Interference produced by emotional conflict associated with anterior cingulate activation

The anterior cingulate cortex (ACC) is involved in cognition and emotion. In the classic Stroop task, presentation of stimuli that are in response conflict with one another produces activation in the caudal ACC. In the emotional Stroop task, presentation of emotionally salient stimuli produces activation in the rostral ACC. Presentation of stimuli that are emotionally conflicting should activate the caudal ACC; stimuli that are emotionally salient should activate the rostral ACC. We tested this prediction using functional magnetic resonance imaging while subjects made emotional valence judgments of words overlaid on emotional faces (word-face Stroop task). Emotionally incongruent pairs were responded to more slowly than emotionally congruent pairs. Emotionally incongruent trials were associated with increased activation within the caudal ACC, whereas no ACC activation was found in response to emotional saliency. These results support the conflict-monitoring model of caudal ACC and extend this function to conflict within the domain of emotional stimuli.     

Integration of faces and voices, but not faces and names, in person recognition

Recent studies on cross-modal recognition suggest that face and voice information are linked for the purpose of person identification. We tested whether congruent associations between familiarized faces and voices facilitated subsequent person recognition relative to incongruent associations. Furthermore, we investigated whether congruent face and name associations would similarly benefit person identification relative to incongruent face and name associations. Participants were familiarized with a set of talking video-images of actors, their names, and their voices. They were then tested on their recognition of either the face, voice, or name of each actor from bimodal stimuli which were either congruent or novel (incongruent) associations between the familiarized face and voice or face and name. We found that response times to familiarity decisions based on congruent face and voice stimuli were facilitated relative to incongruent associations. In contrast, we failed to find a benefit for congruent face and name pairs. Our findings suggest that faces and voices, but not faces and names, are integrated in memory for the purpose of person recognition. These findings have important implications for current models of face perception and support growing evidence for multisensory effects in face perception areas of the brain for the purpose of person recognition.     

Speech perception and vocal expression of emotion

Two experiments using identical stimuli were run to determine whether the vocal expression of emotion affects the speed with which listeners can identify emotion words. Sentences were spoken in an emotional tone of voice (Happy, Disgusted, or Petrified), or in a Neutral tone of voice. Participants made speeded lexical decisions about the word or pseudoword in sentence-final position. Critical stimuli were emotion words that were either semantically congruent or incongruent with the tone of voice of the sentence. Experiment 1, with randomised presentation of tone of voice, showed no effect of congruence or incongruence. Experiment 2, with blocked presentation of tone of voice, did show such effects: Reaction times for congruent trials were faster than those for baseline trials and incongruent trials. Results are discussed in terms of expectation (e.g., Kitayama, 1990, 1991, 1996) and emotional connotation, and implications for models of word recognition are considered.     

Metamemory for faces, names, and common nouns

This study examined the metacognitive aspects of face–name learning with the goal of providing a comprehensive profile of monitoring performance during this task. Four types of monitoring judgments were solicited during encoding and retrieval of novel face–name associations. Across all of the monitoring judgments, relative accuracy was significantly above chance for face and name targets. Furthermore, metamemory performance was similar between both target conditions, even though names were more difficult to recognize than faces. As a preliminary test of the stability of monitoring accuracy across different categories of stimuli, we also compared metamemory performance between face–name pairs and noun–noun pairs. Prospective monitoring accuracy was similar across the categories of stimuli, but retrospective monitoring accuracy was superior for noun targets compared with face or name targets. Altogether, our results indicate that participants can monitor their memory for face–name associations at a level above chance, and retrospective monitoring is more accurate with nouns compared with faces and names.     

