Abstract
Natural visual experience is seamless; we can quickly and effortlessly extract across stimulus categories, such as objects and scenes, while adapting to differences in physical input and task demands. For instance, when walking through the woods one can choose to inspect the richly textured bark of a tree, take a step back and perceive a single redwood, or step back further to take in the entire forest. Much work has focused on the cortically distinct representations of scenes, objects, and faces; naturalistic switches have been largely unstudied, despite that most of our waking hours are spent changing our gaze direction (panning) and distance from (zooming) various objects, people, scenes, and textures.
We created a novel stimulus set of 16-second "movies" (constructed by cropping 240 frames from a high-resolution image) that zoom and pan to gradually change from predominantly object to predominantly scene. By playing these movies backwards and forwards, we intend to characterize how dynamic inter-category transitions influence overt attention and categorization judgments while holding constant low-level visual features.
To determine the influence of one’s experience with a stimulus on its subsequent interpretation, we asked observers to judge whether the label ‘object’ or ‘scene’ best describes each movie along its time course. Each trial presented a movie twice: observers first viewed it freely, then were given semantic labels for judging the transition (e.g., ‘city to car’). They pressed a key to indicate when they first perceived the image to be predominantly ‘car’ as they viewed the movie again. Overall, both scene-to-object and object-to-scene iterations were reported as predominantly scene. Notably, we found an effect of anchoring on the first-presented stimulus: observers categorized the movie as an object about 3.12s longer if the movie began with an object. This suggests a marked effect of perceptual hysteresis for the object-scene category judgment.
Meeting abstract presented at VSS 2012