Seeing and Perceiving (2011) DOI:10.1163/187847511X584443 brill.nl/sp Tactile Picture Recognition: Errors Are in Shape Acquisition or Object Matching? Amy A. Kalia ∗ and Pawan Sinha M.I.T., Department of Brain and Cognitive Science, 46-4089, 77 Massachusetts Avenue, Cambridge, MA 02139, USA Received 1 September 2010; accepted 17 May 2011 Abstract Numerous studies have demonstrated that sighted and blind individuals find it difficult to recognize tactile pictures of common objects. However, it is still not clear what makes recognition of tactile pictures so diffi- cult. One possibility is that observers have difficulty acquiring the global shape of the image when feeling it. Alternatively, observers may have an accurate understanding of the shape but are unable to link it to a par- ticular object representation. We, therefore, conducted two experiments to determine where tactile picture recognition goes awry. In Experiment 1, we found that recognition of tactile pictures by blindfolded sighted observers correlated with image characteristics that affect shape acquisition (symmetry and complexity). In Experiment 2, we asked drawing experts to draw what they perceived after feeling the images. We found that the experts produced three types of drawings when they could not recognize the tactile pictures: (1) draw- ings that did not look like objects (incoherent), (2) drawings that looked like incorrect objects (coherent but inaccurate) and (3) drawings that looked like the correct objects (coherent and accurate). The majority of errors seemed to result from inaccurate perception of the global shape of the image (error types 1 and 2). Our results suggest that recognition of simplistic tactile pictures of objects is largely inhibited by low-level tactile shape processing rather than high-level object recognition mechanisms.  Koninklijke Brill NV, Leiden, 2011 Keywords Tactile picture perception, haptic, shape acquisition 1. Introduction Past research demonstrates that tactile picture recognition is difficult for normally- sighted and visually-impaired individuals. Observers typically recognize only 30– 40% of test images, even though the images are usually simplistic raised-line drawings of common objects (Fig. 1). However, it is trivial for sighted observers * To whom correspondence should be addressed. E-mail: akalia@mit.edu  Koninklijke Brill NV, Leiden, 2011 DOI:10.1163/187847511X584443