Search

The aim of this investigation was to compare the effects of three different degrees of expectancy on the perception of relative length. It was assumed that expectancy would be (a) maximal when erroneous information about the relative length of two equal lines was deduced fallaciously by the subjects, (b) intermediate when the same information was presented by the experimenter, and (c) zero when no such information was presented. It was predicted that the subsequent perception of length would vary in accordance with the degree of expectancy induced, i.e. (a) > (b) > (c). The prediction was confirmed at a high confidence level for the frequency of perceptual judgements, but the amount of perceptual distortion did not differ significantly although the means were in the predicted order. The results are discussed in relation to theories of perception and cognition.