Abstract
People can extract the gist of complex scenes (e.g. natural or urban) so rapidly that it has been proposed that scene categories are extracted in the initial, feed-forward sweep of information processing. If so, initial gist processing might resist object substitution masking (OSM), which is thought to interfere with the reentrant, feedback processing considered to be needed for conscious experience of stimuli. If a scene is blocked from awareness by OSM, is its categorical status still computed? Seventeen observers saw displays of three textures and one target that could be either a scene or a texture. The target was surrounded by four small, identical scenes (the mask). OSM was produced when mask offset was delayed relative to target offset. Observers' primary task was speeded discrimination of the category of the mask stimuli (urban/natural). The secondary task was identifying the target as scene or texture. Secondary task performance was 67% correct if mask offset was simultaneous with target offset (no OSM) but only 54% in the delayed offset, OSM conditions. The secondary task significantly influenced the primary. When the target was reported, RTs for mask identity were faster when target and mask were compatible (1095 ms) than when they were incompatible (1158 ms). In the OSM condition, with the target not seen, an effect remained but it was reversed. Compatible was slower (1164 ms) than incompatible (1110 ms). Either way, this shows an influence of the secondary task target on the primary response to the mask's identity. The effect is of most interest in the OSM condition when the identity of the target does not reach awareness. The gist of unseen scenes effects the categorization of other scenes. This gives credence to the hypothesis that feed-forward, non-selective processes are adequate to determine at least some aspects of scene gist.
NIH/NEI 1F32EY019819-01 to KKE, NIH EY017001 and ONR MURI N000141010278 to JM.