Disruption of early face recognition processes by object substitution masking

Visual stimuli can fail to reach conscious awareness when surrounded by dots sharing a common onset but remaining visible after target removal, a phenomenon known as object substitution masking (OSM). We assessed the locus of substitution by recording the N170 component of the human event-related potential during a face/house classification task. Delayed-offset dots impaired target categorization, confirming the generality of object substitution masking by extending the effect to realistic, complex stimuli. Furthermore, object substitution masking eliminated the N170 amplitude difference between faces and houses, providing the first neural evidence that object substitution masking disrupts structural encoding stages during object recognition.