The Briefest of Glances:The Time Course of Natural Scene Understanding

摘要

What information is available from a brief glance at a novel scene? Although previous efforts to an_swer this question have focused on scene categorization or object detection, real-world scenes contain a wealth of information whose perceptual availability has yet to be explored. We compared image exposure thresholds in several tasks involving basic-level categorization or glo_bal-property classification. All thresholds were remark_ably short: Observers achieved 75%-correct performance with presentations ranging from 19 to 67 ms, reaching maximum performance at about 100 ms. Global property categorization was performed with significantly less pre_sentation time than basic-level categorization, which sug_gests that there exists a time during early visual processing when a scene may be classified as, for example, a large space or navigable, but not yet as a mountain or lake. Comparing the relative availability of visual informa_tion reveals bottlenecks in the accumulation of meaning. Understanding these bottlenecks provides critical insight into the computations underlying rapid visual under_standing.