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

Abstract

Abstract. Detection of regularities (e.g., symmetry, repetition) can be used to investigate object and shape perception. Symmetry and nearby lines may both signal that one object is present, so moving lines apart may disrupt symmetry detection, while repetition may signal that multiple objects are present. Participants discriminated symmetrical/irregular and repeated/irregular pairs of lines. For vision, as predicted, increased line separation disrupted symmetry detection more than repetition detection. For haptics, symmetry and repetition detection were similarly disrupted by increased line separation; also, symmetry was easier to detect than repetition for one-handed exploration and for body midline-aligned stimuli, whereas symmetry was harder to detect than repetition with two-handed exploration of stimuli oriented across the body. These effects of exploration and stimulus orientation show the influence of modality-specific processing rather than properties of the external world on regularity detection. These processes may, in turn, provide insights into the nature of objectness in vision and in touch.

The role of contour polarity, objectness, and regularities in haptic and visual perception

“…For vision, symmetry is usually easier to detect within one object, whereas repetition is easier to detect across two objects. For haptics, we have not found this interaction between regularity type and objectness (Cecchetto & Lawson, Journal of Experimental Psychology: Human Perception and Performance, 43, 103–125, 2017 ; Lawson, Ajvani, & Cecchetto, Experimental Psychology, 63, 197–214, 2016 ). However, our studies used repetition stimuli with mismatched concavities, convexities, and luminance, and so had mismatched contour polarities.…”

“…Irregular stimuli are not shown here, but they were identical to the regular stimuli except that the left and right critical contours were created from two different, unique lines. Top row: Pairs of lines which are not bound to surfaces, similar to the stimuli used by Lawson, Ajvani, and Cecchetto ( 2016 ). Second and third rows: Same pairs of lines used to create the outline contours of within-1object:outer-sides and between-2objects:facing-sides stimuli, similar to the stimuli used by Cecchetto and Lawson ( 2017 ).…”

“…Visual symmetry is usually easier to detect than other regularities such as repetition (Baylis & Driver, 1994 , 1995 ; Mach, 1886 /1959) and seems to have greater salience than repetition (Treder & van der Helm, 2007 ). Understanding why and when symmetry detection is often efficient requires explaining the well-established interaction between regularity type and objectness (Koning & Wagemans 2009 ; see also Baylis & Driver, 1995 , 2001 ; Bertamini, Friedenberg, & Kubovy, 1997 ; Cecchetto & Lawson, 2017 ; Lawson et al, 2016 ). The exact nature of this interaction varies across different studies (Koning & Wagemans, 2009 ).…”

“…Instead, some other factor must be driving the interaction. Koning and Wagemans ( 2009 ; see also Cecchetto & Lawson, 2017 ; Lawson et al, 2016 ) argued that the Regularity Type × Objectness interaction might arise because symmetry and repetition provide different cues about the world. Visual regularities may provide important information about how to segment a scene into objects, with symmetry used to signal the presence of a single object, and repetition used to indicate the presence of multiple, similarly shaped objects (Cecchetto & Lawson, 2017 ).…”

Effects of Handedness and Viewpoint on the Imitation of Origami-Making

“…People are better at action prediction for images of tools viewed from the perspective that they would see when using them [58]. Furthermore, in haptic (active touch) tasks, recognition is easier when objects are explored from the orientation typically used to manipulate them ( [59], but see [60]). However, none of the previous studies on viewpoint also tested the interaction with handedness.…”