Scientific methods in psychology Why we have confidence in the principles of contemporary psychology

It all starts with: A problem, A problem, Or a question, or Or a question, or Maybe just an observation. Maybe just an observation. That leads to a….. That leads to a…..

theory A comprehensive explanation of observable events A comprehensive explanation of observable events It should be: It should be: 1) willing to take chances - falsifiable, 1) willing to take chances - falsifiable, 2) empirical – based upon observations, experiments, or measurement and 2) empirical – based upon observations, experiments, or measurement and 3) as simple as possible 3) as simple as possible

parsimony Science prefers simplicity Science prefers simplicity Science is very reluctant to accept theories that contradict firmly established principles Science is very reluctant to accept theories that contradict firmly established principles UFO’s, living fossils UFO’s, living fossils But we must keep But we must keep an open mind

esp Acquiring information without the use of sense organs and without receiving any form of physical energy Acquiring information without the use of sense organs and without receiving any form of physical energy Widely accepted, but valid? Widely accepted, but valid? Throw away physics?!? Throw away physics?!? Suspicious “proof” Suspicious “proof” No one has met Randi’s No one has met Randi’schallenge

The process of gathering and evaluating evidence Universally accepted format Universally accepted format Hypothesis - a testable prediction Hypothesis - a testable prediction Will exposure to violent video cause children to be more aggressive? Will exposure to violent video cause children to be more aggressive? Will phonics training help young children read better? Will phonics training help young children read better? Will watching Sportscenter with your boyfriend lead him to watch the Notebook with you? Will watching Sportscenter with your boyfriend lead him to watch the Notebook with you?

And then … The phenomena of interest is defined precisely, or operationally, and then investigated in some manner, such as by: The phenomena of interest is defined precisely, or operationally, and then investigated in some manner, such as by: Observation Observation Interviews Interviews Research Research Correlations Correlations

peer review & replication peer review & replication If other researchers follow your method to investigate your hypothesis, will they get the same results? If other researchers follow your method to investigate your hypothesis, will they get the same results? If they do, the hypothesis has been replicated – confirmed, leading to more confidence in it. If they do, the hypothesis has been replicated – confirmed, leading to more confidence in it. If they don’t, confidence in the hypothesis is diminished. If they don’t, confidence in the hypothesis is diminished.