Electrophysiological correlates associated with the processing of invisible and visible visual objects

Whether higher-level visual processing of visual objects can occur without awareness remains controversial. Here, the sandwich masking procedure and event-related potential (ERP) were applied to investigate the unconscious processing of visual objects. The behavioral results indicated that sandwich masking successfully eliminated visual awareness of the masked images. The ERP results revealed that early visual processing, which was reflected by the N/P100 effect, was preserved in the absence of visual awareness. However, higher-level visual processing was eliminated by sandwich masking. The present study suggests that the unconscious processing of visual objects is limited to early visual processing.