should the car be. The reporting of the results is made in such a way that anyone else could go and do the same study themselves. Different people, regardless of their personal biases, should be able to get the same results.4. ConceptsNonscientific: Ambiguous, with surplus meaningScientific: Clear definitions, operational specificityEx. The concept of intelligence. What is it? It’s an extremely difficult question. It wouldbe very easy for two people to use the same word, but mean different things. One way to resolve ambiguity is to provide an operational definition of the concept. Anoperational definition basically answers the question, “How do we measure it”? So, given the approach, intelligence is what intelligence tests measure. It’s a way for people to agree on what they’re talking about.Problem: just because you decide to measure intelligence in a certain way, this doesn’t mean that you’re necessarily measuring intelligence. Francis Galton measured the size ofpeople’s skulls, and said that he was measuring intelligence.5. Instruments:Nonscientific: Inaccurate, impreciseScientific: Accurate, preciseReaction time: estimate the reaction time versus have the computer measure the amount of time.6. Measurement: XXXXXXXXNonscientific: Nor valid or reliableScientific: Valid and reliableReliability refers to the consistency of the measurement. One sense of the term consistency is if you the measure the same thing twice, do you get the same answer. A second sense is whether the test is measuring more than one thing. If you have a questionnaire measure of depression, is it really only measuring that one concept or are other things getting in there as well. If you have a questionnaire, are all the items aiming at the same concept.Validity refers to whether a test measures what it’s supposed to measure. Galton’s measure of intelligence (head size) wasn’t valid. It was highly reliable, but not valid.7. Hypotheses:Nonscientific: UntestableScientific: TestableOne of the marks of a good theory is that it’s possible to test it. There are theories where you can interpret any possible observation in terms of that theory. One criticism of Freud’s theory is that it can explain practically any behavior after the fact. If they do one thing, they’re fixated at the anal stage of development. If they do the other thing, they have an unresolved oedipial complex. It isn’t possible to think of a behavior in a situation that doesn’t fir with some aspect of his theory.8. Attitude:Nonscientific: Uncritical, acceptableScientific: Critical, skepticalScience is a lot like adolescence. Adolescents do things just because their parents told them to do it. They do things because they’ve thought about it for themselves.Scientists don’t believe things just because someone else told them to. They aren’t very likely to believe something just because someone in authority told tem to. Scientists take the testability of scientific theories seriously in that in order for a scientific theory to widely