Processing of unattended emotional visual scenes.

Prime pictures of emotional scenes appeared in parafoveal vision, followed by probe pictures either congruent or incongruent in affective valence. Participants responded whether the probe was pleasant or unpleasant (or whether it portrayed people or animals). Shorter latencies for congruent than for incongruent prime-probe pairs revealed affective priming. This occurred even when visual attention was focused on a concurrent verbal task and when foveal gaze-contingent masking prevented overt attention to the primes but only if these had been preexposed and appeared in the left visual field. The preexposure and laterality patterns were different for affective priming and semantic category priming. Affective priming was independent of the nature of the task (i.e., affective or category judgment), whereas semantic priming was not. The authors conclude that affective processing occurs without overt attention--although it is dependent on resources available for covert attention--and that prior experience of the stimulus is required and right-hemisphere dominance is involved.

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title: Effects of Attention and Emotion on Face Processing in the Human Brain An Event-Related fMRI Study
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title: Additive effects of emotional content and spatial selective attention on electrocortical facilitation.
abstract: Affectively arousing visual stimuli have been suggested to automatically attract attentional resources in order to optimize sensory processing. The present study crosses the factors of spatial selective attention and affective content, and examines the relationship between instructed (spatial) and automatic attention to affective stimuli. In addition to response times and error rate, electroencephalographic data from 129 electrodes were recorded during a covert spatial attention task. This task required silent counting of random-dot targets embedded in a 10 Hz flicker of colored pictures presented to both hemifields. Steady-state visual evoked potentials (ssVEPs) were obtained to determine amplitude and phase of electrocortical responses to pictures. An increase of ssVEP amplitude was observed as an additive function of spatial attention and emotional content. Statistical parametric mapping of this effect indicated occipito-temporal and parietal cortex activation contralateral to the attended visual hemifield in ssVEP amplitude modulation. This difference was most pronounced during selection of the left visual hemifield, at right temporal electrodes. In line with this finding, phase information revealed accelerated processing of aversive arousing, compared to affectively neutral pictures. The data suggest that affective stimulus properties modulate the spatiotemporal process along the ventral stream, encompassing amplitude amplification and timing changes of posterior and temporal cortex.

title: Gaze Patterns When Looking at Emotional Pictures: Motivationally Biased Attention
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title: Eye movement assessment of selective attentional capture by emotional pictures.
abstract: The eye-tracking method was used to assess attentional orienting to and engagement on emotional visual scenes. In Experiment 1, unpleasant, neutral, or pleasant target pictures were presented simultaneously with neutral control pictures in peripheral vision under instruction to compare pleasantness of the pictures. The probability of first fixating an emotional picture, and the frequency of subsequent fixations, were greater than those for neutral pictures. In Experiment 2, participants were instructed to avoid looking at the emotional pictures, but these were still more likely to be fixated first and gazed longer during the first-pass viewing than neutral pictures. Low-level visual features cannot explain the results. It is concluded that overt visual attention is captured by both unpleasant and pleasant emotional content.

title: From searching for features to searching for threat: Drawing the boundary between preattentive and attentive vision
abstract: The distinction between preattentive and attentional processing has been a key element in many theories of attention, but there are conflicting claims as to which functions are performed preattentively, and which require attention. Recent studies suggest that stimuli associated with strong emotions or threat are effective at capturing and/or holding attention. Especially relevant for the question of preattentive vision are search experiments showing that emotional stimuli are sometimes found more quickly than neutral stimuli. An examination of these experiments indicates that there is no evidence that the threatening nature of stimuli is detected preattentively. There is evidence, however, that participants can learn to associate particular features, combinations of features, or configurations of lines with threat, and use them to guide search to threat-related targets. This debate highlights the importance of determining not only what information is encoded preattentively, but how target features that are used to guide search are specified.

title: Semantic Processing Precedes Affect Retrieval: The Neurological Case for Cognitive Primacy in Visual Processing
abstract: According to the affective primacy hypothesis, visual stimuli can be evaluated prior to and independent of object identification and semantic analysis (Zajonc, 1980, 2000). Our review concludes that the affective primacy hypothesis is, from the available evidence, not likely correct. Although people can react to objects that they cannot consciously identify, such affective reactions are dependent upon prior semantic analysis within the visual cortex. The authors propose that the features of objects must first be integrated, and then the objects themselves must be categorized and identified, all prior to affective analysis. Additionally, the authors offer a preliminary neurological analysis of the mere exposure and affective priming effects that is consistent with the claim that semantic analysis is needed to elicit these effects. In sum, the authors conclude that the brain must know what something is in order to know whether it is good or bad.

