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Published online: 24 September 2014
© The Psychonomic Society, Inc. 2014
Abstract We used a haptic enumeration task to investigate whether enumeration can be facilitated by perceptual grouping in the haptic modality. Eight participants were asked to count tangible dots as quickly and accurately as possible, while moving their finger pad over a tactile display. In Experiment 1, we manipulated the number and organization of the dots, while keeping the total exploration area constant. The dots were either evenly distributed on a horizontal line (baseline condition) or organized into groups based on either proximity (dots placed in closer proximity to each other) or configural cues (dots placed in a geometric configuration). In Experiment 2, we varied the distance between the subsets of dots. We hypothesized that when subsets of dots can be grouped together, the enumeration time will be shorter and accuracy will be higher than in the baseline condition. The results of both experiments showed faster enumeration for the configural condition than for the baseline condition, indicating that configural grouping also facilitates haptic enumeration. In Experiment 2, faster enumeration was also observed for the proximity condition than for the baseline condition. Thus, perceptual grouping speeds up haptic enumeration by both configural and proximity cues, suggesting that similar mechanisms underlie perceptual grouping in both visual and haptic enumeration.
Keywords Haptics . Enumeration . Perceptual grouping . Gestalt principles . Proximity . Configural cues
The brain has to organize the incoming stream of perceptual information; an important mechanism in this perceptual organization is perceptual grouping. Koffka (1922) and Wertheimer (1912, 1923) were the first to formulate Gestalt principles, which describe how individual elements in the perceptual field are organized into groups. The first principle of grouping described by Wertheimer is proximity, which states that elements that are close to each other will be grouped together. Some other important and commonly used principles are similarity and good continuation. The Gestalt principle of similarity states that we tend to group items that share the same characteristics-for example, color or orientation. The Gestalt principle of good continuation states that we tend to group lines or curves that follow one another, even if some parts are hidden (Wertheimer, 1912, 1923).
A considerable amount of research has focused on...