Exploring emotional and cognitive conflict using speeded voluntary facial expressions

Affective conflict and control may have important parallels to cognitive conflict and control, but these processes have been difficult to quantitatively study with emotionally naturalistic laboratory paradigms. The current study examines a modification of the AX-Continuous Performance Task (AX-CPT), a well-validated probe of cognitive conflict and control, for the study of emotional conflict. In the Emotional AX-CPT, speeded emotional facial expressions measured with electromyography (EMG) were used as the primary response modality, and index of emotional conflict. Bottom-up emotional conflict occurred on trials in which precued facial expressions were incongruent with the valence of an emotionally evocative picture probe (e.g., smiling to a negative picture). A second form of top-down conflict occurred in which the facial expression and picture probe were congruent, but the opposite expression was expected based on the precue. A matched version of the task was also performed (in a separate group of participants) with affectively neutral probe stimuli. Behavioral interference was observed, in terms of response latencies and errors, on all conflict trials. However, bottom-up conflict was stronger in the emotional version of the task compared to the neutral version; top-down conflict was similar across the two versions. The results suggest that voluntary facial expressions may be more sensitive to indexing emotional than nonemotional conflict, and importantly, may provide an ecologically valid method of examining how emotional conflict may manifest in behavior and brain activity.     

面孔表情和声音情绪信息整合对返回抑制的影响

返回抑制(inhibition of return, IOR)与情绪刺激都具有引导注意偏向、提高搜索效率的特点, 但二者间是否存在一定的交互作用迄今为止尚不明确。研究采用“线索-目标”范式并在视听双通道呈现情绪刺激来考察情绪刺激的加工与IOR的交互作用。实验1中情绪刺激以单通道视觉面孔或一致的视听双通道呈现, 实验2通过在视听通道呈现不一致的情绪刺激进一步考察视听双通道情绪一致刺激对IOR的影响是否是由听觉通道一致的情绪刺激导致的, 即是否对听觉通道的情绪刺激进行了加工。结果发现, 视听双通道情绪一致刺激能够削弱IOR, 但情绪不一致刺激与IOR之间不存在交互作用, 并且单双通道的IOR不存在显著差异。研究结果表明仅在视听双通道呈现情绪一致刺激时, 才会影响同一阶段的IOR, 这进一步支持了IOR的知觉抑制理论。     

Attentional control adjustments in Eriksen and Stroop task performance can be independent of response conflict

In the Eriksen flanker and colour-word Stroop tasks, the response time (RT) difference between incongruent and congruent trials is smaller following incongruent trials than following congruent trials: the “Gratton effect” (Gratton, Coles, & Donchin, 1992). According to the prevailing conflict-monitoring theory (Botvinick, Braver, Barch, Carter, & Cohen, 2001), the Gratton effect reflects attentional control adjustment following response conflict on incongruent trials. However, because previous studies compared incongruent and congruent trials, it remains unclear to what extent the Gratton effect is driven by incongruent rather than congruent trials. To resolve this issue, we included neutral trials in addition to incongruent and congruent trials in the Eriksen (Experiment 1) and Stroop (Experiment 2) tasks. Participants responded manually and vocally in both tasks. Moreover, we assessed responding to Stroop stimuli that were preceded by neutral cues or by incongruent- or congruent-predicting cues (Experiment 3). In all three experiments, the RT difference between incongruent and congruent trials was larger for postcongruent trials than for postincongruent and postneutral trials. These findings suggest that control adjustments can be independent of response conflict, challenging conflict-monitoring theory.     

Crossmodal integration of emotional information from face and voice in the infant brain

We examined 7-month-old infants' processing of emotionally congruent and incongruent face-voice pairs using ERP measures. Infants watched facial expressions (happy or angry) and, after a delay of 400 ms, heard a word spoken with a prosody that was either emotionally congruent or incongruent with the face being presented. The ERP data revealed that the amplitude of a negative component and a subsequent positive component in infants' ERPs varied as a function of crossmodal emotional congruity. An emotionally incongruent prosody elicited a larger negative component in infants' ERPs than did an emotionally congruent prosody. Conversely, the amplitude of infants' positive component was larger to emotionally congruent than to incongruent prosody. Previous work has shown that an attenuation of the negative component and an enhancement of the later positive component in infants' ERPs reflect the recognition of an item. Thus, the current findings suggest that 7-month-olds integrate emotional information across modalities and recognize common affect in the face and voice.     

