Size Constancy and Cue Responsiveness in Psychosis

An experiment is reported designed to re‐assess size constancy behaviour and some of its co‐relatives in psychotic and non‐psychotic subjects. The predictive basis of reduced size constancy for schizophrenic and non‐schizophrenic psychotic patients was found in the clinical evidence characterizing these conditions and in Piaget's genetic theories of cognitive development. It was postulated that there would be no significant difference in size constancy between different psychotic groups or between different non‐psychotic groups, but that the psychotic groups would show significantly reduced size constancy compared with the non‐psychotic sample. It was further postulated that low size constancy would be positively related to reduced cue responsiveness operationally defined in several different ways. Size constancy and cue responsiveness in relation to familiar and non‐familiar objects are assessed. The results are taken to provide a considerable degree of support for the hypotheses, and are explained in terms of peripheral as well as central mechanisms. The findings do not support previous evidence suggesting a causal relationship between low size constancy and under‐estimation of distance.