Neural and behavioral correlates of evidence accumulation in human click-based echolocation

Abstract

Echolocation enables blind individuals to perceive and navigate their environment by emitting clicks and interpreting their returning echoes. While expert blind echolocators demonstrate remarkable spatial accuracy, the behavioral and neural mechanisms supporting the temporal integration of spatial echoacoustic cues remain less explored. Here, we investigated the temporal dynamics of spatial information accumulation in human click-based echolocation using EEG. Blind expert echolocators and novice sighted participants localized virtual spatialized echoes derived from realistic synthesized mouth clicks, with trials presenting trains of 2-11 clicks. Behavioral results showed that blind expert echolocators significantly outperformed sighted controls in spatial localization. For these experts, localization thresholds decreased with more clicks, indicating cumulative integration of spatial cues across repeated samples. EEG decoding analyses revealed that neural representations significantly distinguished echo laterality and predicted overall spatial localization performance from the first click alone. Additionally, brain responses relative to the first click evolved systematically over successive clicks, paralleling psychophysical performance in blind echolocators and providing a possible index of perceptual information accumulation. These findings provide, to our knowledge, the first fine-grained account of temporal neural dynamics underlying click-based echolocation, directly linked to behavioral performance over multiple samples. They reveal how successive echoes are integrated over time into coherent spatial representations. Together, these results advance our understanding of the perceptual and neural mechanisms underlying echolocation and demonstrate adaptive sensory processing in the absence of vision.