Locus of Control and Alcohol Placebo Effects on Performance in a Driving Simulator

Performance in a driving simulator was evaluated as a function of locus of control, perceived alcohol ingestion (no alcohol versus a no-alcohol placebo), and sex. Using a pretest-posttest design, an analysis of covariance was performed using the pretest performance on a driving simulator as the covariate. There were 10 men and 10 women in each of four groups. As predicted, the external-scoring placebo subjects made more posttest errors than did the internal-scoring placebo group or either of the no-alcohol control groups. This indicated that the external-scoring placebo subjects were more affected by what they expected to happen than their actual physiological state warranted. A difference was also found in which external-scoring women made more errors than did any other group. This was an unexpected finding which, being inconsistent with previous findings involving sex, warrants further research.