Abstract
In active echolocation, reflections from self-generated acoustic pulses are used to represent the external environment. This ability has been described in some blind humans to aid in navigation and obstacle perception[1-4]. Echoic object representation has been described in echolocating bats and dolphins[5,6], but most prior work in humans has focused on navigation or other basic spatial tasks[4,7,8]. Thus, the nature of echoic object information received by human practitioners remains poorly understood. In two match-to-sample experiments, we tested the ability of five experienced blind echolocators to identify objects haptically which they had previously sampled only echoically. In each trial, a target object was presented on a platform and subjects sampled it using echolocation clicks. The target object was then removed and re-presented along with a distractor object. Only tactile sampling was allowed in identifying the target. Subjects were able to identify targets at greater than chance levels among both common household objects (p < .001) and novel objects constructed from plastic blocks (p = .018). While overall accuracy was indicative of high task difficulty, our results suggest that objects sampled by echolocation are recognizable by shape, and that this representation is available across sensory modalities.