Event-related potentials (ERP) were recorded during a task involving the short-term recognition of unfamiliar faces. The purpose was to study the effects of changing the intrinsic context (facial expression) and/or the extrinsic context (background) between the encoding and recognition of a face. The new face caused an increase in the parietal N170 amplitude, but this component was not affected by contextual modifications. In contrast, the frontal N200 was very sensitive to context changes. There was also a well-defined, late parietal component modulated by the processing of information relevant to the face recognition decision. This late positive component reached its amplitude peak when the decision criterion was the strictest. The results obtain showed that ERP can be modulated by these context variations even though they are irrelevant to the task at hand.

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This study confirms the presence of a deficit in facial affect recognition, and also of dysfunctional manipulation in configural information in antipsychotic-free patients. Negative symptoms and poor processing of configural information explained a substantial part of the deficient recognition of facial affect. We speculate that this deficit may be caused by several factors, among which independently stand psychopathology and failure in correctly manipulating configural information.

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Abstract. The present study investigated the temporal dynamics of the object-scene congruity during a categorization task of objects embedded in a scene. Participants (n = 28) categorized objects in scenes as natural or man-made while event-related brain potentials (ERPs) were recorded. The object-scene associations were either congruous (e.g., a tent in a field) or incongruous (e.g., a fridge in a desert). The results confirmed that contextual congruity affects item processing in the 300–500 ms time window with larger N300/N400 complex in the incongruous than in the congruous condition. However, unlike previous work which found an effect of congruity starting at ~ 250 ms poststimulus on fronto-central regions, the earliest sign of a reliable context congruity effect arose at ~ 170 ms at left centro-parietal regions in the present study. The present results are in line with those of previous studies showing that object and context are processed in parallel with continuous interactions from 150 to 500 ms, possibly through feed-forward co-activation of populations of neurons selective to the processing of the object and its context. The present finding provides novel evidence suggesting that online context violations might affect earlier visual processes and routines of matching between possible scene-congruent activated schemas and the upcoming information about the item to process.