Accuracy of recognition with alternatives before and after the stimulus.

Abstract

Sixty Ss, divided into three groups of 20 each, were shown tachistoscopically presented pictures at various exposure intervals and asked to identify them. The control group had no alternatives presented to it, whereas the two experimental groups each had a set of four alternatives specified for each stimulus. One experimental group had the alternatives presented before the stimulus exposure and the other group following the exposure. The alternatives were of two types: (a) SA, or very similar alternatives all suggesting perceptually similar objects, and (b) DA, or discrete alternatives all suggesting perceptually different objects. The results and the interpretations made were as follows: 1. The two groups with alternatives were superior to the control group without alternatives in accuracy of recognition even when allowance was made for guessing. 2. Alternatives before and after the stimulus facilitated recognition to an equal extent. 3. The facilitative effect of DA was consistently greater than that of the SA at all exposure times, but there was no evidence of an interaction effect between the type of alternative and when it was presented in relation to the stimulus exposure. 4. These results tend to rule out the hypothesis that the facilitative effect of alternatives results from an actual modification of perception and support the hypothesis that they operate either on the memory trace or response aspects of the recognition process.