Daniel Linares

Where is the moving object now? Judgmentsof instantaneous position show poortemporal precision ( SD = 70 ms)

Humans can precisely judge relative location between two objects moving with the same speed and direction, as numerous studies have shown. However, the precision for localizing a single moving object relative to stationary references remains a neglected topic. Here, subjects reported the perceived location of a moving object at the time of a cue. The variability of the reported positions increased steeply with the speed of the object, such that the distribution of responses corresponds to the distance that the object traveled in 70 ms. This surprisingly large temporal imprecision depends little on the characteristics of the trajectory of the moving object or of the cue that indicates when to judge the position. We propose that the imprecision reflects a difficulty in identifying which position of the moving object occurs at the same time as the cue. This high-level process may involve the same low temporal resolution binding mechanism that, in other situations, pairs simultaneous features such as color and motion.

Visuomotor timing compensates for changes in perceptual latency

Summary The dimmer a stimulus is, the more time it takes the neural signal from the retina to reach visual cortex [1]. Presumably because of this variation in latency, a dim moving object appears to lag behind where it would appear if it were bright [2,3]. 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: over a 15-fold range of luminance, they did not respond later when the moving bar was dimmer. This suggests the visuomotor system compensates for changes in visual latency due to luminance variation, despite uncorrected lags in conscious perception.

Differences in Perceptual Latency Estimated from Judgments of Temporal Order, Simultaneity and Duration are Inconsistent

Differences in perceptual latency (ΔL) for two stimuli, such as an auditory and a visual stimulus, can be estimated from temporal order judgments (TOJ) and simultaneity judgments (ΔJ), but previous research has found evidence that ΔL estimated from these tasks do not coincide. Here, using an auditory and a visual stimulus we confirmed this and further show that ΔL as estimated from duration judgments also does not coincide with ΔL estimated from TOJ or SJ. These inconsistencies suggest that each judgment is subject to different processes that bias 4L in different ways: TOJ might be affected by sensory interactions, a bias associated with the method of single stimuli and an order difficulty bias; SJ by sensory interactions and an asymmetrical criterion bias; duration judgments by an order duration bias.

Position Perception: Influence of Motion With Displacement Dissociated From the Influence of Motion Alone

When humans view a moving object, the spatial lag in perception expected from neural delays may be partially corrected by motion mechanisms biasing perceived position. The drifting-Gabor illusion seems to support this view: the perceived location of a static envelope filled with a moving pattern is shifted in the direction of motion. To test whether this shifting mechanism also extrapolates the position of moving displacing objects, we compared the perceptual position shift for drifting versus displacing Gabors when the motion is toward the fovea and when the motion is away from the fovea. For displacing Gabors, the shift was much greater for motion toward the fovea, whereas for drifting Gabors, the shift was greater for motion away from the fovea. This dissociation suggests that the illusions are caused by different mechanisms.