Feature Frequency and Negative Instances in Concept Learning

Abstract

In conjunctive feature identification tasks, sequences of all positive instances are favored over mixed sequences of positive and negative instances in laboratory tasks, but in mathematical conjunctive feature identification tasks, mixed sequences are favored over all positive instances. The subjects were 100 adolescents randomly assigned to one of four treatments formed by crossing sequence condition (positive or positive/negative) with relative frequency of features of irrelevant dimensions (equal or unequal). Results support the classical favoring of positive over positive/negative for equal frequency of irrelevant features (1:1) but positive/negative over positive for unequal frequency of irrelevant features (9:1) (p < .05). Feature frequency of irrelevant dimensions is shown to be a critical factor in the effects found for negative instances. Implications for educational practice are discussed.