Concept Identification as a Function of Proportion of Positive Instances and Concept Size

Résumé du livre

The present study investigated the effects of four proportions of positive instances (1/8, 2/8, 3/8, and 4/8) and three levels of concept size (one, three, and five nonredundant relevant binary stimulus dimensions) in a conjunctive concept identification task. Visual stimuli were presented to 192 university undergraduate Ss, each serving once in a problem consisting of 96 instances. A two-choice response system was used with 100% informative feedback. The primary measure of performance employed was errors per block of 16 instances. The results showed that mean total errors increased as the proportion of positive instances increased in the range 1/8 to 3/8, but that the 4/8 condition led to fewer errors than any of the other three. It was also found that errors increased as a negatively accelerated function of size. Proportion of positive instances did not interact with size. The results, interpreted in relation to other research, suggest that Ss utilized differential category frequencies as a basis for responding to reduce errors when this was possible. The results have serious implications for concept identification research, and for an understanding of the process of concept learning.