ATTENTIONAL CAPTURE BY ABRUPT ONSETS - NEW PERCEPTUAL OBJECTS OR VISUAL MASKING

The authors have shown that an object appearing abruptly in a previous ly blank location is efficiently detected in visual search when it is embedded in an array of objects without abrupt onset (termed no-onset stimuli). In these experiments, no-onset stimuli appeared well before the onset stimulus but were camouflaged by additional line segments re ndering the stimuli unidentifiable. B. S. Gibson (1996) claims that th e availability of the no-onset stimuli was delayed relative to that of the abrupt onset stimulus because of forward masking. The authors sho w that forward masking is unlikely to be a significant factor in their experiments, and 3 new experiments are reported that undermine Gibson 's masking account. Observed differences in the efficiency with which onset and no-onset stimuli are processed in visual search are due to a ttentional capture by new perceptual objects and to a relatively slugg ish process of updating existing object representations.