Attentional Modulation in Perception of Visual Motion Events

Abstract

Identical visual targets moving across each other with equal and constant speed can be perceived either to bounce off or to stream through each other. This bistable motion perception has been studied mostly in the context of motion integration. Since the perception of most ambiguous motion is affected by attention, there is the possibility of attentional modulation occurring in this case as well. We investigated whether distraction of attention from the moving targets would alter the relative frequency of each percept. During the observation of the streaming/bouncing motion event in the peripheral visual field, visual attention was disrupted by an abrupt presentation of a visual distractor at various timings and locations (experiment 1; exogenous distraction of attention) or by the demand of an additional discrimination task (experiments 2 and 3; endogenous distraction of attention). Both types of distractions of attention increased the frequency of the bouncing percept and decreased that of the streaming percept. These results suggest that attention may facilitate the perception of object motion as continuing in the same direction as in the past.

Effects of the orientation of moving objects on the perception of streaming/bouncing motion displays

“…First, the shift of visual attention with the transient flash could generally increase the bias toward bouncing, which is consistent with the results of previous studies (Burns & Zanker, 2000;Watanabe & Shimojo, 1998). Second, when the transient flash was presented, the perception of bouncing did not increase when the Gabors were aligned with their motion path (0º and 15º).…”

“…In previous studies, a transient auditory signal at co- Time incidence biased the perception toward bouncing (Sekuler et al, 1997;Watanabe & Shimojo, 2001a, 2001b, as did distraction of visual attention (Burns & Zanker, 2000;Watanabe & Shimojo, 1998). However, in these previous studies, since a uniform geometric object was used as the moving object, it was unclear how the motion integration mechanism interacted with the modulation of attention.…”

“…Therefore, it was unclear whether distraction of unimodal attention by the presentation of a transient flash would be as strong as that by presentation of a transient tone in Experiment 1. In previous studies, Watanabe and Shimojo (1998) showed that the sudden onset of distractors can distract visual attention away from a moving object, resulting in a significant increase in the perception of bouncing (see also Burns & Zanker, 2000). In the following experiments, we investigated the potential effects of distracting visual attention away from the object during perception of streaming/bouncing where the Gabor orientation was modulated as in Experiment 1.…”

“…Using a task in which observers detected motion direction in a random-dot kinematogram, Isaak and Fawcett (1997) reported the impairment of local motion integration when visual attention was distracted from the target motion. On the basis of these findings, Watanabe and Shimojo (1998) …”

The persistence of object file representations

“…In particular, many well-known visual phenomena also unfold over the course of several seconds, and we can thus ask about the roles that object files play in such situations. To take a single example, many researchers have explored object persistence using only simple perceptual reports on ambiguous dynamic displays, such as "bouncing versus streaming" (e.g., Bertenthal, Banton, & Bradbury, 1993;Sekuler & Sekuler, 1999;Watanabe & Shimojo, 1998). In such displays, two objects move on opposite diagonals of a square (meeting in the center before continuing their motion) and can be seen as either streaming past or bouncing off each other.…”