Categorization and Identification of Simultaneous Targets (Categorisatie en Identificatie Van Simultaan Aangeboden Targets)
Abstract
Studies on visual attention are concerned with human limits in identifying simultaneously presented stimuli. Several studies have shown that the time to detect whether a single target categorically different from non- targets is present or not, is relatively independent of the number of non- targets in the display. Invariance of performance with display size is taken as evidence in favor of late-selection theories claiming unlimited-capacity, spatially parallel processing of all items in the display. As an extension of previous studies, in the present study two categorically different targets were presented simultaneously among a variable number of non-target. Subjects were shown brief displays of two target letters among either 2, 4 or 6 non-target digits. Subjects responded 'same' when the two letters were identical and 'different' otherwise. Since the 'same-different' response reflects the combined outcome of the simultaneous targets, late-selection theory predicts that the time to match the target letters is independent of the number of non-target digits. Alternatively, early-selection theory predicts a linear increase of reaction time with display size since the presence of more than one target disrupts parallel pre-attentive processing, leading to a serial search through all items in the display. The results provide evidence for the early-selection view since reaction time increased linearly with the number of categorically different non-targets. Netherlands.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 19, 1989
- Accession Number
- ADA218085
Entities
People
- E. Agterhuis