Visual adaptation reveals asymmetric spatial frequency tuning for motion

Abstract

This study investigated the spatial frequency selectivity of the human visual motion system using the technique of adaptation in which motion aftereffect (MAE) duration was taken as an index of aftereffect magnitude. Eight observers adapted to two vertically oriented, oppositely drifting, luminance-defined gratings that were spatially separated in the vertical dimension. The spatial frequency of the adaptation patterns spanned a 3-octave range (0.25 to 2 c/deg) and drifted at 5 Hz. Following adaptation (20 s), two stationary test patterns were presented and MAE duration was measured. The spatial frequency difference between the adaptation and test patterns was varied from -2.5 to 2.5 octaves in 0.5 octave steps. MAE tuning functions at the lowest adaptation frequency (0.25 c/deg) were bandpass and reasonably symmetric. However, as the spatial frequency of the adaptation patterns increased, overall MAE duration decreased and the shape of the tuning functions became markedly asymmetric. This asymmetry was characterized by a MAE peak that was centered approximately 1 octave below the adaptation frequency. The results are consistent with recent masking studies (C. V. Hutchinson & T. Ledgeway, 2007) and may reflect either asymmetric spatial frequency selectivity of underlying motion units or frequency-specific interactions (e.g. inhibition) between motion sensors tuned to different spatial frequencies.

Short-latency ocular following responses to motion stimuli are strongly affected by temporal modulations of the visual content during the initial fixation period

“…Surprisingly, the suppression was maximal when the SF of the moving pattern was much lower (2.6, 2.0, and 3.3 times) than that of the fixation one, and it is not trivial to imagine a mechanism which would account for such a mismatch. However, this finding mimics similar observations made in earlier MAE experiments ( Ledgeway & Hutchinson, 2009 ; von Grunau & Dube, 1992 ); although in these latter studies the mismatch only developed for higher SF adapting stimuli. Hutchinson and Ledgeway (2007) observed similar phenomenon while measuring the SF tuning of motion detection mechanisms using the technique of visual masking.…”

“…In those experiments, the mismatch was found with large stimuli (20 × 20 degrees, close to stimulus size in our study as well), but not with small ones (2.5 × 2.5 degrees). In 2009, they reasoned that “our adaptation results, like those revealed by masking, appear to be mediated by image size” ( Ledgeway & Hutchinson, 2009 ). This dependence on stimulus size might suggest that response normalization mechanisms are subject to the adaptive changes as well ( Solomon & Kohn, 2014 ).…”

Antagonism between fine and coarse motion sensors depends on stimulus size and contrast

“…The antagonism could help explain reversals in perceived direction of motion of second-order modulations (Cropper, Kvansakul, & Johnston, 2009) and the asymmetric shape of the motion after-effect tuning functions (Ledgeway & Hutchinson, 2009) and could also help explain why subjects judge motion direction based on motion signals from low spatial frequencies rather than high spatial frequencies (Hayashi, Sugita, Nishida, & Kawano, 2010).…”

Linguistic Representations of Motion Do Not Depend on the Visual Motion System

“…This illusion of motion is known as a motion aftereffect (for a review, see Mather, Pavan, Campana, & Casco, 2008). Motion adaptation and the motion aftereffect have been used extensively to examine the spatiotemporal tuning of mechanisms operating during the early stages of visual motion processing (Bex, Verstraten, & Mareschal, 1996;Graham, 1989;Ledgeway & Hutchinson, 2009;Mareschal, Ashida, Bex, Nishida, & Verstraten, 1997).…”