Response Coding in Recall of Colours by Monkeys

Abstract

Two monkeys learned a recall task with colours as the samples and spatial discriminanda at the retention test. The relationship between the sample colours and the retention test discriminanda was such that it was possible to distinguish between errors that were related to the visual similarity of the sample colours and those that were related to the similarity of the recall responses. When errors were induced by lengthening the delay between sample and retention test, they were related to the similarity of the recall responses. But in a comparable recognition memory task with colours, performance was related to the visual similarity of the colours. These results imply that the monkeys recognised the colours directly from a visual trace but recalled them indirectly from a response-coded trace.