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A blind human expert echolocator shows size constancy for objects perceived by echoes.

Milne, J. L. and Anello, M. and Goodale, M. A. and Thaler, L. (2015) 'A blind human expert echolocator shows size constancy for objects perceived by echoes.', Neurocase., 21 (4). pp. 465-470.


Some blind humans make clicking noises with their mouth and use the reflected echoes to perceive objects and surfaces. This technique can operate as a crude substitute for vision, allowing human echolocators to perceive silent, distal objects. Here, we tested if echolocation would, like vision, show size constancy. To investigate this, we asked a blind expert echolocator (EE) to echolocate objects of different physical sizes presented at different distances. The EE consistently identified the true physical size of the objects independent of distance. In contrast, blind and blindfolded sighted controls did not show size constancy, even when encouraged to use mouth clicks, claps, or other signals. These findings suggest that size constancy is not a purely visual phenomenon, but that it can operate via an auditory-based substitute for vision, such as human echolocation.

Item Type:Article
Keywords:Blindness, Human echolocation, Size constancy, Vision, Multisensory.
Full text:(AM) Accepted Manuscript
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Publisher statement:This is an Accepted Manuscript of an article published by Taylor & Francis Group in Neurocase on 29/05/2014, available online at:
Record Created:12 Aug 2014 09:50
Last Modified:01 Mar 2017 10:27

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