Abstract
Much work has demonstrated that scene context guides visual search toward likely target spatial locations and facilitates target detection. When the location of the target violates observer expectations then search performance deteriorates. Here, we hypothesize that scene context contributes to search in another distinct manner: scene context guides search toward likely spatial scales of the target. When targets are mis-scaled relative to other objects in the scene they will be harder to find even if they are more salient in isolation. Methods: Eye-tracked participants (n = 60) searched for different cued target objects in 42 scenes (yes/no task; 21 target present and 21 target absent scenes) presented for 1.5 s. Seven trials contained a target consistent in scale with the scene and another seven trials contained a scene with the target that was inconsistent in scale (increased size) relative to the background objects in the scene. To isolate effects of target/scene scale inconsistency from target size, seven additional trials contained a control version of the scene, cropped and magnified so that the target was the same size as in the mis-scaled scenes but consistent in scale with the scene. Images for the various trial types were counterbalanced across observers and trial order was randomized. Results: Hit rate for the target decreased from 0.816 to 0.685 (p 0.001) when the target was mis-scaled relative to the scene. Hit rate in the control trials was 0.97 suggesting that it is not target size but inconsistency in scale with the scene which drives the detrimental effect on target detection. Eye movement analysis found very small differences (less than deg) in foveation of targets across scale consistent and inconsistent conditions. Conclusion: Our results strongly suggest that scene context not only guides search to likely possible target locations but also toward likely spatial scales.
Meeting abstract presented at VSS 2016