Chapter 9, Problem 6RE

Eyewitness Accuracy of Police Does stress affect the recall ability of police eyewitnesses? This issue was studied in an experiment that tested eyewitness memory a week after a nonstressful interrogation of a cooperative suspect and a stressful interrogation of an uncooperative and belligerent suspect. The numbers of details recalled a week after the incident were recorded, and the summary statistics are given below (based on data from “Eyewitness Memory of Police Trainees for Realistic Role Plays.” by Yuille et al., Journal of Applied Psychology. Vol. 79, No. 6). Use a 0.01 significance level to test the claim in the article that “stress decreases the amount recalled.”

$\text{Nonstress}:n=40,\bar{x}=53.3,s=11.6$

$\text{stress:}n=40,\bar{x}=45.3,s=13.2$