Attentional control adjustments in Eriksen and Stroop task performance can be independent of response conflict

In the Eriksen flanker and colour-word Stroop tasks, the response time (RT) difference between incongruent and congruent trials is smaller following incongruent trials than following congruent trials: the "Gratton effect" (Gratton, Coles, & Donchin, 1992). According to the prevailing conflict-monitoring theory (Botvinick, Braver, Barch, Carter, & Cohen, 2001), the Gratton effect reflects attentional control adjustment following response conflict on incongruent trials. However, because previous studies compared incongruent and congruent trials, it remains unclear to what extent the Gratton effect is driven by incongruent rather than congruent trials. To resolve this issue, we included neutral trials in addition to incongruent and congruent trials in the Eriksen (Experiment 1) and Stroop (Experiment 2) tasks. Participants responded manually and vocally in both tasks. Moreover, we assessed responding to Stroop stimuli that were preceded by neutral cues or by incongruent- or congruent-predicting cues (Experiment 3). In all three experiments, the RT difference between incongruent and congruent trials was larger for postcongruent trials than for postincongruent and postneutral trials. These findings suggest that control adjustments can be independent of response conflict, challenging conflict-monitoring theory.     

Evidence for the integration of audiovisual emotional information at the perceptual level of processing

The present aim was to investigate how emotional expressions presented on an unattended channel affect the recognition of the attended emotional expressions. In Experiments 1 and 2, facial and vocal expressions were simultaneously presented as stimulus combinations. The emotions (happiness, anger, or emotional neutrality) expressed by the face and voice were either congruent or incongruent. Subjects were asked to attend either to the visual (Experiment 1) or auditory (Experiment 2) channel and recognise the emotional expression. The result showed that the ignored emotional expressions significantly affected the processing of attended signals as measured by recognition accuracy and response speed. In general, attended signals were recognised more accurately and faster in congruent than in incongruent combinations. In Experiment 3, possibility for a perceptual-level integration was eliminated by presenting the response-relevant and response-irrelevant signals separated in time. In this situation, emotional information presented on the nonattended channel ceased to affect the processing of emotional signals on the attended channel. The present results are interpreted to provide evidence for the view that facial and vocal emotional signals are integrated at the perceptual level of information processing and not at the later response-selection stages.     

Attention and gaze shifting in dual-task and go/no-go performance with vocal responding

Evidence from go/no-go performance on the Eriksen flanker task with manual responding suggests that individuals gaze at stimuli just as long as needed to identify them (e.g., Sanders, 1998). In contrast, evidence from dual-task performance with vocal responding suggests that gaze shifts occur after response selection (e.g., Roelofs, 2008a). This difference in results may be due to the nature of the task situation (go/no-go vs. dual task) or the response modality (manual vs. vocal). We examined this by having participants vocally respond to congruent and incongruent flanker stimuli and shift gaze to left- or right-pointing arrows. The arrows required a manual response (dual task) or determined whether the vocal response to the flanker stimuli had to be given or not (go/no-go). Vocal response and gaze shift latencies were longer on incongruent than congruent trials in both dual-task and go/no-go performance. The flanker effect was also present in the manual response latencies in dual-task performance. Ex-Gaussian analyses revealed that the flanker effect on the gaze shifts consisted of a shift of the entire latency distribution. These results suggest that gaze shifts occur after response selection in both dual-task and go/no-go performance with vocal responding.     

Emotional facilitation effect in the picture–word interference task: An ERP study

In this paper, we aimed to verify the emotional facilitation effect in the picture–word interference task using event-related potentials. Twenty-one healthy subjects were asked to categorize the emotional valences of pictures accompanied by emotionally congruent, either centrally or laterally positioned Chinese words. For both the foveal and lateral word presentations, the reaction times were faster compared to the picture-only presentation. Compared to the picture-only presentation, P200 amplitude increased under the foveal word presentation condition and decreased under the lateral word presentation condition, indicating that more attentional resources were required when an accompanying word was in the center of a picture than when the word was in the lateral position. Latency of P300 was shorter in response to picture–word stimuli irrespective of word position, indicating that an emotionally congruent word facilitated the emotional processing of the target picture, which verified the emotional facilitation effect and was consistent with the results in psychology. The late positive component was more positive when the picture–word stimuli were more positive, which reflected the feature of positivity offset. The findings suggest that the time window for an emotional facilitation effect may be limited to processing aspects associated with P300 (i.e., affective evaluation).     

