Phosphene Object Perception Employs Holistic Processing During Early Visual Processing Stage

Psychophysical studies have verified the possibility of recovering the visual ability by the form of low-resolution format of images, that is, phosphene-based representations. Our previous study has found that early visual processing for phosphene patterns is configuration based. This study further investigated the configural processing mechanisms of prosthetic vision by analyzing the event-related potential components (P1 and N170) in response to phosphene face and non-face stimuli. The results reveal that the coarse processing of phosphenes involves phosphene-specific holistic processing that recovers separated phosphenes into a gestalt; low-level feature processing of phosphenes is also enhanced compared with that of normal stimuli due to increased contrast borders introduced by phosphenes; while fine processing of phosphene stimuli is impaired reflected by reduced N170 amplitude because of the degraded detailed features in the low-resolution format representations. Therefore, we suggest that strategies that can facilitate the specific holistic processing stages of prosthetic vision should be considered in order to improve the performance when designing the visual prosthesis system.