title: Affective priming with liked and disliked persons: Prime visibility determines congruency and incongruency effects
abstract: The present research investigated whether the affective priming paradigm from Fazio, Sanbonmatsu, Powell, and Kardes (1986) can be used as an implicit measure of person schemata. Names and faces of friends or romantic partners and of a disliked person were used as primes. It was explored whether: (1) stimuli relating to liked and disliked persons elicit congruency priming effects similar to those reported for words; (2) masked and unmasked priming procedures had similar effects; and (3) whether individual differences in the implicit measure were related to explicit measures of relationship quality. For clearly visible primes the expected congruence priming effects were found across names and faces. For marginally visible primes, however, unexpected reverse priming effects were observed for the disliked person. In a second experiment, a confound of the familiarity and evaluation of the significant other primes was removed. Now a reverse priming effect could be demonstrated for masked primes in both liked and disliked person conditions. On the group level, effects were consistent across name and face primes, thus providing strong evidence that priming effects were caused by the activation of person schemata. The reliability of inter-individual differences in person-specific priming effects was found to be unsatisfactory, and correlations with explicit measures were not consistent across name and face priming conditions. An explanation of reverse priming effects is discussed, and measures to improve the psychometric quality of individual affective priming indices are suggested.

title: Emotional conditioning to masked stimuli: expectancies for aversive outcomes following nonrecognized fear-relevant stimuli.
abstract: The role of conscious awareness in human Pavlovian conditioning was examined in 2 experiments using masked fear-relevant (snakes and spiders; Experiments 1 and 2) and fear-irrelevant (flowers and mushrooms; Experiment 1) pictures as conditioned stimuli, a mild electric shock as the unconditioned stimulus, and skin conductance responses as the primary dependent variable. The conditioned stimuli were presented briefly (30 ms) and were effectively masked by an immediately following masking stimulus. Experiment 1 demonstrated nonconscious conditioning to fear-relevant but not to fear-irrelevant stimuli. Even though the participants could not recognize the stimuli in Experiment 2, they differentiated between masked stimuli predicting and not predicting shocks in expectancy ratings. However, expectancy ratings were not related to the conditioned autonomic response.

title: The affective priming effect: Automatic activation of evaluative information in memory.
abstract: Fazio, Sanbonmatsu, Powell, and Kardes (1986) argued that affect may be activated automatically from memory on the mere observation of an affect-loaded stimulus. Using a variant of the standard sequential priming paradigm, it was demonstrated that the time needed to evaluate target words as positive or negative decreased if they were preceded by a similarly valenced prime word, but increased when preceded by a prime of opposite valence. Several aspects of their procedure, however, do not warrant their conclusion concerning the unconditionality of the effect. The present research investigated the generality of this affective priming effect. In Experiment 1, it was tested whether the effect can be generalised to more complex visual material. Stimulus pairs consisted of colour slides. Subjects had to evaluate the targets as quickly as possible. In Experiment 2, the standard word-word procedure was used, but target words had to be pronounced. In both experiments, significant affective priming effects...

title: Are affective events richly recollected or simply familiar? The experience and process of recognizing feelings past.
abstract: The author used the remember/know paradigm and the dual process recognition model of A. P. Yonelinas, N. E. A. Kroll, I. Dobbins, M. Lazzara, and R. T. Knight (1998) to study the states of awareness accompanying recognition of affective images and the processes of recollection and familiarity that may underlie them. Results from all experiments showed that (a) negative stimuli tended to be remembered, whereas positive stimuli tended to be known; (b) recollection, but not familiarity, was boosted for negative or highly arousing and, to a lesser extent, positive stimuli; and (c) across experiments, variations in depth of encoding did not influence these patterns. These data suggest that greater recollection for affective events leads them to be more richly experienced in memory, and they are consistent with the idea that the states of remembering and knowing are experientially exclusive, whereas the processes underlying them are functionally independent.

