Constantino Méndez-Bértolo

Looking at emotional words is not the same as reading emotional words: Behavioral and neural correlates

Recent research suggests that the allocation of attentional resources to emotional content during word processing might be sensitive to task requirements. This question was investigated in two tasks with similar instructions. The stimuli were positive, negative, and neutral nouns. Participants had to identify meaningful words embedded in a stream of non-recognizable stimuli (task 1) or pseudowords (task 2). Task 1 could be successfully performed on the basis of the perceptual features whereas a lexico-semantic analysis was required in task 2. Effects were found only in task 2. Positive nouns were identified faster, with fewer errors and elicited larger amplitude in an early negativity. Also, the amplitude of a late positivity was larger for both positive and negative nouns than for neutral nouns. It is concluded that some degree of linguistic processing is needed to direct attention to the affective content during word processing.

Electrophysiological differences in the processing of affective information in words and pictures.

It is generally assumed that affective picture viewing is related to higher levels of physiological arousal than is the reading of emotional words. However, this assertion is based mainly on studies in which the processing of either words or pictures has been investigated under heterogenic conditions. Positive, negative, relaxing, neutral, and background (stimulus fragments) words and pictures were presented to subjects in two experiments under equivalent experimental conditions. In Experiment 1, neutral words elicited an enhanced late positive component (LPC) that was associated with an increased difficulty in discriminating neutral from background stimuli. In Experiment 2, high-arousing pictures elicited an enhanced early negativity and LPC that were related to a facilitated processing for these stimuli. Thus, it seems that under some circumstances, the processing of affective information captures attention only with more biologically relevant stimuli. Also, these data might be better interpreted on the basis of those models that postulate a different access to affective information for words and pictures.

Arousal contributions to affective priming: electrophysiological correlates.

Current models of affective processing postulate that not only valence but also the arousal dimension characterizes the emotional experience. However, up-to-date research on affective priming has mainly focused on the contributions of valence congruency to priming. In this study, the authors explored the possible influence of arousal in priming processes. For this purpose, event-related potentials and reaction times were measured in response to high- and low-arousing positive targets that were either congruent or incongruent in arousal with a prime word. Priming arousal did not influence reaction times. By contrast, the processing of high-arousing targets was facilitated by a previous exposure to a congruent prime, as reflected by the reduction in the amplitude of a late positive component around 500 ms that has been thought to reflect attentional and memory processes. These results diverge from the findings of previous studies that primed valence and suggest a differential contribution of arousal and valence to affective priming.

Word frequency modulates the processing of emotional words: convergent behavioral and electrophysiological data.

The processing of high frequency (HF) words is speeded as compared to the processing of low frequency (LF) words, which is known as the word frequency effect. This effect has been suggested to occur at either a lexical access or in a decision processing stage. Previous work has shown that word frequency influenced the processing of emotional content at both neural and behavioral levels. However, the results of these studies lead to discrepant findings because some of the variables that have shown to impact the processing of affective information were not always controlled. In order to make a better characterization of frequency effects on emotional word processing, event related potentials (ERPs) and reaction times to HF and LF negative and neutral nouns were measured as participants performed a lexical decision task. Temporal and spatial component analyses were used to detect and quantify, in a reliable way, those components associated with the interaction between word frequency and emotion. LF negative nouns were recognized faster and more accurately than LF neutral nouns whereas no differences were found in the HF word comparison. Also, LF neutral words elicited reduced amplitudes in a late positive component (P450) as compared to LF negative words. These findings might be reflecting a different involvement of attentional mechanisms during the evaluation of lexical information that benefits the processing of LF negative nouns.

High arousal words influence subsequent processing of neutral information: Evidence from event-related potentials

Recent data suggest that word valence modulates subsequent cognitive processing. However, the contribution of word arousal is less understood. In this study, behavioral and electrophysiological measures to neutral nouns and pseudowords that were preceded by either a high-arousal or a low-arousal word were recorded during a lexical decision task. Effects were found at an electrophysiological level. Target words and pseudowords elicited enhanced N100 amplitudes when they were preceded by high- compared to low-arousing words. This effect may reflect perceptual potentiation during the allocation of attentional resources when the new stimulus is processed. Enhanced amplitudes in a late positivity when target words and pseudowords followed high-arousal primes were also observed, which could be related to sustained attention during supplementary analyses at a post-lexical level.

Event-related potential correlates of visual identity negative priming unbiased by trial-by-trial effects

Negative priming (NP) refers to slowed reaction times and/or less accurate responses in people responding to a target that was ignored on a previous trial. Although extensive research with behavioral measures has been conducted, little is known about the electrophysiological mechanisms underlying this effect. The few previous studies carried out have led to contradictory results, supporting either episodic-retrieval or inhibition-based theoretical perspectives. In this study, we analyzed the ERP correlates of negative priming by using an experimental global context which, similar to the NP standard context, included Attended repetition trials. In addition, we presented relevant stimuli in separate blocks instead of the more usual randomized design. The NP effect can be biased by strategies adopted by participants when attended and ignored repetition trials are presented randomly. Specifically, we observed an enhanced N2 when a distractor from the previous trial became the target in the next trial. It is supposed that this finding reflects the involvement of additional attentional resources in the selection of a previously inhibited distractor as the new target stimuli.

Early effects of emotion on word immediate repetition priming: electrophysiological and source localization evidence.

The processing of a stimulus benefits from the previous exposure of an identical stimulus, which is known as immediate repetition priming (IRP). Although several experimental manipulations modulate the size of this effect, the influence of affective information is still unclear. In order to explore the temporo–spatial characteristics of the interaction between emotion and IRP, event-related potentials (ERPs) to negative and neutral target words were measured during a lexical decision task in an IRP paradigm. Temporal and spatial versions of principal components analyses were used to detect and quantify those ERP components associated with IRP. A source localization procedure provided information on the neural origin of these components. Behavioural analyses showed that reaction times to repeated negative and neutral words differed from those to unrepeated negative and neutral words, respectively. However, the interaction between repetition and emotion was only marginally significant. In contrast, ERP analyses revealed specific IRP effects for negative words: Repeated negative words elicited reduced P120/enhanced N170 effects and weaker activation suppression in the left inferior frontal gyrus than did unrepeated negative words. These results suggest that a word’s negative content captures attention interfering with IRP mechanisms, possibly at an early semantic stage of processing.