Abstract
Theories of visual attention suggest two opposed control mechanisms: On the one hand there is intentional allocation of attention to specific objects or locations, or on the other hand involuntary attentional selection by salient stimulus properties. These mechanisms may also be depth-sensitive. Accordingly, attention focused on a specific depth plane would be affected by salient stimuli presented in other (unattended) depth planes. The present study investigated this issue using the additional singleton paradigm. In a first experiment, participants searched for a target displaced in depth (i.e. shifted to a closer or farther depth position). At the same time an additional but irrelevant singleton (distractor) was presented within the same or a different depth plane. This distractor could also vary in terms of color (same or different as the target). Analysis of reaction times revealed that participants responded slower in case the distractor was located within the same depth plane as the target. The color of the distractor did not further modulate reactions times. A second experiment tested whether the relative depth positions ("near" vs. "far") of target and distractor are behaviorally relevant. As previously observed, reaction times were faster when target and distractor were displayed in different depth planes. Moreover, it was evident that participants identified the target faster if it was presented in the "near" depth position, although participants were informed in which depth plane the target will appear. Taken together both experiments suggest that stereoscopic depth information can be employed to focus attention on a specific depth plane. This mechanism, however, may not be prone to distraction from other depth planes. In particular, targets in "near" position are detected faster than those displayed in "far" position, which might indicate attentional capture from unattended depth planes.
Meeting abstract presented at VSS 2018