Professor Grune Is Conducting an Experiment on Perceptions of the Credibility

Multiple Choice

Professor Grune is conducting an experiment on perceptions of the credibility of eyewitness testimony. While the study was in progress, a case of mistaken identity received wide publicity: A person who was on death row was exonerated because the key witness had mistakenly identified him as the murderer. Professor Grune found that his participants were less willing to believe an eyewitness after the case was publicized. His research was hampered by a ________ confound.

A) maturation
B) history
C) testing
D) measurement