Echolocation: An Action-Perception Phenomenon

Abstract

Echolocation is a genuine human ability that is closely related to localization of reflected sounds. It is part of the scarcely studied and promising field of the percepto-cognitive processes involved in everyday audition of non-verbal sounds. It implies the use of self-generated sounds (original or direct signal) with the specific purpose of obtaining auditory information (reflected signal) to locate and recognize unseen silent objects. This ability turns out to be crucial for the achievement of the independent mobility of the blind person, an aspect that is severely affected by blindness. During the 40?s a rigorous research program was put forward in order to elucidate the sensory basis of echolocation. A series of ingenious tests was designed in which tactile or auditory input was artificially suppressed, one at a time. None of the subjects was able to perceive the object in the last case. Later studies inquired into the discriminatory aspects of echolocation and two auditory fusion phenomena, repetition pitch and the precedence effect, have recently been postulated as possible underlying psycho-acoustic mechanisms. According to the new cognitive and ecological paradigms in perception, it is assumed that the primary function of the auditory system is to determinate (to localize and recognize) the characteristics of the sound source through the sounds emitted by it. Within this context, it has been argued that echolocation is a variant of that general process. Two recently established scientific paradigms have enriched the study of this ability: the sensorimotor contingency theory and the sensory substitution perspective. We present a brief historical revision of the main studies that have been carried out on this particular phenomenon, our own included, with special emphasis in its treatment within the context of embodied cognition theories.