The effects of motion cues on figure-ground perception across the lifespan

摘要

Figure-ground (FG) perception involves segmenting adjacent regions sharing a border into figure and background. Border convexity is one static cue that influences FG perception in a context-dependent manner: The probability of perceiving the figure on the convex side of a border increases with the number of alternating convex and homogeneously filled concave regions (Peterson & Salvagio, J Vision, 2008). This Convexity Context Effect (CCE) is reduced in older adults compared to younger adults (Lass, et. al., VSS, 2013). The reduced CCE in older observers may result from decreased competition resolution in FG patterns, making it more likely that the stimuli are interpreted as flat patterns. If so, then adding cues that indicate depth in the stimulus may enhance the CCE in seniors. We examined this hypothesis by testing younger (M=22.1 years) and older (M=65.9 years) observers in a FG task using 100 ms static displays consisting of 2 or 8 alternating lighter and darker regions of random dot textures, and dynamic displays in which the textures in adjacent regions moved in opposite directions. Froyen, Feldman, and Singh (J Vision, 2013) found that such motion evokes a strong percept of depth in younger observers. The FG task was to indicate the colour of the region that appeared to be in the foreground. Contrary to the hypothesis, the CCE exhibited by older observers was not larger for moving stimuli compared to static stimuli. This result is consistent with the idea that healthy aging alters the way that configural cues influence FG organization, even when additional cues signal depth in the displays. Currently, we are examining the possibility that seniors require longer presentation times to accurately perceive the motion (Bennett, Sekuler & Sekuler, Vis Res, 1997). We are also investigating the relationship between individual differences in perceived depth and CCEs.