CAPTURING VISUAL-ATTENTION AND THE CURVE TRACING OPERATION

The hypothesis that orienting visual attention is an important component of visual curve tracing was investigated. Ss examined a visual display and decided as quickly as possible whether 2 dots were on the same or different curves. The rate of tracing was determined by measuring the effects of curve distance on response time. Attention was directed to a curve by momentarily presenting it at a higher luminance. Directing attention to a curve that had two dots on it resulted in faster tracing rates with large benefits in overall response time. Directing attention to a distractor curve resulted in slower tracing rates and sizable costs in overall response times. Two alternative nonattentional explanations-eye movements and visible persistence - were examined and rejected. The role of attention in curve tracing is discussed in terms of the selective nature of curve tracing.