title: Spatial frequency, phase, and the contrast of natural images.
abstract: We examined contrast sensitivity and suprathreshold apparent contrast with natural images. The spatial-frequency components within single octaves of the images were removed (notch filtered), their phases were randomized, or the polarity of the images was inverted. Of Michelson contrast, root-mean-square (RMS) contrast, and band-limited contrast, RMS contrast was the best index of detectability. Negative images had lower apparent contrast than their positives. Contrast detection thresholds showed spatial-frequency-dependent elevation following both notch filtering and phase randomization. The peak of the spatial-frequency tuning function was approximately 0.5-2 cycles per degree (c/deg). Suprathreshold contrast matching functions also showed spatial-frequency-dependent contrast loss for both notch-filtered and phase-randomized images. The peak of the spatial-frequency tuning function was approximately 1-3 c/deg. There was no detectable difference between the effects of phase randomization and notch filtering on contrast sensitivity. We argue that these observations are consistent with changes in the activity within spatial-frequency channels caused by the higher-order phase structure of natural images that is responsible for the presence of edges and specularities.

title: Contrast in complex images.
abstract: The physical contrast of simple images such as sinusoidal gratings or a single patch of light on a uniform background is well defined and agrees with the perceived contrast, but this is not so for complex images. Most definitions assign a single contrast value to the whole image, but perceived contrast may vary greatly across the image. Human contrast sensitivity is a function of spatial frequency; therefore the spatial frequency content of an image should be considered in the definition of contrast. In this paper a definition of local band-limited contrast in images is proposed that assigns a contrast value to every point in the image as a function of the spatial frequency band. For each frequency band, the contrast is defined as the ratio of the bandpass-filtered image at the frequency to the low-pass image filtered to an octave below the same frequency (local luminance mean). This definition raises important implications regarding the perception of contrast in complex images and is helpful in understanding the effects of image-processing algorithms on the perceived contrast. A pyramidal image-contrast structure based on this definition is useful in simulating nonlinear, threshold characteristics of spatial vision in both normal observers and the visually impaired.

title: Preferences and Inferences in Encoding Visual Objects: A Systematic Comparison of Semantic and Affective Priming
abstract: The authors systematically compared semantic and affective priming in five studies involving words and pictures. In Studies 1 (lexical decision task) and 2 (evaluation task), irrelevant short duration (200 ms) primes were briefly flashed before relevant targets. The authors orthogonally varied both the semantic and affective relations between primes and targets. In both studies, semantic priming but not affective priming was found. Study 3 revealed that the same stimuli can produce affective priming, but only when words come from a single semantic category. Studies 4 and 5 used pictures rather than words to examine automatic encoding tendencies. The results conceptually replicated those from Studies 1 and 2. In sum, the findings suggest that affective priming may be a relatively fragile phenomenon, particularly when the semantic properties of objects vary in a salient manner.

title: Identification facilitation for emotionally arousing verbs during the attentional blink.
abstract: The present study aimed to examine affective modulation of the "attentional blink" effect during rapid serial visual presentation (RSVP). Pleasant, neutral, and unpleasant written verbs were used as a 2nd target (T2) in an 8.6-Hz RSVP paradigm. Pronounced effects of 1st target (T1)-T2 stimulus onset asynchrony (SOA) were found, showing reduced report accuracy for 232- and 464-ms SOAs. Affectively arousing (pleasant and unpleasant) T2s were associated with enhanced accuracy compared with neutral T2s specifically during short (232 ms) SOAs. In contrast, pleasant and unpleasant T2s rated low in terms of emotional arousal did not show this enhancement. These results suggest that affectively arousing information is selected preferentially from a temporal stream, facilitating processes such as working memory consolidation and action.

title: Attentional interference effects of emotional pictures: threat, negativity, or arousal?
abstract: Attentional interference arising from emotional pictures was examined. Participants had to ignore emotional pictures while solving math problems (Study 1, N = 126) or detecting the location of a line (Study 2, N = 60). Data analyses tested predictions of 3 theories. Evolutionary threat theory predicts interference by snake pictures. Categorical negativity theory predicts interference by negative pictures regardless of their intensity. According to arousal theory, arousal level predicts interference effects. The results supported arousal theory, with the most arousing pictures (strong unpleasant pictures, oppositesex models) producing the strongest interference. The findings are interpreted in the context of process models of emotions that postulate an initial relevance check before further processing of valence and other appraisal dimensions.

title: Automatic non-associative semantic priming: episodic affective priming of naming responses.
abstract: Affective priming for associatively unrelated prime-target pairs was investigated using (a) the naming task, (b) a short stimulus onset asynchrony (250 ms), and (c) primes that had acquired their affective connotation during a differential evaluative conditioning procedure. Despite the fact that the primes and the targets were related on the affective dimension only, significant priming emerged. This finding indicates that mere affective overlap is sufficient to produce automatic priming. As such, our results are in line with theoretical accounts of automatic priming that are based on semantic relatedness.

