Abstract
Selection of behaviourally relevant locations and objects requires guided search and selective attention. Most search experiments involve static displays, with a pre-specified target. However, such studies do not reflect the dynamic environments experienced in real-world situations. Further, in the Motion Silencing Effect (MSE), the ability to detect feature change is dramatically disrupted by the motion of the items in the display. This study investigates the MSE in static and dynamic displays that consist of 16 Gabor patches (contrast = 1, 5 cycles per degree) arranged in an annulus (11.2° visual angle eccentricity) around fixation. The patches changed local orientation, and the display was shown for 2,000 ms at various global rotational velocities (0°/sec, 24°/sec, 48°/sec, 72°/sec, 96°/sec). Eight observers completed 2,160 trials each, over three experimental sessions. Throughout the experiment, participants made binary judgements after each display, indicating whether they perceived a local orientation change in the Gabor patches. The results show a clear decrease in local orientation change detection as global velocity increased. We found no evidence that the static condition was qualitatively different from the other conditions that involved global rotation. The data was well fit by a Weibull psychometric function, and the mean 75% rotational velocity threshold across participants was 83.9° per second, 95% CI [71.9, 95.8]. The results demonstrate that local orientation change detection was less accurate with increasing global motion of the display, in line with the MSE. These results are an important first step in establishing that motion can silence orientation change detection and suggest why changes in real-world situations, which involve moving objects, may be easily missed. Further investigations into the role of motion silencing in dynamic visual search is needed to more fully understand how motion silencing might interact with other key parameters such as attention.