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Basics of Scientific Inquiry. Common sense claims Common sense claims are often hunches based on anecdotal evidence: e.g. most people would not hurt another.

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Presentation on theme: "Basics of Scientific Inquiry. Common sense claims Common sense claims are often hunches based on anecdotal evidence: e.g. most people would not hurt another."— Presentation transcript:

1 Basics of Scientific Inquiry

2 Common sense claims Common sense claims are often hunches based on anecdotal evidence: e.g. most people would not hurt another human being just because an authority figure told them too. – Milgram’s (1966) famous experiment into conformity. – Approx 70% of those tested gave ‘electric shocks’ to what they believed was another test subject, at a level high enough to kill them. – Before carrying out the research, Milgram had asked other psychologists whether he should go ahead with the experiment. He was told that nearly all participants would withdraw before causing any ‘pain.’

3 Three lessons from Milgram Skepticism is valuable. Skepticism is valuable. Careful observation under controlled conditions is very important. Careful observation under controlled conditions is very important. Observer expectancy results are real and are research cancer. Observer expectancy results are real and are research cancer. – Clever Hans wasn’t so clever, after all.

4 What Is Scientific Inquiry? Four goals of scientific inquiry: Description (what happens) Description (what happens) Prediction (when it happens) Prediction (when it happens) Causal control (what causes it to happen) Causal control (what causes it to happen) Explanation (why it happens) Explanation (why it happens) How would we apply these goals to the study of the effects of alcohol intoxication?

5 An open mind and good imagination are not enough. Research in the psychological sciences requires a skeptical attitude and objective methodology.

6

7 Falsifiability The case of blood-letting The case of blood-letting For a theory to be useful, the predictions drawn from it must be specific. For a theory to be useful, the predictions drawn from it must be specific. – Tell us what will happen – Tell us what will not happen – How would we test for my ability to mind read?

8 The Bottom Line Progress occurs in science when a theory does not predict everything. Progress occurs in science when a theory does not predict everything. Rather, science benefits from specific predictions about phenomena, made in advance. Rather, science benefits from specific predictions about phenomena, made in advance. Falsifiability is liberating – making mistakes furthers progress Falsifiability is liberating – making mistakes furthers progress

9 Falsifiable or Unfalsifiable? Pepsi tastes better than Coca Cola Pepsi tastes better than Coca Cola Psychics can speak to the dead Psychics can speak to the dead Aliens abduct us, do medical experiments on us and then return us, leaving no evidence Aliens abduct us, do medical experiments on us and then return us, leaving no evidence

10 A theory with the empirical “trappings” of real science, including a system of theoretical concepts and a wealth of corroborating evidence. But a pseudo-science has built-in “defense mechanisms” against possible refutation. The Freudian theory provides an interpretation for every conceivable symptom of the patient. Its “predictions” therefore can never be refuted. Pseudoscience

11 The Nature of Science – Order: there are regular patterns in events – Determinism: events have identifiable causes – Empiricism: theories should be based on publicly available evidence gathered through objective observation – Parsimony: explanations should explain as much as possible as simply as possible

12 A rule in science and philosophy stating that entities should not be multiplied needlessly. This rule is interpreted to mean that the simplest of two or more competing theories is preferable and that an explanation for unknown phenomena should first be attempted in terms of what is already known. Also called law of parsimony. Ockham's Razor

13 The Empirical Process

14 Building a Psychological Science Facts: Facts: – objective statement, based on direct observation, reasonable people agree with Theories: Theories: – Interrelated set of concepts designed to explain existing facts & generate new predictions Hypotheses & Specific Predictions: Hypotheses & Specific Predictions: – Predictions about new facts based on the theory

15 The Methods of Psychological Science

16 An Experiment Involves Manipulating Conditions Manipulating independent variables and measuring dependent variables helps to establish causal relationships Manipulating independent variables and measuring dependent variables helps to establish causal relationships Random assignment helps create equivalent groups Random assignment helps create equivalent groups

17 Types of Reasoning

18 Deductive Research A top down approach GENERAL SPECIFIC IF: All oranges are fruit and all fruit grows on trees THEN: oranges grow on trees Deductive process- Reasoning from general to particular. E.g. Start with a theory & look for instances that confirm this (deduction).

19 A bottom up approach GENERALSPECIFIC Inductive process- Reasoning from particular to general E.g. Scientists may observe instances of a natural phenomenon and derive a general law (inductive) Inductive process- Reasoning from particular to general E.g. Scientists may observe instances of a natural phenomenon and derive a general law (inductive) Inductive Research

20 Inductive or Deductive? Dan is a liar so I predict that the next thing he says will be a lie Dan is a liar so I predict that the next thing he says will be a lie Bubba has seen his puppy gnaw on shoes so he predicts that puppies always gnaw on shoes Bubba has seen his puppy gnaw on shoes so he predicts that puppies always gnaw on shoes Robins have nested under Ray’s carport for 3 years. He expects that they will nest there again this year. Robins have nested under Ray’s carport for 3 years. He expects that they will nest there again this year. The gene for blue skin in fish also codes for aggression so Jane will not put her blue fish in with Elaine’s red fish. The gene for blue skin in fish also codes for aggression so Jane will not put her blue fish in with Elaine’s red fish.

21 The Experiment

22 Independent Variables are Manipulated by Experimenters Experimenter control is the central feature of IV’s Experimenter control is the central feature of IV’s IV’s are NOT free to vary; instead, they are fixed by design IV’s are NOT free to vary; instead, they are fixed by design

23 Dependent Variables are Measured in Relation to IVs DV’s are said to depend on, be effects of, or be caused by IVs DV’s are said to depend on, be effects of, or be caused by IVs DV in alcohol intoxication study? DV in alcohol intoxication study?

24 Identify the IV and DV Jack does an experiment to determine whether alcohol makes fish more aggressive Jack does an experiment to determine whether alcohol makes fish more aggressive Jane puts more water in the dough of her bread in order to make it rise better Jane puts more water in the dough of her bread in order to make it rise better Martha gives her crying baby a popsicle because she thinks she may be teething Martha gives her crying baby a popsicle because she thinks she may be teething Dr. Smith shows people violent movies and measures how quickly they eat a meal afterward Dr. Smith shows people violent movies and measures how quickly they eat a meal afterward Wanda puts one orchid in the sun and one in the shade because she wants to decrease growing time Wanda puts one orchid in the sun and one in the shade because she wants to decrease growing time

25 An Experiment Involves Manipulating Conditions Manipulating independent variables and measuring dependent variables helps to establish causal relationships Manipulating independent variables and measuring dependent variables helps to establish causal relationships Random assignment helps create equivalent groups Random assignment helps create equivalent groups

26 List of Core Features of Experimental Methods: Independent variables (IV’s) Independent variables (IV’s) Dependent variables (DV’s) Dependent variables (DV’s) Random sampling from representative populations Random sampling from representative populations Random assignment to conditions or treatments Random assignment to conditions or treatments Efforts to “control” or minimize extraneous/irrelevant factors Efforts to “control” or minimize extraneous/irrelevant factors

27 Operational Definition The quantification of a variable that allows it to be measured The quantification of a variable that allows it to be measured Concepts in scientific theories must in some way be grounded in, or linked to, observable events that can be measured Concepts in scientific theories must in some way be grounded in, or linked to, observable events that can be measured Preexisting bias problem Preexisting bias problem

28 Class Activity

29 James Randi The Amazing Randi The Amazing Randi Paranormal 1 million dollar challenge Paranormal 1 million dollar challenge wMmNRIVc wMmNRIVc


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