title: Distracted and confused?: Selective attention under load
abstract: The ability to remain focused on goal-relevant stimuli in the presence of potentially interfering distractors is crucial for any coherent cognitive function. However, simply instructing people to ignore goal-irrelevant stimuli is not sufficient for preventing their processing. Recent research reveals that distractor processing depends critically on the level and type of load involved in the processing of goal-relevant information. Whereas high perceptual load can eliminate distractor processing, high load on "frontal" cognitive control processes increases distractor processing. These findings provide a resolution to the long-standing early and late selection debate within a load theory of attention that accommodates behavioural and neuroimaging data within a framework that integrates attention research with executive function.

title: How brains beware: neural mechanisms of emotional attention
abstract: Emotional processes not only serve to record the value of sensory events, but also to elicit adaptive responses and modify perception. Recent research using functional brain imaging in human subjects has begun to reveal neural substrates by which sensory processing and attention can be modulated by the affective significance of stimuli. The amygdala plays a crucial role in providing both direct and indirect top-down signals on sensory pathways, which can influence the representation of emotional events, especially when related to threat. These modulatory effects implement specialized mechanisms of 'emotional attention' that might supplement but also compete with other sources of top-down control on perception. This work should help to elucidate the neural processes and temporal dynamics governing the integration of cognitive and affective influences in attention and behaviour.

title: Right hemisphere lateralization for emotion in the human brain: interactions with cognition
abstract: Right-handed subjects tend to look to the left when answering affective questions. The relative shift in gaze from right to left is accentuated when the questions also involve spatial manipulation and attenuated when the questions require verbal manipulation. The data support the hypothesis that the right hemisphere has a special role in emotion in the intact brain, and that predictable patterning of hemispheric activity can occur when specific combinations of cognitive and affective processes interact.

title: Cortical Systems for the Recognition of Emotion in Facial Expressions
abstract: This study is part of an effort to map neural systems involved in the processing of emotion, and it focuses on the possible cortical components of the process of recognizing facial expressions. We hypothesized that the cortical systems most responsible for the recognition of emotional facial expressions would draw on discrete regions of right higher-order sensory cortices and that the recognition of specific emotions would depend on partially distinct system subsets of such cortical regions. We tested these hypotheses using lesion analysis in 37 subjects with focal brain damage. Subjects were asked to recognize facial expressions of six basic emotions: happiness, surprise, fear, anger, disgust, and sadness. Data were analyzed with a novel technique, based on three-dimensional reconstruction of brain images, in which anatomical description of surface lesions and task performance scores were jointly mapped onto a standard brain-space. We found that all subjects recognized happy expressions normally but that some subjects were impaired in recognizing negative emotions, especially fear and sadness. The cortical surface regions that best correlated with impaired recognition of emotion were in the right inferior parietal cortex and in the right mesial anterior infracalcarine cortex. We did not find impairments in recognizing any emotion in subjects with lesions restricted to the left hemisphere. These data provide evidence for a neural system important to processing facial expressions of some emotions, involving discrete visual and somatosensory cortical sectors in right hemisphere.

title: Right hemisphere emotional perception: evidence across multiple channels.
abstract: Emotional perception was examined in stroke patients across 3 communication channels: facial, prosodic, and lexical. Hemispheric specialization for emotion was tested via right-hemisphere (RH) and valence hypotheses, and relationships among channels were determined. Participants were 11 right-brain-damaged (RBD), 10 left-brain-damaged (LBD), and 15 demographically matched normal control (NC) adults. Experimental measures, with analogous psychometric properties, were identification and discrimination tasks, including a range of positive and negative emotions. Nonemotional control tasks were used for each channel. For identification, RBDs were significantly impaired relative to LBDs and NCs across channels and valences, supporting the RH hypothesis. No group differences emerged for discrimination. Findings were not influenced by demographic, clinical, or control variables. Correlations among the channels were more prominent for normal than for brain-damaged groups.

