Search

When tracking an object moving in depth, the visual system should take changes of eye vergence into account to judge theobject’s 3D speed correctly. Previous work has shown that extraretinal information about changes in eye vergence isexploited when judging the sign of 3D motion. Here, we ask whether extraretinal signals also affect judgments of 3D speed.Observers judged the speed of a small target surrounded by a large background. To manipulate extraretinal information,we varied the vergence demand of the entire stimulus sinusoidally over time. At different phases of vergence pursuit,we changed the disparity of the target relative to the background, leading observers to perceive approaching target motion.We determined psychometric functions for the target’s approach speed when the eyes were (1) converging, (2) diverging,(3) maximally converged (near), and (4) maximally diverged (far). The target’s motion was reported as faster duringconvergence and slower during divergence but perceived speed was little affected at near or far vergence positions. Thus,3D speed judgments are affected by extraretinal signals about changes in eye rotation but appear unaffected by theabsolute orientation of the eyes. We develop a model that accounts for observers’ judgments by taking a weighted averageof the retinal and extraretinal signals to target motion.Keywords: binocular vision, depth, eye movements, motionV3DCitation: Lugtigheid, A. J., Brenner, E., & Welchman, A. E. (2011). Speed judgments of three-dimensional motionincorporate extraretinal information. Journal of Vision, 11(13):1, 1–11, http://www.journalofvision.org/content/11/13/1,doi:10.1167/11.13.1.

It was recently shown that expert face perception relies on the extraction of horizontally oriented visual cues. Picture-plane inversion was found to eliminate horizontal, suggesting that this tuning contributes to the specificity of face processing. The present experiments sought to determine the spatial frequency (SF) scales supporting the horizontal tuning of face perception. Participants were instructed to match upright and inverted faces that were filtered both in the frequency and orientation domains. Faces in a pair contained horizontal or vertical ranges of information in low, middle, or high SF (LSF, MSF, or HSF). Our findings confirm that upright (but not inverted) face perception is tuned to horizontal orientation. Horizontal tuning was the most robust in the MSF range, next in the HSF range, and absent in the LSF range. Moreover, face inversion selectively disrupted the ability to process horizontal information in MSF and HSF ranges. This finding was replicated even when task difficulty was equated across orientation and SF at upright orientation. Our findings suggest that upright face perception is tuned to horizontally oriented face information carried by intermediate and high SF bands. They further indicate that inversion alters the sampling of face information both in the orientation and SF domains.

It is widely debated whether fast phases of the reflexive optokinetic nystagmus (OKN) share properties with another class of fast eye movements, visually guided saccades. Conclusions drawn from previous studies were complicated by the fact that a subject's task influences the exact type of OKN: stare vs. look nystagmus. With our current study we set out to determine in the same subjects the exact dynamic properties (main sequence) of various forms of fast eye movements. We recorded fast phases of look and stare nystagmus as well as visually guided saccades. Our data clearly show that fast phases of look and stare nystagmus differ with respect to their main sequence. Fast phases of stare nystagmus were characterized by their lower peak velocities and longer durations as compared to fast phases of look nystagmus. Furthermore we found no differences between fast phases of stare nystagmus evoked with limited and unlimited dot lifetimes. Visually guided saccades were on the same main sequence as fast phases of look nystagmus, while they had higher peak velocities and shorter durations than fast phases of stare nystagmus. Our data underline the critical role of behavioral tasks (e.g., reflexive vs. intentional) for the exact spatiotemporal characteristics of fast eye movements.