Early acquisition efficiency in visual-to-auditory sensory substitution: the role of structured learning.

Introduction: Visual-to-auditory sensory substitution converts visual information into structured sound patterns when visual input is unavailable, impaired, or experimentally restricted, thereby supporting access to information otherwise conveyed visually. Its perceptual usability depends jointly on the sensory-conversion scheme that encodes visual information into sound and on the learning conditions under which learners acquire sound-visual mappings through learning and experience. Although prior visual-to-auditory sensory-substitution studies have often evaluated substituted coding schemes or learning approaches primarily through endpoint learnability or recognition accuracy, endpoint performance alone does not characterize the temporal cost and efficiency with which usable perceptual decoding emerges during learning. Methods: This study examined whether structured learning based on information-processing principles was associated with more efficient early acquisition of sound-visual mappings in a controlled perceptual-learning model with a constant visual-to-auditory mapping framework. Acquisition-phase behavioral records from 63 blindfolded sighted adults who completed a randomized visual-to-auditory sensory-substitution learning experiment were analyzed, with 31 and 32 participants in the structured-learning and control conditions, respectively. The outcomes included correct-trial response time, total learning time, response-time variability, and inverse efficiency score. Results: Compared with the control condition, structured learning was associated with shorter correct-trial response time, lower total learning time, and lower inverse efficiency score, without a meaningful between-group difference in response-time variability. These patterns remained evident across robustness analyses and after adjustment for baseline pre-test performance. Exploratory schedule-derived analyses suggested that structured learning provided denser repeated exposure and a more staged introduction of sensory mappings. Discussion: Together, these behavioral-log findings indicate that structured learning was associated with more efficient early acquisition of sound-visual mappings and suggest that acquisition efficiency in sensory-substitution learning may be related to how those mappings are sequenced and repeated during learning.