Chapter 1 Psychological Science The Need for Psychological Science

How do we know what we know? How do you know that George Washington was the first President of the United States? How do you know that you really have a stomach? What makes you sure the sun will rise tomorrow? How do you know the color of the shirt you are wearing? How can you be sure there aren’t little creatures inside a computer that make it work?

How do we know what we know? Authority – we take the word of an expert Reason – deductive an inductive thinking to arrive at a conclusion Observation – your own experience All three ways of knowing are used by scientists, but observation must be the basis for knowledge that is scientific

The Limits of Intuition  Hindsight Bias  We tend to believe, after learning an outcome, that we would have foreseen it  the “I-knew-it-all-along” phenomenon  Overconfidence  We tend to think we know more than we do  Confirmation Bias  Our tendency to seek out information that confirms our previous beliefs and to ignore information that refutes them.

The Scientific Attitude  Critical Thinking  thinking that does not blindly accept arguments and conclusions  examines assumptions  discerns hidden values  evaluates evidence

The Scientific Method  Theory  an explanation using an integrated set of principles that organizes and predicts observations  Usually a statement about relationship between two variables  Hypothesis  a testable prediction  often implied by a theory

The Scientific Method

 Replication  repeating the essence of a research study to see whether the basic finding generalizes to other participants and circumstances  usually with different participants in different situations  Replication is made possible by Operational Definitions

The Scientific Method  Operational Definition  a statement of procedures (operations) used to define research variables  Example-  intelligence may be operationally defined as what an intelligence test measures