Decomposing unpleasantness: Differential exogenous attention to disgusting and fearful stimuli

Measuring the emotion-specificity of rapid stimulus-driven attraction of attention to fearful faces: evidence from emotion categorization and a comparison with disgusted faces

In the current study, we tested whether a fear advantage-rapid attraction of attention to fearful faces that is more stimulus-driven than to neutral faces-is emotion specific. We used a cueing task with face cues preceding targets. Cues were non-predictive of the target locations. In two experiments, we found enhanced cueing of saccades towards the targets with fearful face cues than with neutral face cues: Saccades towards targets were more efficient with cues and targets at the same position (under valid conditions) than at opposite positions (under invalid conditions), and this cueing effect was stronger with fearful than with neutral face cues. In addition, this cueing effect difference between fearful and neutral faces was absent with inverted faces as cues, indicating that the fear advantage is face-specific. We also show that emotion categorization of the face cues mirrored these effects: Participants were better at categorizing face cues as fearful or neutral with upright than with inverted faces (Experiment 1). Finally, in alternative blocks including disgusted faces instead of fearful faces, we found more similar cueing effects with disgusted faces and neutral faces, and with upright and inverted faces (Experiment 2). Jointly, these results demonstrate that the fear advantage is emotion-specific. Results are discussed in light of evolutionary explanations of the fear advantage.

Attention to emotional stimuli in borderline personality disorder - a review of the influence of dissociation, self-reference, and psychotherapeutic interventions

Interactions between attention and processing of emotional stimuli shed light on both sensitivity to emotional stimuli as well as emotion dysregulation. Both of the latter processes have been proposed as central characteristics of altered emotion processing in those with borderline personality disorder (BPD). This review first summarizes the conflicting behavioural, psychophysiological and neuroimaging evidence for the hypothesis that emotional dysregulation should be reflected by higher distractibility through emotional stimuli in those with BPD. Dissociation, self-reference, as well as symptom severity modulated by psychotherapeutic interventions are proposed to help clarify divergent findings. Data suggest an association of dissociation with impaired task continuation during the presentation of interfering emotional and neutral stimuli, as well as high recruitment of neuronal attention networks together with a blunted emotional response. Considering self-reference, evidence suggests that negative rather than positive information may be more self-relevant to those with BPD. This may be due to a negative self-concept and self-evaluation. Social or trauma-relevant information attracts more attention from individuals with BPD and thus suggests higher self-relevance. After psychotherapeutic interventions, initial evidence may indicate normalization of the way attention and emotional stimuli interact in BPD. When studying attention-emotion interactions in BPD, methodological heterogeneities regarding sample, task, and stimulus characteristics need to be considered. When doing so, dissociation, self-reference, and psychotherapeutic interventions offer promising targets for future studies on attention-emotion interactions in those with BPD. This could promote a deeper insight into the affected individuals' struggle with emotions.

Decomposing valence intensity effects in disgusting and fearful stimuli: an event-related potential study

We are sensitive to valence intensity in negative emotional stimuli, but not in positive emotional stimuli, a phenomenon known as the valence intensity effect. However, whether this valence intensity effect is processed similarly within different negative stimuli, e.g., fear-inducing and disgust-inducing, remains unclear. In the present study, we investigated whether the valence intensity effects for fearful and disgusting stimuli were perceived in a unique way by using event-related potentials (ERPs). Electroencephalogram was recorded from 22 participants as they performed a standard/deviant categorization task using extremely disgusting pictures, moderately disgusting pictures, extremely fearful pictures, moderately fearful pictures, and neutral pictures. The ERP analysis revealed that the extremely fearful stimuli elicited a larger amplitude N2 than moderately fearful stimuli, whereas the extremely disgusting stimuli elicited a smaller amplitude late positive component than moderately disgusting stimuli. This study is the first to provide evidence that fear and disgust may have different valence intensity effects, which was revealed at early attention allocation stages for fearful stimuli and at late emotional evaluation stages for disgusting stimuli.

Selective looking at natural scenes: Hedonic content and gender

Choice viewing behavior when looking at affective scenes was assessed to examine differences due to hedonic content and gender by monitoring eye movements in a selective looking paradigm. On each trial, participants viewed a pair of pictures that included a neutral picture together with an affective scene depicting either contamination, mutilation, threat, food, nude males, or nude females. The duration of time that gaze was directed to each picture in the pair was determined from eye fixations. Results indicated that viewing choices varied with both hedonic content and gender. Initially, gaze duration for both men and women was heightened when viewing all affective contents, but was subsequently followed by significant avoidance of scenes depicting contamination or nude males. Gender differences were most pronounced when viewing pictures of nude females, with men continuing to devote longer gaze time to pictures of nude females throughout viewing, whereas women avoided scenes of nude people, whether male or female, later in the viewing interval. For women, reported disgust of sexual activity was also inversely related to gaze duration for nude scenes. Taken together, selective looking as indexed by eye movements reveals differential perceptual intake as a function of specific content, gender, and individual differences.