Evidence for task conflict in the Stroop effect

C. M. MacLeod and P. A. MacDonald (2000) suggested that congruent and incongruent Stroop stimuli cause more task conflict than neutral stimuli because the anterior cingulate cortex is more activated with these stimuli. This study investigated behavioral expression for this pattern. Experiment 1 reduced task conflict control by increasing the proportion of nonword neutrals. Additionally, half the trials had conflict or neutral cues. The control reduction revealed the task conflict. For noncued trials, response time was longer for congruent stimuli than for neutral stimuli (reverse facilitation effect). In addition, response time for congruent stimuli was longer when stimuli were uncued vs. cued. Experiment 2 increased task conflict control by changing the neutral stimuli to noncolor words. Consequently, the task conflict expression disappeared.     

Explicit vs. implicit emotional processing: The interaction between processing type and executive control

The current study examined whether the interaction between emotion and executive control (EC) is modulated by the processing type of the emotional information. Namely, whether the emotional information is explicitly processed, implicitly processed or passively viewed. In each trial, a negative or neutral picture preceded an arrow-flanker stimulus that was congruent or incongruent. Incongruent stimuli are known to recruit EC. Explicit processing of the pictures (Experiment 1a), which required responding to their emotional content, resulted in emotional interference for congruent but not for incongruent stimuli. Similar effects were shown for the passive viewing condition (Experiment 2). In contrast, implicit processing (Experiment 1b), which required responding to non-emotional content, resulted in emotional interference for both congruent and incongruent stimuli. Thus, our findings indicate that implicit emotional processing affects performance independently of EC recruitment. In contrast, explicit emotional processing and passive viewing of emotional pictures lead to reduced emotional interference when EC is recruited.     

Conflicts as aversive signals

Theories of human action control deal with the question of how cognitive control is dynamically adjusted to task demands. The conflict monitoring theory of anterior cingulate (ACC) function suggests that the ACC monitors for response conflicts in the ongoing processing stream thereby triggering the mobilization of cognitive control. Alternatively, the outcome evaluation account of ACC function suggests that the ACC monitors for negative performance outcomes, an information that serves as an aversive learning signal for future action selection. Botvinick (2007) recently suggested that both theories might converge on the detection of aversive signals in general. Here, the authors provide first evidence that conflicts are registered as aversive signals. Congruent and incongruent Stroop color-words served as primes, and positive and negative stimuli as targets in an affective priming paradigm. Negative targets were evaluated faster after incongruent than after congruent Stroop primes, and positive targets were evaluated slower after incongruent than after congruent primes. The finding that conflicts are actually registered as aversive signals bridges the gap between competing theories of ACC function and has broad theoretical and behavioral implications as it makes the conflict monitoring theory applicable to a much wider range of situations and tasks.     

Positive emotion modulates cognitive control: An event‐related potentials study

There is substantial evidence to indicate that negative emotion can modulate cognitive control processing. However, only a few studies have investigated this effect with positive emotion. Therefore, the present study explored the electrophysiological correlates of the impact of positive emotional stimuli on cognitive control, using event‐related potentials (ERPs). Sixteen healthy young adults completed a modified Simon task (Simon, 1969). Behavioral data indicated that reaction times were faster for positive emotional stimuli than for neutral emotional stimuli in the incongruent condition, but not in the congruent condition, which suggested that positive emotion expedited conflict resolution. The ERP data showed that two negative ERP components (N300–400 and N450–550) were associated with the positive emotional stimuli in the incongruent minus congruent condition. It is suggested that these components may respectively be related to the conflict monitoring (N300–400) and response selection (N450–550) stages of cognitive control processing. Overall, our results indicated that positive emotion could facilitate cognitive control processing. These results are in line with the neuropsychological theory, according to which, positive emotion could modulate cognitive control mediated by increased dopamine levels in frontal brain areas.     

