BACKWARD-MASKING OF WORDS AND FACES - EVIDENCE FOR DIFFERENT PROCESSING SPEEDS IN THE HEMISPHERES

Two tachistoscopic experiments with a lateralized presentation of func tion words and faces were carried out to investigate the influence of temporal factors and type of masking on visual field asymmetries. Accu racy, represented by signal detection measures (d' and beta), was calc ulated separately for the two visual fields, for various interstimulus intervals, and for noise and pattern masking. In both experiments, d' increased with prolonged temporal delay between target and mask. In t he lexical decision task, visual field interacted with mask type confi rming that only in the pattern mask condition did an advantage of the right visual field emerge. In the facial decision task, however, visua l field interacted with interstimulus interval, confirming that, in th e left visual field, the facial information escaped the masking effect earlier than in the right visual field. In the facial task, there was a higher response criterion (beta) in the left visual field. By apply ing different types of masks, visual processing of lexical stimuli can be disrupted at distinct stages where perceptual asymmetries are pres ent to a varying extent. The results of both experiments suggest that words and faces are differentially affected by masking procedures. (C) 1997 Elsevier Science Ltd.