The Divergent Effects of Fear and Disgust on Inhibitory Control: An ERP Study

Negative emotional stimuli have been shown to attract attention and impair executive control. However, two different types of unpleasant stimuli, fearful and disgusting, are often inappropriately treated as a single category in the literature on inhibitory control. Therefore, the present study aimed to investigate the divergent effects of fearful and disgusting distracters on inhibitory control (both conscious and unconscious inhibition). Specifically, participants were engaged in a masked Go/No-Go task superimposed on fearful, disgusting, or neutral emotional contexts, while event-related potentials were measured concurrently. The results showed that for both conscious and unconscious conditions, disgusting stimuli elicited a larger P2 than fearful ones, and the difference waves of P3 amplitude under disgusting contexts were smaller than that under fearful contexts. These results suggest that disgusting distracters consume more attentional resources and therefore impair subsequent inhibitory control to a greater extent. This study is the first to provide electrophysiological evidence that fear and disgust differently affect inhibitory control. These results expand our understanding of the relationship between emotions and inhibitory control.

Different timing features in brain processing of core and moral disgust pictures: an event-related potentials study

Disgust, an emotion motivating withdrawal from offensive stimuli, protects us from the risk of biological pathogens and sociomoral violations. Homogeneity of its two types, namely, core and moral disgust has been under intensive debate. To examine the dynamic relationship between them, we recorded event-related potentials (ERPs) for core disgust, moral disgust and neutral pictures while participants performed a modified oddball task. ERP analysis revealed that N1 and P2 amplitudes were largest for the core disgust pictures, indicating automatic processing of the core disgust-evoking pictures. N2 amplitudes were higher for pictures evoking moral disgust relative to core disgust and neutral pictures, reflecting a violation of social norms. The core disgust pictures elicited larger P3 and late positive potential (LPP) amplitudes in comparison with the moral disgust pictures which, in turn, elicited larger P3 and LPP amplitudes when compared to the neutral pictures. Taken together, these findings indicated that core and moral disgust pictures elicited different neural activities at various stages of information processing, which provided supporting evidence for the heterogeneity of disgust.

Exogenous (automatic) attention to emotional stimuli: a review

Current knowledge on the architecture of exogenous attention (also called automatic, bottom-up, or stimulus-driven attention, among other terms) has been mainly obtained from studies employing neutral, anodyne stimuli. Since, from an evolutionary perspective, exogenous attention can be understood as an adaptive tool for rapidly detecting salient events, reorienting processing resources to them, and enhancing processing mechanisms, emotional events (which are, by definition, salient for the individual) would seem crucial to a comprehensive understanding of this process. This review, focusing on the visual modality, describes 55 experiments in which both emotional and neutral irrelevant distractors are presented at the same time as ongoing task targets. Qualitative and, when possible, meta-analytic descriptions of results are provided. The most conspicuous result is that, as confirmed by behavioral and/or neural indices, emotional distractors capture exogenous attention to a significantly greater extent than do neutral distractors. The modulatory effects of the nature of distractors capturing attention, of the ongoing task characteristics, and of individual differences, previously proposed as mediating factors, are also described. Additionally, studies reviewed here provide temporal and spatial information-partially absent in traditional cognitive models-on the neural basis of preattention/evaluation, reorienting, and sensory amplification, the main subprocesses involved in exogenous attention. A model integrating these different levels of information is proposed. The present review, which reveals that there are several key issues for which experimental data are surprisingly scarce, confirms the relevance of including emotional distractors in studies on exogenous attention.

In the grip of fear: dissociations in attentional processing of animal fearful individuals

Using a modified attention paradigm we investigated specific attentional mechanisms in processing animal feared stimuli. In this paradigm arrays of four pictures were displayed and after its disappearance from view a probe (a letter, X or P) then followed unpredictably in the location of one of the four pictures. The results showed that discriminations of probes tended to be impeded by spider stimuli, compared to snake stimuli. This effect was potentiated by high anxiety but only for those individuals fearful of spiders, since no such effect was observed for snake fearful individuals. Moreover, the discrimination of the probes was not facilitated when presented after the feared stimuli. The implications of these findings are discussed as a function of the cognitive bias involved in specific fear.

Disgust-specific modulation of early attention processes

Although threatening images are known to attract and keep our attention, little is known about the existence of emotion-specific attention effects. In this study (N=46), characteristics of an anticipated, disgust-specific effect were investigated by means of a covert orienting paradigm incorporating pictures that were either disgust-evoking, fear-evoking, happiness-evoking or neutral. Attention adhesion to these pictures was measured by the time necessary to identify a peripheral target, presented 100, 200, 500, or 800 ms after picture onset. Main results showed that reaction times were delayed for targets following the disgust-evoking pictures by 100 and 200 ms, suggesting that only these pictures temporarily grabbed hold of participants' attention. These delays were similar for ignore- and attend-instructions, and they were not affected by the participants' anxiety levels or disgust sensitivity. The disgust-specific influence on early attention processes thus appeared very robust, occurring in the majority of participants and without contribution of voluntary- and strategic-attention processes. In contrast, a smaller and less reliable effect of all emotional (arousing) pictures was present in the form of delayed responding in the 100 ms cue-target interval. This effect was more transitory and apparent only in participants with relatively high state-anxiety scores. Practical and theoretical consequences of these findings are discussed.

