Establish a relationship between stress hormones and the verbal recall of information.
Research method
Double-blind, true experiment.
Participants
Students and staff of Washington University Medical Centre.
Group 1: High level of cortisol
Participants were given 160mg of cortisol (equal to a majorstress event).
Group 2: Low level of cortisol
Participants were given 40mg of cortisol (equal to the undergoing of a minor surgical event).
Control group: placebo
Placebo tablets.
Procedure
All participants were asked to listen to and recall a prose paragraph. Each day for four days they were given a different piece of prose with the same level of difficulty. They were tested three times.
Controlling the experiment
All participants were first tested before taking any cortisol. The finding was that there was no significant difference between groups. This is an important control to make sure that at baseline, individual differences will not be a confounding variable for the study.
Results
Those with high level of cortisol showed impaired performance on memory tasks. Hence, researchers identified a clear link between levels of cortisol and memory performance.
Strengths
Cause-effect established, high internal validity, baseline and clinical interviews held prior.
Limitations
Low ecological validity, slightly unethical due to stress tablets, participants were not in the lab the entirety of the four days which allowed extraneous variables.
