Psychology as a Science Chapter 1

The Scientific Attitude Curiosity, skepticism, humility Scientific attitude Examine assumptions Discerns hidden values Evaluates evidence Assesses conclusions

The Scientific Attitude Limits of intuition & common sense Hindsight bias – I knew it all along phenom. 9/11 What would you consider the climate of Antarctica? Overconfidence Convince ourselves we were almost right What is the point farthest east in the US?

The Scientific Method Theories – organize and predict Hypothesis – TESTABLE prediction Operational definition – definitions and measures for a specific study Strong hypotheses should be able to be replicated Cycle of theoretical research (page 25, fig. 1.1)

Descriptive methods Case Study Survey Naturalistic Observation Wording effects Random sample Represents population False consensus Naturalistic Observation

Correlation Studies Correlation coefficient – statistical number that describes the strength of a relationship between two variables Strongest correlations are 1 & -1 Means that one strongly predicts the behavior of the other Use scatter plots and line of best fit to determine the strength of a correlation Correlations of >.5 or <-.5 are consider at least moderately strong We will talk about statistical significance later

Correlation Studies Correlation and causation No matter how strong a correlation is, it doesn’t mean one variable causes the other!!!!! Third factors can often be involved and muddy the ability to show causation Causation arrow could point both ways Cannot be used as proof!?

Correlation Studies Illusory correlations Illustrations of believed relationships lead to unscientific conclusions Need correlations based in data (math) not examples/case studies We naturally look for patterns as human beings

Experiments Experiment – investigator changes one or more variable (independent variable) to observe the effect on some behavior or mental process (dependent variable) Seeks to control other important factors Random sample Sample size Gives cause and effect if proper control of extraneous variables

Evaluating therapies Experimental condition – people receive the treatment or one version of the independent variable Control condition – closest approximation of “normal” conditions Comparison with experimental condition Contrasting in independent variable with EC

Evaluating therapies Double-blind procedure Random assignment Placing subjects into EC or CC without subject or experimenter knowing Controls placebo effect Random assignment Making sure that EC and CC are fundamentally the same “Average” subject in EC should match average of CC Larger sample gives a better chance of good grouping

Dependent vs. Independent variable Independent variable – variable that experimenters change from EC to CC This is the variable that is controlled/changed on purpose Dependent variable – this is a measurable difference between a factor in the EC and CC because of the change in the independent variable How it is measured is the same in both conditions Difference should be due to change in variable from one condition to the other

Measures of Central Tendency Mean = Average Add up each score (DV) and divide by the total number of scores Ex. 75, 80, 90, 80, 85, 60 470 ÷ 6 ≈ 78.3 Median = the middle score 75, 80, 90, 80, 85, 60 Median is 80 (if even number of scores (ex. 6) then mean of middle two) Mode = most often Which score is repeated the most? 80 is the mode 60, 75, 80, 80, 85, 90

Measures of Variation Data is better when it is clumped together Range The more spread the worse the correlation Range Largest – smallest = range e.g. 90-60 = 30 Standard Deviation How far from the middle is “normal” Two standard deviations is OK Bell curve Outside two deviations = outlier (weird) SD2 SD1

What do I Know Now? Reliable – can I apply my finding to everyone Representative sample Low-variation in scores/observations Large sample size Significant – how confident am I in the results If: Averages are reliable (see above) & The difference between the EC & CC averages is large Then the finding is significant Large is relative to the scores

Extra Stuff Do experiments work? Can result be generalized? What are ethics in research? Ethical standards Informed consent Freedom from harm Debriefing Justified use of deception Animal research Human research Values in psychology.