Jordan Lass

Effects of aging on figure-ground perception: Convexity context effects and competition resolution

We examined age-related differences in figure-ground perception by exploring the effect of age on Convexity Context Effects (CCE; Peterson & Salvagio, 2008). Experiment 1, using Peterson and Salvagios procedure and black and white stimuli consisting of 2 to 8 alternating concave and convex regions, established that older adults exhibited reduced CCEs compared to younger adults. Experiments 2 and 3 demonstrated that this age difference was found at various stimulus durations and sizes. Experiment 4 compared CCEs obtained with achromatic stimuli, in which the alternating convex and concave regions were each all black or all white, and chromatic stimuli in which the concave regions were homogeneous in color but the convex regions varied in color. We found that the difference between CCEs measured with achromatic and colored stimuli was larger in older than in younger adults. Our results are consistent with the hypothesis that the senescent visual system is less able to resolve the competition among various perceptual interpretations of the figure-ground relations among stimulus regions.

Effects of Bezel Size in Large Tiled Display Gaming

Many spatial UI systems (e.g., VR) rely on large displays. One method of building large high-resolution displays is to use multiple HD monitors as tiles in a single large display. The downside is the presence of monitor borders -- bezels -- between each tile in such a display. We present a study looking at the impact of bezel width on game playing on a large tiled display.

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

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. Meeting abstract presented at VSS 2015.

Effects of interior bezel size and configuration on gaming performance with large tiled displays

We present two experiments on large tiled displays used for fast-action gaming. Using a simulated tiled display, we assess the effects of interior bezel size, and configuration in a top-down arcade style space shooter game with many moving objects. Our experiments also investigate the effect of bezel compensation. The first experiment examines bezel size independent of configuration, using simulated bezel sizes ranging from 0 (i.e., no bezels) to 4 cm in a 3×3 grid configuration. Results of the experiment indicate minimal effects for bezel size and compensation. The second experiment fixed bezel size at 4 cm and instead varies configuration from a single display up to a 3×3 grid of simulated displays. Results of this study indicate that while the 1×2 performed worse in certain metrics, globally, the effects of configuration were similarly small.