Influence of Knowledge of Results on Performance in a Monitoring Task

Abstract

Vigilance performance was tested in six independent groups with a modified version of the Mackworth Clock Test. The groups constituted a 3 × 2 design with (a) no knowledge of results, observer-presented knowledge of results, and machine-presented knowledge of results as one dimension, and (b) physical presence or absence of an observer in the test cubicle as the other variable. All groups were retested without knowledge of results one and seven days after the initial test. On the initial test day, groups with no knowledge of results and machine-presented knowledge of results showed the typical decrement function throughout the session. In contrast, Ss receiving verbal knowledge of results from the experimenter showed less decrement and a significantly higher over-all performance. The superiority of the groups receiving the verbal report persisted on the two subsequent test days despite the fact that all extrinsic knowledge of results was withdrawn on these tests. Observer-presented knowledge facilitated performance regardless of the physical presence or absence of the observer in the test cubicle.