Perceptual grouping and distance estimates in typical and atypical development: Comparing performance across perception, drawing and construction tasks

Abstract

Perceptual grouping is a pre-attentive process which serves to group local elements into global wholes, based on shared properties. One effect of perceptual grouping is to distort the ability to estimate the distance between two elements. In this study, biases in distance estimates, caused by four types of perceptual grouping, were measured across three tasks, a perception, a drawing and a construction task in both typical development (TD; Experiment 1) and in individuals with Williams syndrome (WS; Experiment 2). In Experiment 1, perceptual grouping distorted distance estimates across all three tasks. Interestingly, the effect of grouping by luminance was in the opposite direction to the effects of the remaining grouping types. We relate this to differences in the ability to inhibit perceptual grouping effects on distance estimates. Additive distorting influences were also observed in the drawing and the construction task, which are explained in terms of the points of reference employed in each task. Experiment 2 demonstrated that the above distortion effects are also observed in WS. Given the known deficit in the ability to use perceptual grouping in WS, this suggests a dissociation between the pre-attentive influence of and the attentive deployment of perceptual grouping in WS. The typical distortion in relation to drawing and construction points towards the presence of some typical location coding strategies in WS. The performance of the WS group differed from the TD participants on two counts. First, the pattern of overall distance estimates (averaged across interior and exterior distances) across the four perceptual grouping types, differed between groups. Second, the distorting influence of perceptual grouping was strongest for grouping by shape similarity in WS, which contrasts to a strength in grouping by proximity observed in the TD participants.

Situational context is important: perceptual grouping modulates temporal perception

“…The estimate of the perceived distance between the left and middle items was dependent on the spatial context of these items [F (2, 22) = 65.354, p \ 0.001], that is, the apparent distance was shortened in DSR condition [t (11) = 6.378, p \ 0.001] but lengthened in DSS condition [t (11) = 7.565, p \ 0.001], compared with that in DSD condition. Such result indicates that perceptual grouping based on shape similarity leads to spatial distortion, consistent with previous studies (Enns and Girgus 1985;Farran and Cole 2008) and also verifying the stimulus manipulation in the present temporal task.…”

“…Such organizational process eases the figure-ground perception and usually gives rise to perceptual properties beyond those of elements that being grouped (Wagemans et al 2012). Some stimulus features, such as apparent spatial distance and brightness, are also modulated by the very process of perceptual grouping (Adelson 1993;Enns and Girgus 1985;Farran and Cole 2008). Whereas the majority of previous studies focus on the grouping process across visual space, some also indicate that perceptual organization can be carried out temporally to link successive stimuli (Herzog and Fahle 2002;Thorpe and Trehub 1989), rendering the situational context of preceding and succeeding events an important factor shaping our phenomenological experiences.…”

Eye Placement Bias Is Remarkably Robust

“…Grouping by similarity is considered a low-level, pre-attentive process ( Treisman, 1982 ) which emerges as early as 6 to 7 months of age ( Quinn et al., 2002 ). Perceptual distortion of distance due to similarity-based grouping occurs in perceptual estimations, reconstructions, and drawings, and it shows a developmental trajectory similar to the one documented here, with greatest distortions in 4-year-old children and minimal differences between 8 year olds and adults ( Farran & Cole, 2008 ). Such perceptual grouping may extend to aesthetic preferences for placement of objects surrounded by more white space ( Liu & Ko, 2017 ) and may therefore also account for elevated placement of eyes and windows in drawings of cat faces and houses, respectively ( Harrison et al., 2017 ).…”

Williams syndrome and its cognitive profile: the importance of eye movements

“…Behavioral studies have shown that participants with WS are susceptible to visual illusions to a similar extent as TD individuals. 38 , 39 Yet, Grice et al 40 demonstrated that this performance is supported by atypical neural behaviors. The Kanizsa square illusion occurs when four Pacman disks are correctly aligned so that the contours of a white square are perceived.…”