The role of uncertainty in the systematic spatial mislocalization of moving objects.

Abstract

It only makes sense to talk about the position of a moving object if one specifies the time at which its position is of interest. The authors here show that when a flash or tone specifies the moment of interest, subjects estimate the moving object to be closer to where it passes the fixation point and further in its direction of motion than it really is. The authors propose that these biases arise from a combination of a large temporal uncertainty, a temporal asymmetry related to sampling the moving object's position, and a bias toward believing that one is looking at what one sees.

Effects of texture and shape on perceived time to passage: Knowing “what” influences judging “when”

“…The SD values were similar for all the conditions (0.12 sec) and consistent with values from previous studies (e.g., Gray & Regan, 2000;Regan & Hamstra, 1993). They are not much greater than values for synchronizing a flash with a beep (Brenner, van Beers, Rotman, & Smeets, 2006), so subjects appear to be able to do the extrapolation quite well. Adding texture did not improve the sensitivity of TTP judgments.…”

“…Thus, the fact that we found no improvement in judgments of TTP when we added texture does not necessarily mean that only changes in the outline are relevant. Perhaps the resolution with which the rate of expansion can be determined is not critical for performance on this task (e.g., it may be negligible in comparison with the poor temporal resolution; Brenner at al., 2006), so that providing more expanding structures does not improve precision.…”

Perisaccadic Compression Correlates with Saccadic Peak Velocity: Differential Association of Eye Movement Dynamics with Perceptual Mislocalization Patterns

“…Simulating the consequences of a saccadic eye movement by fast motion of the retinal image during fixation yields a shift but no compression of apparent positions, which was taken as evidence that only the latter may be mediated by a corollary discharge associated with the oculomotor command . However, a complete dissociation between real and simulated saccade conditions has been challenged by recent studies that found more perceptual compression around the apparent motion of visual stimuli under steady visual fixation than previously expected (Brenner et al, 2006;Ostendorf et al, 2006;Shim and Cavanagh, 2006;Watanabe and Yokoi, 2006). The latter finding may suggest that extraretinal signals associated with attention shifts or preparatory oculomotor activity contribute to perisaccadic perceptual compression.…”

“…Indeed, the majority of collicular neurons projecting back to thalamic nuclei were classified as visuomotor neurons (Sommer and Wurtz, 2002), a class of neurons shown to be active during covert shift of visual attention as well (Ignashchenkova et al, 2004). The concept of the putative underlying extraretinal signal being commensurate with an attentional top-down signal (Awater and Lappe, 2006) could provide a unifying approach for similar mislocalization patterns around saccades and passive motion of the retinal image (Brenner et al, 2006;Ostendorf et al, 2006;Shim and Cavanagh, 2006;Watanabe and Yokoi, 2006). Here, the reported relationship between saccadic peak velocity and perisaccadic perceptual compression could serve as a powerful tool to further disentangle the respective contributions of visual, attentional, and saccaderelated extraretinal signals to perisaccadic mislocalization: an examination of perceptual compression in patients with pathologically slow saccades may help to further clarify the respective contributions of visual and extraretinal signals to perisaccadic localization and the cerebral mechanisms of visual stability across saccades.…”

“…Higher retinal speed may not only lead to a less accurate alignment of a briefly presented stimulus with stable visual references and/or extraretinal signals but may also increase the spatiotemporal uncertainty of its representation. A less reliable representation may then be biased more strongly toward salient references (e.g., the saccade target), resulting in a stronger compression of apparent positions with higher retinal image speed (Brenner et al, 2006;Ostendorf et al, 2006). Following this hypothesis, not only the systematic bias but also the variability of perceptual localization should vary with saccadic peak velocity, which is not supported by our dataset: individual localization variability just after saccade onset (i.e., at the moment of maximal compression) did not correlate with mean saccadic peak velocity (supplemental Fig.…”