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Effect of Altered Outcome Expectancies Stemming From Placebo and Feedback Treatments on the Validity of the Guilty Knowledge Technique

NCJ Number
Journal of Applied Psychology Volume: 67 Issue: 4 Dated: (1982) Pages: 391-400
Date Published
10 pages
This study attempted to alter subjects' degree of certainty that their deceptive responses on a polygraph test would be correctly detected by manipulating placebo and feedback treatments.
Subjects were 270 undergraduate college students. Each subject committed a mock murder, after which the investigator administered a series of five lie detector tests to ascertain the facts involved in the simulated murder. Prior to testing, an equal number of male and female subjects were randomly assigned to one of nine treatment groups. The nine groups consisted of the different treatment combinations produced by pairing one of three placebo conditions (pass, control, fail) with one of the three feedback conditions (pass, control, fail). Although highly significant sex and feedback effects on outcome expectancies were found, there were no significant main or interaction effects produced by sex, feedback, or placebo conditions with respect to detection efficiency, as measured by a standard guilty knowledge scoring procedure. Study data, 2 reference notes, and 25 references are provided. (Author abstract modified)

Date Published: January 1, 1982