Correlation between vividness of visual imagery and echolocation ability in sighted, echo-naïve people.

The ability of humans to echolocate has been recognized since the 1940s. Little is known about what determines individual differences in echolocation ability, however. Although hearing ability has been suggested as an important factor in blind people and sighted-trained echolocators, there is evidence to suggest that this may not be the case for sighted novices. Therefore, non-auditory aspects of human cognition might be relevant. Previous brain imaging studies have shown activation of the early 'visual', i.e. calcarine, cortex during echolocation in blind echolocation experts, and also during visual imagery in blind and sighted people. Therefore, here we investigated the relationship between echolocation ability and vividness of visual imagery (VVI). Twenty-four sighted echolocation novices completed Marks' (Br J Psychol 1:17-24, 1973) VVI questionnaire and they also performed an echolocation size-discrimination task. Furthermore, they participated in a battery of auditory tests that determined their ability to detect fluctuations in sound frequency and intensity, as well as hearing differences between the right and left ear. A correlational analysis revealed a significant relationship between participants' VVI and echolocation ability, i.e. participants with stronger VVI also had higher echolocation ability, even when differences in auditory abilities were taken into account. In terms of underlying mechanisms, we suggest that either the use of visual imagery is a strategy for echolocation, or that visual imagery and echolocation both depend on the ability to recruit calcarine cortex for cognitive tasks that do not rely on retinal input.