Abstract
The double-drift stimulus — a drifting gabor with orthogonal internal motion — produces a dramatic shift of its perceived location but no error in saccades that target it (Lisi & Cavanagh, 2015). In the current study, we used this stimulus within the context of a multiple object tracking task in order to test whether the attention involved in tracking is more like the form of attention used to execute saccades or like that which supports perception. Observers (n=7) were asked to track 1-4 targets among 4-7 distractors (with all trials containing 8 total identical moving objects); all targets and distractors were double-drift stimuli. If tracking engages a form of spatial attention that is related to saccades, we expect no effect on tracking performance compared to a control condition (where the gabors had no internal motion). Conversely, if tracking is based on a form of spatial attention that is independent of the saccade system we expect a loss of performance since targets and distractors would have large illusory shifts in location and direction. Results indicate an overall impairment for tracking objects with internal motion [F(1,1882)=11.5, p< .01], but pairwise comparisons for each level of tracking load show no significant differences between these conditions; tracking performance was essentially unaffected by the internal motion. This indicates that the tracking process can operate independently of the forms of attention that support perception, suggesting a dissociation between neural systems for perception and those for attention.
Meeting abstract presented at VSS 2016