Regularity detection by haptics and vision.

Abstract

For vision, mirror-reflectional symmetry is usually easier to detect when it occurs within 1 object than when it occurs across 2 objects. The opposite pattern has been found for a different regularity, repetition. We investigated whether these results generalize to our sense of active touch (haptics). This was done to examine whether the interaction observed in vision results from intrinsic properties of the environment, or whether it is a consequence of how that environment is perceived and explored. In 4 regularity detection experiments, we haptically presented novel, planar shapes and then visually presented images of the same shapes. In addition to modality (haptics, vision), we varied regularity-type (symmetry, repetition), objectness (1, 2) and alignment of the axis of regularity with respect to the body midline (aligned, across). For both modalities, performance was better overall for symmetry than repetition. For vision, we replicated the previously reported regularity-type by objectness interaction for both stereoscopic and pictorial presentation, and for slanted and frontoparallel views. In contrast, for haptics, there was a 1-object advantage for repetition, as well as for symmetry when stimuli were explored with 1 hand, and no effect of objectness was found for 2-handed exploration. These results suggest that regularity is perceived differently in vision and in haptics, such that regularity detection does not just reflect modality-invariant, physical properties of our environment. (PsycINFO Database Record

Effects of Line Separation and Exploration on the Visual and Haptic Detection of Symmetry and Repetition

“…Our results for visual regularity detection confirmed this prediction. Converging evidence for this interaction between the effects of objectness and regularity-type on vision has been reported when objectness is manipulated using planar shapes like those shown in Figure 1 (Baylis & Driver, 1995; Bertamini, 2010; Bertamini et al, 1997; Koning & Wagemans, 2009; Cecchetto & Lawson, 2016). Further discussion of these results for vision is deferred until we have described the Results of Experiments 2 and 3, which investigated the interaction between regularity-type and line separation for haptic regularity detection.…”

“…However, importantly, when we manipulated perceived objectness in previous experiments using closed-contour, planar stimuli rather than line separation (Cecchetto & Lawson, 2016; see Figure 2), we obtained an interaction between objectness and regularity-type for vision but not for haptics. Based on these findings, if haptics again behaves differently to vision, in Experiment 2 compared to Experiment 1, we would not predict a greater influence of line separation when haptically detecting symmetry compared to repetition.…”

“…The pairs of lines were based on 20 of the 40 unique lines used in Experiment 1. These 20 lines were selected to span the range of difficulty that we observed in Experiment 1 of Cecchetto and Lawson (2016), which used the same lines, see Figure 3. This was done by ordering performance for regularity detection for each line from best to worst and then selecting alternate lines.…”

“…Cecchetto and Lawson (2016) found that there was an important difference between visual and haptic regularity detection. For vision, we found a one-object advantage for detecting symmetry and a two-objects advantage for detecting repetition, replicating the interaction reported by Koning and Wagemans (2009) and others.…”

“…Van der Helm and Treder’s (2009) findings indicated that the visual system treats anti-regularities differently to regularities. All of the studies discussed so far tested anti-repetition (Baylis & Driver, 1995; Bertamini, 2010; Bertamini et al, 1997; Koning & Wagemans, 2009; Cecchetto & Lawson, 2016). Van der Helm and Treder therefore argued that none of these studies actually tested whether repetition detection was easier for two-objects compared to one-object stimuli.…”