title: Functional neuroanatomy of emotions: A meta-analysis
abstract: The application of functional neuroimaging to the study of human emotion has yielded valuable data; however, the conclusions that may be drawn from any one study are limited. We applied novel statistical techniques to the meta-analysis of 106 PET and fMRI studies of human emotion and tested predictions made by key neuroscientific models. The results demonstrated partial support for asymmetry accounts. Greater left-sided activity was observed for approach emotions, whereas neural activity associated with negative/withdrawal emotions was symmetrical. Support was also found for affect program emotion accounts. The activation distributions associated with fear, disgust, and anger differed significantly. These emotions were most consistently associated in activity in regions associated with selective processing deficits when damaged: the amygdala, the insula and globus pallidus, and the lateral orbitofrontal cortex, respectively. In contrast, the distributions for happiness and sadness did not differ. These findings are considered in the context of conceptualizations of the neural correlates of human emotion.

title: Emotional arousal and activation of the visual cortex: an fMRI analysis.
abstract: Functional activity in the visual cortex was assessed using functional magnetic resonance imaging technology while participants viewed a series of pleasant, neutral, or unpleasant pictures. Coronal images at four different locations in the occipital cortex were acquired during each of eight 12-s picture presentation periods (on) and 12-s interpicture interval (off). The extent of functional activation was larger in the right than the left hemisphere and larger in the occipital than in the occipitoparietal regions during processing of all picture contents compared with the interpicture intervals. More importantly, functional activity was significantly greater in all sampled brain regions when processing emotional (pleasant or unpleasant) pictures than when processing neutral stimuli. In Experiment 2, a hypothesis that these differences were an artifact of differential eye movements was ruled out. Whereas both emotional and neutral pictures produced activity centered on the calcarine fissure (Area 17), only emotional pictures also produced sizable clusters bilaterally in the occipital gyrus, in the right fusiform gyrus, and in the right inferior and superior parietal lobules.

title: Activation of the visual cortex in motivated attention.
abstract: Functional activation (measured with fMRI) in occipital cortex was more extensive when participants view pictures strongly related to primary motive states (i.e., victims of violent death, viewer-directed threat, and erotica). This functional activity was greater than that observed for less intense emotional (i.e., happy families or angry faces) or neutral images (i.e., household objects, neutral faces). Both the extent and strength of functional activity were related to the judged affective arousal of the different picture contents, and the same pattern of functional activation was present whether pictures were presented in color or in grayscale. It is suggested that more extensive visual system activation reflects "motivated attention," in which appetitive or defensive motivational engagement directs attention and facilitates perceptual processing of survival-relevant stimuli.

title: Common effects of emotional valence, arousal and attention on neural activation during visual processing of pictures
abstract: Emotion and attention heighten sensitivity to visual cues. How neural activation patterns associated with emotion change as a function of the availability of attentional resources is unknown. We used positron emission tomography (PET) and 15O-water to measure brain activity in male volunteers while they viewed emotional picture sets that could be classified according to valence or arousal. Subjects simultaneously performed a distraction task that manipulated the availability of attentional resources. Twelve scan conditions were generated in a 3 x 2 x 2 factorial design involving three levels of valence (pleasant, unpleasant and neutral), two levels of arousal and two levels of attention (low and high distraction). Extrastriate visual cortical and anterior temporal areas were independently activated by emotional valence, arousal and attention. Common areas of activation derived from a conjunction analysis of these separate activations revealed extensive areas of activation in extrastriate visual cortex with a focus in right BA18 (12, -88, -2) (Z=5.73, P < 0.001 corrected) and right anterior temporal cortex BA38 (42, 14, -30) (Z=4.03, P < 0.05 corrected). These findings support an hypothesis that emotion and attention modulate both early and late stages of visual processing.

title: The involvement of distinct visual channels in rapid attention towards fearful facial expressions
abstract: This paper reports five experiments demonstrating that the low spatial frequency components of faces are critical to the production of rapid attentional responses towards fearful facial expressions. In our main experiments, low spatial frequency (LSF) or high spatial frequency (HSF) face pairs, consisting of one fearful and one neutral expression, were presented on a computer screen for a brief period. Participants were required to identify as quickly as possible the orientation of a bar target that immediately replaced one of the faces. Responses were faster when targets replaced the location of LSF fearful faces, compared with LSF neutral faces. By contrast, there were no differences between responses to targets replacing HSF fearful versus HSF neutral faces. This facilitation in spatial orienting occurred specifically with short time intervals between faces and target, and is consistent with a rapid processing of fear cues from LSF inputs that can serve to guide attention towards threat events.

