Abstract
Top-down influences allow the visual system to perceive globally meaningful structures in spatial patterns that may be locally noisy. This has been demonstrated in classic effects such as the Dalmation dog picture and black-and-white thresholded Mooney images (Gregory, 1970; Mooney, 1957). Yet, in the case of vision, global spatial organization is facilitated by a large field of view that allows the image to be viewed in a few, or even just a single, glance. Is global perceptual organization a necessary pre-requisite for the manifestation of top-down facilitation? The haptic modality provides an opportunity to address this question given the sequential nature of haptic exploration and the resulting dominance of local shape processing (Berger and Hatwell, 1993; Lakatos and Marks, 1999; Lederman and Klatzky, 2009; Panday, Tiest and Kappers, 2012; Puspitawati, Jebrane and Vinter, 2013). Here, we examined whether 2D haptic image recognition is enhanced by top-down knowledge, and whether prior visual experience modulates this enhancement. Congenitally blind and sighted participants felt shapes embedded in noise on a refreshable Braille display. The images became progressively less noisy until participants recognized the shape. Overall, blind individuals recognized the shapes in higher levels of noise compared to sighted individuals (p = 0.011), suggesting that modality-specific experience enhances recognition of noisy tactile patterns. When the shapes were presented for a second time, both blind (p = 0.019) and sighted (p = 0.003) participants recognized them in higher levels of noise compared to novel shapes, demonstrating an effect of top-down knowledge on haptic spatial perception that is independent of visual experience. We conclude that the influence of top-down knowledge on the interpretation of ambiguous spatial patterns generalizes across sensory modalities.
Meeting abstract presented at VSS 2016