Testing the snake-detection hypothesis: larger early posterior negativity in humans to pictures of snakes than to pictures of other reptiles, spiders and slugs

According to the snake detection hypothesis (Isbell, 2006), fear specifically of snakes may have pushed evolutionary changes in the primate visual system allowing pre-attentional visual detection of fearful stimuli. A previous study demonstrated that snake pictures, when compared to spiders or bird pictures, draw more early attention as reflected by larger early posterior negativity (EPN). Here we report two studies that further tested the snake detection hypothesis. In Study 1, we tested whether the enlarged EPN is specific for snakes or also generalizes to other reptiles. Twenty-four healthy, non-phobic women watched the random rapid serial presentation of snake, crocodile, and turtle pictures. The EPN was scored as the mean activity at occipital electrodes (PO3, O1, Oz, PO4, O2) in the 225-300 ms time window after picture onset. The EPN was significantly larger for snake pictures than for pictures of the other reptiles. In Study 2, we tested whether disgust plays a role in the modulation of the EPN and whether preferential processing of snakes also can be found in men. 12 men and 12 women watched snake, spider, and slug pictures. Both men and women exhibited the largest EPN amplitudes to snake pictures, intermediate amplitudes to spider pictures and the smallest amplitudes to slug pictures. Disgust ratings were not associated with EPN amplitudes. The results replicate previous findings and suggest that ancestral priorities modulate the early capture of visual attention.

Disgust- and not fear-evoking images hold our attention

Even though disgust and fear are both negative emotions, they are characterized by different physiology and action tendencies. The aim of this study was to examine whether fear- and disgust-evoking images would produce different attention bias effects, specifically those related to attention (dis)engagement. Participants were asked to identify a target which was briefly presented around a central image cue, which could either be disgusting, frightening, or neutral. The interval between cue onset and target presentation varied within blocks (200, 500, 800, 1100 ms), allowing us to investigate the time course of attention engagement. Accuracy was lower and reaction times were longer when targets quickly (200 ms) followed disgust-evoking images than when they followed neutral- or fear-evoking images. For the other, longer interval conditions no significant image effects were found. These results suggest that emotion-specific attention effects can be found at very early visual processing stages and that only disgust-evoking images, and not fear-evoking ones, keep hold of our attention for longer. We speculate that this increase in early attention allocation is related to the need to perform a more comprehensive risk-assessment of the disgust-evoking images. The outcomes underline not only the importance of examining the time course of emotion induced attention effects but also the need to look beyond the dimensions of valence and arousal.

Danger and usefulness are detected early in auditory lexical processing: evidence from electroencephalography

Visual emotionally charged stimuli have been shown to elicit early electrophysiological responses (e.g., Ihssen, Heim, & Keil, 2007; Schupp, Junghöfer, Weike, & Hamm, 2003; Stolarova, Keil, & Moratti, 2006). We presented isolated words to listeners, and observed, using generalized additive modeling, oscillations in the upper part of the delta range, the theta range (Bastiaansen & Hagoort, 2003), and the lower part of the alpha range related to degree of (rated) danger and usefulness (Wurm, 2007) starting around 150 ms and continuing to 350 ms post stimulus onset. A negative deflection in the oscillations tied to danger around 250-300 ms fits well with a similar negativity observed in the same time interval for visual emotion processing. Frequency and competitor effects emerged or reached maximal amplitude later, around or following the uniqueness point. The early effect of danger, long before the words' uniqueness points, is interpreted as evidence for the dual pathway theory of LeDoux (1996).

Exogenous attention to facial vs non-facial emotional visual stimuli

The capacity of the two types of non-symbolic emotional stimuli most widely used in research on affective processes, faces and (non-facial) emotional scenes, to capture exogenous attention, was compared. Negative, positive and neutral faces and affective scenes were presented as distracters to 34 participants while they carried out a demanding digit categorization task. Behavioral (reaction times and number of errors) and electrophysiological (event-related potentials-ERPs) indices of exogenous attention were analyzed. Globally, facial expressions and emotional scenes showed similar capabilities to attract exogenous attention. Electrophysiologically, attentional capture was reflected in the P2a component of ERPs at the scalp level, and in left precentral areas at the source level. Negatively charged faces and scenes elicited maximal P2a/precentral gyrus activity. In the case of scenes, this negativity bias was also evident at the behavioral level. Additionally, a specific effect of facial distracters was observed in N170 at the scalp level, and in the fusiform gyrus and inferior parietal lobule at the source level. This effect revealed maximal attention to positive expressions. This facial positivity offset was also observed at the behavioral level. Taken together, the present results indicate that faces and non-facial scenes elicit partially different and, to some extent, complementary exogenous attention mechanisms.