Abstract
Prior research has established that scene gist (semantic category) is acquired within a single fixation. The present study used a new paradigm to investigate how quickly gist becomes available, and whether color is important in its activation. Previous studies have shown that when a scene is presented quickly, there is a natural bias to affirm having seen a semantically consistent target object in that scene and to deny having seen an inconsistent object (Hollingworth & Henderson, 1999). The Contextual Bias paradigm tracks the timing of semantic gist activation by measuring the onset of this response bias. If a scene presented for a given duration is perceived and processed to the level of gist, then subjects should be more likely to respond “yes” to consistent and “no” to inconsistent targets. If, however, the scene is not perceived or processed to the level of gist, then participants should respond “yes” to both target types in equal proportions. Experiments 1–3 investigated how quickly scene gist becomes available. Results suggested that gist is available 42 ms after scene onset. Experiments 4–6 investigated the relative contribution of color and structure for very short scene durations by manipulating the color (color vs. monochrome) and sharpness (sharp vs. blurred) of the scenes. Results showed that color influences gist activation later (80 ms), and only when structure was degraded (blurred). Thus, color may play a role in rapid scene gist activation, but only when the scene's structural information is relatively more difficult to extract. Whether color influences the activation of semantic information by providing supplementary structural information (separating equiluminant regions) or by providing unique scene categorization cues is the subject of current investigations.
This work was supported by the National Science Foundation (BCS-0094433 and ECS-9873531), NSF IGERT Program (DGE0114378), and Army Research Office (W911NF-04-1-0078).