Discrimination of Word-Like Compound Visual Stimuli by Monkeys

In Experiment I, two monkeys solved a successive visual discrimination in which the four positive stimuli were the visual arrays RIM, LID, RAD and LAM while the four negative stimuli were RID, LIM, RAM and LAD. In Experiment II the same monkeys first learned a discrimination where the positive stimuli were pairs of letters (e.g. OB and AK) while the negative stimulus was the letter I; in a subsequent generalization test with all four possible pairings of the stimulus elements that had been positive during training (i.e. with OB, AK, OK and AB) the monkeys responded more strongly to the pairs that had been present in initial training. These results were discussed in relation to the theoretical analysis of configurational cues in animal discrimination learning and to the mechanism underlying visual discrimination of words by people.

Use of Criterial Measures in Animal Discrimination Learning Experiments

Findings from 2 experiments are described in which rats were overtrained on black/white and conditional discriminations. on the former, performance improved up to criterion and thereafter was maintained at a high level. on the latter, more difficult task, behaviour was less consistent and performance deteriorated with overtraining. A relation between elimination of position responses and task difficulty is suggested, and implications for the use of learning criteria are discussed.