1,721,068 research outputs found
Repetition and ERPs during emotional scene processing: A selective review
Full text linkA set of studies are reviewed that investigate the effects of repetition during scene perception on event-related potentials, elucidating perceptual, memory and emotional processes. Repetition suppression was consistently found for the amplitude of early frontal N2 and posterior P2 components, which was greatly enhanced for massed, compared to distributed, repetition. Both repetition suppression and enhancement of the amplitude of a centro-parietal positive potential (LPP) were found in specific contexts. Suppression was reliably found following a massive number of repetitions of few items, whereas enhancement is found when repetitions are spaced; enhancement was apparent both during simple free viewing as well as on an explicit recognition test. Regardless of repetition, an enhanced LPP was always found for emotional, compared to neutral, scenes. Taken together, the data suggest that different effects of massed and distributed repetitions on specific ERP components index perceptual priming, habituation, and spontaneous episodic retrieval
Cognitive control during scene categorization: The role of identity repetition and timing in congruence sequence effects
Full text linkCognitive control abilities include maintaining goal-directed behaviors in spite of the incongruence between habitual and desired responses. In interference paradigms, slower responses to incongruent compared to congruent trials are observed; this interference is reduced after incongruent trials (congruence sequential effect, CSE), suggesting that the control exerted to counteract interference in the previous trial also propagates into the following trial. Moreover, a larger CSE is observed when trial features are repeated. Binding–retrieval accounts suggest that trial features that occur in the same time frame are bound together in an episodic representation; if a feature is repeated in the next trial, the control state that was active in the previous trial is also reactivated, resulting in a modulation of congruence effects. However, previous studies that used stimulus sets characterized by intracategory variability (e.g., faces and scenes) observed CSE modulation by the repetition of response categories but were inconclusive concerning whether repeating the identity of a stimulus may modulate CSE. The present study investigates whether episodic stimulus representations include both stimulus identity and response category information, by comparing the impact of the repetition of novel pictures (no identity repetition) and of frequent pictures (in which identity is repeated over trials) in a picture–word interference task. Results indicated that stimulus identity was not critical in the modulation of CSE, and that CSE was little affected by response–stimulus interval. Altogether, the present results contribute to the understanding and theoretical specification of sequential effects
Emotional Picture Perception: Repetition Effects in Free-Viewing and during an Explicit Categorization Task
Full text linkSeveral studies have found that, despite a decrease in the overall amplitude of the late positive potential (LPP) with repeated presentation of the same picture, emotional stimuli continue to elicit a larger LPP than neutral ones. These findings seem to support the hypothesis that the affective modulation of the LPP reflects a mandatory process and does not rely on stimulus novelty. However, in these studies participants were asked to merely look at the pictures, without carrying out any additional task (free-viewing), making picture emotionality the most salient aspect of the stimulus, despite its repetition. The current study aimed to examine the impact of an explicit categorization task on the emotional processing of repeated pictures. To this purpose, ERPs to novel and repeated pictures were measured during free-viewing as well as during an explicit categorization task, where the emotional content of the pictures was task-irrelevant. The within-subject comparison between the free-viewing and task context revealed that the overall LPP habituated more rapidly in the free-viewing condition, but, more importantly, the LPP affective modulation was unaffected by task requirements during both novel and repeated presentations. These results suggest that the affective modulation of the LPP reflects an automatic engagement of cortico-limbic motivational systems, which continues to take place regardless of stimulus novelty and task context
Massed and distributed repetition of natural scenes: Brain potentials and oscillatory activity
No full textNeural measures of repetition can result in either repetition suppression or enhancement effects, with enhancement sometimes interpreted as indicating episodic retrieval, rather than stimulus habituation. Here, we manipulated whether repetitions were massed (consecutive) or distributed (intermixed) and measured event-related potentials and oscillatory activity, investigating the question of whether there is evidence of "spontaneous" episodic retrieval for distributed, but not massed, repetition. Results showed that distributed repetition uniquely prompted a significant centroparietal old-new effect as well as enhanced theta, compared to either novel presentations or massed repetitions, consistent with a hypothesis of spontaneous retrieval. Massed repetition, on the other hand, prompted repetition suppression and reduction of the N2/P2. Taken together, the data suggest that distributed repetition may facilitate later memory performance because it spontaneously retrieves prior representations
Categorization goals modulate the use of natural scene statistics
Full text linkUnderstanding natural scenes involves the contribution of bottom–up analysis and top–down modulatory processes. However, the interaction of these processes during the categorization of natural scenes is not well understood. In the current study, we approached this issue using ERPs and behavioral and computational data. We presented pictures of natural scenes and asked participants to categorize them in response to different questions (Is it an animal/vehicle? Is it indoors/outdoors? Are there one/two foreground elements?). ERPs for target scenes requiring a “yes” response began to differ from those of nontarget scenes, beginning at 250 msec from picture onset, and this ERP difference was unmodulated by the categorization questions. Earlier ERPs showed category-specific differences (e.g., between animals and vehicles), which were associated with the processing of scene statistics. From 180 msec after scene onset, these category-specific ERP differences were modulated by the categorization question that was asked. Categorization goals do not modulate only later stages associated with target/nontarget decision but also earlier perceptual stages, which are involved in the processing of scene statistics
