Reduced flash lag illusion in early deaf individuals.

When a brief flash is quickly presented aligned with a moving target, the flash typically appears to lag behind the moving stimulus. This effect is widely known in the literature as a flash-lag illusion (FLI). The flash-lag is an example of a motion-induced position shift. Since auditory deprivation leads to both enhanced visual skills and impaired temporal abilities, both crucial for the perception of the flash-lag effect, here we hypothesized that lack of audition could influence the FLI. 13 early deaf and 18 hearing individuals were tested in a visual FLI paradigm to investigate this hypothesis. As expected, results demonstrated a reduction of the flash-lag effect following early deafness, both in the central and peripheral visual fields. Moreover, only for deaf individuals, there is a positive correlation between the flash-lag effect in the peripheral and central visual field, suggesting that the mechanisms underlying the effect in the center of the visual field expand to the periphery following deafness. Overall, these findings reveal that lack of audition early in life profoundly impacts early visual processing underlying the flash-lag effect.