Noesselt Toemme, Fendrich Robert, Bonath Bjoern, Tyll Sascha, Heinze Hans-Jochen
Department of Neurology II and Center for Advanced Imaging, Leipziger Str.44, 39120 Magdeburg, Germany.
Brain Res Cogn Brain Res. 2005 Oct;25(2):443-58. doi: 10.1016/j.cogbrainres.2005.07.005. Epub 2005 Aug 29.
We investigated the effect of visual eccentricity and spatial alignment on judgments of audiovisual synchrony. Sequences of flashes at 4, 6, and 8 Hz were presented centrally, or at horizontal eccentricities of 6 degrees or 18 degrees. Concurrent sequences of clicks were presented at the same rate as the flashes, or at higher or lower rates. Subjects judged whether the flash rate was the same as (synchronous with), faster than, or slower than the click rate. With the 4- and 6-Hz flash rates, subjects' judgments of audiovisual synchrony increased with increasing eccentricity, but only when the click rate was more rapid than the flash rate. This effect remained even when the size of the peripheral visual stimuli was adjusted to compensate for cortical magnification, and was not significantly influenced by the spatial proximity of the auditory and visual signals. However, it was absent when the auditory and visual stimuli were presented serially rather than concurrently. With the 8-Hz flash rate, synchrony judgments were prevalent irrespective of eccentricity. When two serially presented flash rates were compared, visual-visual matching judgments increased with eccentricity at flash rates of 6 Hz and higher, but decreased at flash rates below 6 Hz. Finally, when two concurrent flash rates were compared, visual-visual synchrony judgments increased with eccentricity at all flash-rate combinations. Together, these results suggest that while perceptual uncertainty can play a role in synchrony judgments at rates of 6 Hz and higher, below 6 Hz eccentricity produces a widening of the window of apparent audiovisual temporal synchrony which perceptual uncertainty cannot explain.
我们研究了视觉离心率和空间对齐对视听同步判断的影响。以4Hz、6Hz和8Hz频率闪烁的序列分别呈现在视野中心，或水平离心率为6度或18度的位置。同时呈现的点击序列与闪烁序列的频率相同，或更高或更低。受试者判断闪烁频率与点击频率是否相同（同步）、更快还是更慢。对于4Hz和6Hz的闪烁频率，受试者对视听同步的判断随着离心率的增加而增加，但仅当点击频率比闪烁频率更快时才会如此。即使调整周边视觉刺激的大小以补偿皮质放大效应，这种效应仍然存在，并且不受听觉和视觉信号空间接近度的显著影响。然而，当听觉和视觉刺激相继而非同时呈现时，这种效应不存在。对于8Hz的闪烁频率，无论离心率如何，同步判断都很普遍。当比较两个相继呈现的闪烁频率时，在6Hz及以上的闪烁频率下，视觉-视觉匹配判断随着离心率的增加而增加，但在低于6Hz的闪烁频率下则下降。最后，当比较两个同时呈现的闪烁频率时，在所有闪烁频率组合下，视觉-视觉同步判断都随着离心率的增加而增加。总之，这些结果表明，虽然感知不确定性可能在6Hz及以上频率的同步判断中起作用，但在低于6Hz时，离心率会导致明显的视听时间同步窗口变宽，而感知不确定性无法解释这一现象。
