Backward masking spatial frequency effects among hypothetically schizotypal individuals.

The present investigation relied upon a neurophysiological explanation of visual masking and compared the backward masking susceptibility of hypothetical schizotypal individuals to that of controls. In order to assess the relative contributions of the visual system's transient and sustained channels to the backward masking deficit characteristic of the schizophrenia spectrum, performance within low spatial frequency (LSF) and high spatial frequency (HSF) masking conditions was compared. Because this design was intended to test the hypothesis that a transient channel abnormality underlies the spectrum masking deficit, only the transient facilitating, LSF masking condition was expected to produce group differences. Although the two masking conditions were equivalent in their stimulus energies, as predicted, the at-risk subjects evidenced an LSF masking deficit, but did not differ from controls in the sustained facilitating, HSF masking condition. These results suggest that multichannel neurophysiological models of masking may help to direct research designed to gain an increased understanding of the specific nature of the spectrum masking deficit.