Pattern uncertainty and the discrimination of visual patterns

Abstract

Sixty Ss individually sorted eight decks of 50 cards each. A deck contained 25 cards each of two stimulus patterns. The patterns were drawn from different sets of five-dot patterns judged to be equivalent. The eight decks represented pairs of patterns drawn (a) from the same equivalence set, (b) from different equivalence sets of the same size, and (c) from different equivalence sets of different sizes. Sorting times were shown to increase with increasing size of equivalence set, and were shown to be greater for patterns drawn from within the same equivalence set than for patterns drawn from different equivalence sets. Ratings of pattern goodness were found to be useful predictors of sorting time only in their capacity to discriminate between equivalence sets of different sizes. The results were interpreted as supporting the importance of equivalence set membership in a discrimination task where the S logically does not have to consider stimuli other than the given criterion stimuli.