CONDITIONED AFTER‐IMAGES. II

Abstract

Two experiments are described in which subjects report conditioned visual after‐images. The first is concerned with visual after‐images evoked in response to an auditory stimulus and the effects of manipulating the CS‐US ‘dynamic stereotype’. Certain aspects of the data are compared with data obtained in similar experiments in the U.S.S.R. by Bzhalava and the Popovs with which there is seen to be a considerable measure of agreement. The results obtained suggest that a light flash (the primary source of unconditioned after‐images) may, through repetition, come to acquire the status of a conditioned stimulus. The second experiment is an investigation of this latter phenomenon and evidence is presented which may be seen as supporting the view that after‐images may be conditioned to a repeated visual stimulus. Other possible interpretations of the observed results are discussed but these are rejected in favour of the conditioning hypothesis.