Recollection and familiarity in schizophrenia:An ERP investigation using face recognition exclusion tasks

Recent studies suggest that the recollection deficit observed in schizophrenia may not be a unitary phenomenon but could depend on the information to retrieve. Here we investigated whether the nature of the perceptual information affects recollection and familiarity in schizophrenia. ERP old/new effects were explored in 20 patients with schizophrenia and 20 healthy controls during unfamiliar face exclusion tasks, with either intrinsic (expression) or extrinsic (background) information either changing or remaining the same between study and test. Schizophrenia patients rejected old faces as distractors in a greater extent than healthy controls. The FN400 old/new effect (300-500ms) was found in both groups. It was sensitive to facial expression change for healthy controls but not schizophrenia patients. In addition, the parietal old/new effect was lower for correctly excluded faces for patients, but not for controls. This points to the conclusion that schizophrenia patients discriminate between target and non-target faces on the basis of the memory strength signal corresponding to the study-test mismatch rather than the recollection of the critical information, as observed in healthy controls. This functioning can be useful when study-test perceptual mismatch must be detected but, in return, can lead to the over-exclusion of old stimuli.

Age-related changes in the neural dynamics of bottom-up and top-down processing during visual object recognition: an electrophysiological investigation

When recognizing objects in our environments, we rely on both what we see and what we know. While older adults often display increased sensitivity to top-down influences of contextual information during object recognition, the locus of this increased sensitivity remains unresolved. To examine the effects of aging on the neural dynamics of bottom-up and top-down visual processing during rapid object recognition, we probed the differential effects of object perceptual ambiguity and scene context congruity on specific EEG event-related potential components indexing dissociable processes along the visual processing stream. Older adults displayed larger behavioral scene congruity effects than young adults. Older adults' larger visual P2 amplitudes to object perceptual ambiguity (as opposed to the scene congruity P2 effects in young adults) suggest continued resolution of perceptual ambiguity that interfered with scene congruity processing, while post-perceptual semantic integration (as indexed by N400) remained largely intact. These findings suggest that compromised bottom-up perceptual processing in healthy aging leads to an increased involvement of top-down processes to resolve greater perceptual ambiguity during object recognition.

Reciprocal semantic predictions drive categorization of scene contexts and objects even when they are separate

Visual categorization improves when object-context associations in scenes are semantically consistent, thus predictable from schemas stored in long-term memory. However, it is unclear whether this is due to differences in early perceptual processing, in matching of memory representations or in later stages of response selection. We tested these three concurrent explanations across five experiments. At each trial, participants had to categorize a scene context and an object briefly presented within the same image (Experiment 1), or separately in simultaneous images (Experiments 2–5). We analyzed unilateral (Experiments 1, 3) and bilateral presentations (Experiments 2, 4, 5), and presentations on the screen’s horizontal midline (Experiments 1–2) and in the upper and lower visual fields (Experiments 3, 4). In all the experiments, we found a semantic consistency advantage for both context categorization and object categorization. This shows that the memory for object-context semantic associations is activated regardless of whether these two scene components are integrated in the same percept. Our study suggests that the facilitation effect of semantic consistency on categorization occurs at the stage of matching the percept with previous knowledge, supporting the object selection account and extending this framework to an object-context reciprocal influence on matching processes (object-context selection account).

An ERP investigation of item-scene incongruity at encoding on subsequent recognition

The aim of the present study was to investigate how item-scene incongruity at encoding influences subsequent item recognition and the associated event-related potential (ERP) old/new effects. Participants (N = 26) studied pictures showing an item in a scene, either in a congruent condition (e.g., a tent in a field) or an incongruent condition (e.g., a shower cabin in a field). Items were presented alone at test. Behavioral data revealed a benefit of incongruent information, with greater source memory performance but no significant effect on old/new recognition judgments. Longer response times for old compared to new items showed that participants not only evaluated the old-new status of objects during recognition, but also worked already on the scene context decision relative to the source memory judgment. An ERP incongruity effect was found at study, with greater N400 amplitude in the incongruent condition than the congruent condition. During recognition, the results provide evidence that item-scene incongruity at study increases the amplitude of ERP old/new effects. A mid-frontal N400 old/new effect was found in the early time window (300-500 ms), and a right frontal sub-component was modulated by item-scene incongruity at encoding. The modulation observed in the later time window (500-800 ms) confirmed previous studies showing that the parietal old/new effect reflects the retrieval of episodic contextual details. The present study shows that the magnitude of ERP old/new effects is sensitive to item-scene incongruity at encoding from the early time window in the right frontal region to the later retrieval processes.