Purchase this article with an account.
Alex White, Sam Tatam, Daniel Linares, Alex Holcombe; Visuomotor compensation for variation in perceptual latency. Journal of Vision 2009;9(8):841. doi: 10.1167/9.8.841.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The less intense a stimulus is, the more time it takes the neural signal from the retina to reach visual cortex (Maunsell et al, 1999). Presumably because of this variation in latency, a dim moving object appears to lag behind where it would appear if it were bright (Hess, 1904). To investigate whether this flaw in perception afflicts our ability to interact with moving objects, we asked subjects to press a button at the moment a rotating bar became aligned with a stationary reference (no feedback was provided). Over a 15-fold photopic range of luminance, they did not respond later when the moving bar was dimmer. However, the results of two perceptual localization tasks with similar stimuli indicated that the bar appeared further behind when it was dimmer, relative to a reference bar that was either moving (the Hess effect) or flashed (the flash-lag effect). This suggests that the visuomotor system compensates for changes in visual latency due to luminance variation, despite uncorrected lags in conscious perception. A further experiment suggested that the divergence of perceptual latencies and motor timing is not restricted to moving stimuli: when subjects synchronized button presses with a periodically flashing bar, the effect of luminance on their errors was smaller than the effect on perceptual latency as measured by the Hess effect. However, this compensation appears to function only within a daytime range of luminance. When the tasks with moving stimuli were conducted again but in a lower, mesopic range of luminance, the synchronization responses were significantly delayed by decreasing luminance to an extent nearly in agreement with the perceived location of the moving bar. One possible explanation is that the adult visuomotor system has learned through life experience to trigger timed actions earlier when visual signals are weak.
This PDF is available to Subscribers Only