Depth of facial expression processing depends on stimulus visibility: Behavioral and electrophysiological evidence of priming effects

Participants performed a priming task during which emotional faces served as prime stimuli and emotional words served as targets. Prime-target pairs were congruent or incongruent, and two levels of prime visibility were obtained by varying the duration of the masked primes. To probe a neural signature of the impact of the masked primes, lateralized readiness potentials (LRPs) were recorded over motor cortex. In the high-visibility condition, responses to word targets were faster when the prime-target pairs were congruent than when they were incongruent, providing evidence of priming effects. In line with the behavioral results, the electrophysiological data showed that high-visibility face primes resulted in LRP differences between congruent and incongruent trials, suggesting that prime stimuli initiated motor preparation. Contrary to the above pattern, no evidence for reaction time or LRP differences was observed in the low-visibility condition, revealing that the depth of facial expression processing is dependent on stimulus visibility.     

The role of emotional context in facilitating imitative actions

In two experiments, we explored whether emotional context influences imitative action tendencies. To this end, we examined how emotional pictures, presented as primes, affect imitative tendencies using a compatibility paradigm. In Experiment 1, when seen index finger movements (lifting or tapping) and pre-instructed finger movements (tapping) were the same (tapping–tapping, compatible trials), participants were faster than when they were different (lifting–tapping, incompatible trials). This compatibility effect was enhanced when the seen finger movement was preceded by negative primes compared with positive or neutral primes. In Experiment 2, using only negative and neutral primes, the influence of negative primes on the compatibility effect was replicated with participants performing two types of pre-instructed finger movements (tapping and lifting). This emotional modulation of the compatibility effect was independent of the participants' trait anxiety level. Moreover, the emotional modulation pertained primarily to the compatible conditions, suggesting facilitated imitation due to negatively valent primes rather than increased interference. We speculate that negative stimuli increase imitative tendencies as a natural response in potential flight-or-fight situations.     

Multisensory processing in the redundant-target effect: a behavioral and event-related potential study

Participants respond more quickly to two simultaneously presented target stimuli of two different modalities (redundant targets) than would be predicted from their reaction times to the unimodal targets. To examine the neural correlates of this redundant-target effect, event-related potentials (ERPs) were recorded to auditory, visual, and bimodal standard and target stimuli presented at two locations (left and right of central fixation). Bimodal stimuli were combinations of two standards, two targets, or a standard and a target, presented either from the same or from different locations. Responses generally were faster for bimodal stimuli than for unimodal stimuli and were faster for spatially congruent than for spatially incongruent bimodal events. ERPs to spatially congruent and spatially incongruent bimodal stimuli started to differ over the parietal cortex as early as 160 msec after stimulus onset. The present study suggests that hearing and seeing interact at sensory-processing stages by matching spatial information across modalities.     

Negative congruence effects in letter and pseudo-letter recognition: the role of similarity and response conflict

Letters and pseudo-letters were presented in three experiments using a sequential same-different task. While first items were always presented in isolation, the second item was either presented in isolation or surrounded by geometrical non-target shapes that could be congruent or incongruent to the target. In two experiments, a physical sameness criterion was used. In Experiment 1, in one condition, different pairs were always distinct in shape, in another they were similar in shape. Negative congruence effects were obtained for different pairs that are similar. In Experiment 2, this effect is replicated within participants. In this experiment, similar and dissimilar stimuli were mixed. The results were explained in terms of the difficulty of responding different to stimuli that are similar in shape: when the second item is surrounded by a congruent shape, the similarity is emphasized, making this response even more difficult. In Experiment 3, the same stimuli were presented using a categorical sameness criterion. This reduces the role of physical similarity and thus eliminates the response conflict. As a result, negative congruence effects were no longer observed. Taken together, the three experiments identify another source of negative congruence effects besides the ones recently reported in the literature.