'Visual’ parsing can be taught quickly without visual experience during critical periods

Cases of invasive sight-restoration in congenital blind adults demonstrated that acquiring visual abilities is extremely challenging, presumably because visual-experience during critical-periods is crucial for learning visual-unique concepts (e.g. size constancy). Visual rehabilitation can also be achieved using sensory-substitution-devices (SSDs) which convey visual information non-invasively through sounds. We tested whether one critical concept – visual parsing, which is highly-impaired in sight-restored patients – can be learned using SSD. To this end, congenitally blind adults participated in a unique, relatively short (~70 hours), SSD-‘vision’ training. Following this, participants successfully parsed 2D and 3D visual objects. Control individuals naïve to SSDs demonstrated that while some aspects of parsing with SSD are intuitive, the blind’s success could not be attributed to auditory processing alone. Furthermore, we had a unique opportunity to compare the SSD-users’ abilities to those reported for sight-restored patients who performed similar tasks visually, and who had months of eyesight. Intriguingly, the SSD-users outperformed the patients on most criteria tested. These suggest that with adequate training and technologies, key high-order visual features can be quickly acquired in adulthood, and lack of visual-experience during critical-periods can be somewhat compensated for. Practically, these highlight the potential of SSDs as standalone-aids or combined with invasive restoration approaches.