The fate of unattended stimuli and emotional habituation: Behavioral interference and cortical changes
Full text linkThe interference produced by the viewing of emotional distractors has been interpreted as evidence that emotional cues are processed in a fairly mandatory fashion, and that they divert attention from the primary ongoing task. However, few studies have examined how behavioral emotional interference varies with repeated presentation of the same emotional distractors. In two experiments, while participants were engaged in a parity judgment task, we investigated the effects of repetition of task-irrelevant emotional pictures, as reflected in both behavioral interference (Experiments 1 and 2) and neural activity (Experiment 2). Both experiments showed that the slowing of reaction times that was observed when viewing emotional, compared to neutral, scenes disappeared after only a few repetitions, suggesting diminished attention allocation to repeated emotional pictures. Conversely, in Experiment 2, neural correlates of picture processing revealed that the late positive potential (LPP) amplitude continued to be enhanced for emotional, compared to neutral, distractors despite picture repetition and the presence of a concurrent task. Altogether, these findings suggest that while evaluative processes are mandatory, and continue to engage cortico-limbic appetitive and defensive systems even after massive repetition, as suggested by the affective modulation of the LPP, attentional processes are not necessary after several repetitions of the same stimulus, as indicated by the rapid decline of behavioral emotional interference
Understanding natural scenes: Contributions of image statistics
No full textVisual processing of natural scenes is carried out in a hierarchical sequence of stages that involve the analysis of progressively more complex features of the visual input. Recent studies have suggested that the semantic content of natural stimuli (e.g., real world photos) can be categorized based on statistical regularities in their appearance, which can be detected early in the visual processing stream. Here we review the studies which have investigated the role of scene statistics in the perception of natural scenes, focusing on both basic visual processing and specific tasks (visual search, expert categorization, emotional picture viewing). Visual processing seems to be adapted to visual regularities in the visual input, such as the amplitude-frequency relationship. Moreover, scene statistics can aid performance in specific tasks such as distinguishing animals from artifactual scenes, possibly by modulating early visual processing stages
Evaluative ratings and attention across the life span: emotional arousal and gender
Full text linkThis study was designed to investigate the evolution of emotional processing over the whole adult life span as a function of stimulus arousal and participants’ gender. To this end, self-reported affective evaluation and attentional capture prompted by pleasant and unpleasant pictures varying in arousal were measured in a large sample of participants (n = 211) balanced by gender and equally spread across seven decades from 20 to 90 years. Results showed age differences only for affective evaluation of pleasant stimuli, with opposite patterns depending on stimulus arousal. As age increased, low-arousing pleasant cues (e.g. images of babies) were experienced as more pleasant and arousing by both males and females, whereas high-arousing stimuli (e.g. erotic images) were experienced as less pleasant only by females. In contrast, emotional pictures (both pleasant and unpleasant) were effective at capturing attention in a similar way across participants, regardless of age and gender. Taken together, these findings suggest that specific emotional cues prompt different subjective responses across different age groups, while basic mechanisms involved in attentional engagement towards both pleasant and unpleasant stimuli are preserved in healthy ageing
Time will tell: Object categorization and emotional engagement during processing of degraded natural scenes
Full text linkThe aim of the present study was to examine the relationship between object categorization in natural scenes and the engagement of cortico-limbic appetitive and defensive systems (emotional engagement) by manipulating both the bottom-up information and the top-down context. Concerning the bottom-up information, we manipulated the computational load by scrambling the phase of the spatial frequency spectrum, and asked participants to classify natural scenes as containing an animal or a person. The role of the top-down context was assessed by comparing an incremental condition, in which pictures were progressively revealed, to a condition in which no probabilistic relationship existed between each stimulus and the following one. In two experiments, the categorization and response to emotional and neutral scenes were similarly modulated by the computational load. The Late Positive Potential (LPP) was affected by the emotional content of the scenes, and by categorization accuracy. When the phase of the spatial frequency spectrum was scrambled by a large amount (>58%), chance categorization resulted, and affective LPP modulation was eliminated. With less degraded scenes, categorization accuracy was higher (.82 in Experiment 1,.86 in Experiment 2) and affective modulation of the LPP was observed at a late window (>800 ms), indicating that it is possible to delay the time of engagement of the motivational systems which are responsible for the LPP affective modulation. The present data strongly support the view that semantic analysis of visual scenes, operationalized here as object categorization, is a necessary condition for emotional engagement at the electrocortical level (LPP)
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