title: Processing of “unattended” threat-related information: Role of emotional content and context
abstract: Unpleasant, pleasant, or neutral visual scenes served as a context for the presentation of threat-related, positive, and neutral words. On each trial, 2 simultaneous prime words (one foveal, i.e., at fixation, and one parafoveal, i.e., 2.2° apart) appeared for 150 ms, followed by a foveally presented probe word in a lexical decision task. Results showed facilitation in response times for probe threat words when primed by an identical parafoveal word, in comparison with priming by an unrelated parafoveal word, and this effect was enhanced in an emotionally congruent unpleasant context. In contrast, no parafoveal effect appeared for positive words, even in a pleasant context. This reveals parallel processing of threat-related words outside the focus of attention.

title: Is emotional content obtained from parafoveal words during reading? An eye movement analysis.
abstract: An eye-movement-contingent display change technique was employed to study whether adult readers extract semantic information from parafoveal words during reading. Three types of parafoveal preview conditions were contrasted: an emotional word, a neutral word, and an identical word condition. To have a maximally effective parafoveal manipulation, high-arousal emotional words (sex- and threat-related and curse words) were used as parafoveal previews. Readers' eye fixation patterns around the target word revealed no evidence for parafoveal semantic processing. Furthermore, the pupil size showed no signs for an emotional response triggered by an emotional word previewed parafoveally. These results are consistent with the view that, as a rule, only the fixated word is processed to a semantic level during reading.

title: Word frequency and laterality effects in lexical decision: Right hemisphere mechanisms
abstract: Three experiments investigated the role of the right cerebral hemisphere in the word frequency effect observed in visual word recognition. The experiments examined lexical decisions to low and high frequency words as well as non-words in a divided visual field paradigm. Experiment 1 showed a significant word frequency effect only for left visual field presentation. Experiment 2 provided a partial replication of the results of Experiment 1 with a different set of words. In Experiment 3, case alternation was implemented to investigate a possible explanation of the findings. Results of the first experiment were replicated in the condition without case alternation. In the case-alternated condition, the word frequency effect was significant only for right visual field presentations. The present findings emphasize the need to consider that information processing strategies relevant to hemispheric asymmetries might account in part for the word frequency effect.

title: The face in the crowd revisited: a threat advantage with schematic stimuli.
abstract: Schematic threatening, friendly, and neutral faces were used to test the hypothesis that humans preferentially orient their attention toward threat. Using a visual search paradigm, participants searched for discrepant faces in matrices of otherwise identical faces. Across 5 experiments, results consistently showed faster and more accurate detection of threatening than friendly targets. The threat advantage was obvious regardless of whether the conditions favored parallel or serial search (i.e., involved neutral or emotional distractors), and it was valid for inverted faces. Threatening angry faces were more quickly and accurately detected than were other negative faces (sad or "scheming"), which suggests that the threat advantage can be attributed to threat rather than to the negative valence or the uniqueness of the target display.

title: Emotional facial expressions capture attention
abstract: To determine whether the emotional significance of stimuli can influence spatial attention.  Motivational and emotional factors may affect attention toward stimuli. However, this has never been examined in brain-damaged patients who present with unilateral inattention due to left spatial neglect.  The authors studied three patients with chronic left neglect and visual extinction after right parietal stroke. Shapes or faces with neutral, happy, or angry expressions were briefly presented in the right, left, or both visual fields. On unilateral trials, the patients detected all stimuli equally on both sides. On bilateral trials, they extinguished faces in the contralesional field much less often than shapes, and faces with happy or angry facial expressions much less than faces with a neutral expression.  Facial features and emotional expressions can be analyzed despite lying on the unattended side, and may influence the spatial distribution of attention. These findings support the view that attention is controlled by neural mechanisms involving not only frontoparietal areas but also limbic components in cingulate cortex and amygdala, which may interact with ventral visual areas in the temporal lobe to detect affective value and prioritize attention to salient stimuli.

title: Neural processing of emotional faces requires attention
abstract: Attention gates the processing of stimuli relatively early in visual cortex. Yet, existing data suggest that emotional stimuli activate brain regions automatically, largely immune from attentional control. To resolve this puzzle, we used functional magnetic resonance imaging to first measure activation in regions that responded differentially to faces with emotional expressions (fearful and happy) compared with neutral faces. We then measured the modulation of these responses by attention, using a competing task with a high attentional load. Contrary to the prevailing view, all brain regions responding differentially to emotional faces, including the amygdala, did so only when sufficient attentional resources were available to process the faces. Thus, the processing of facial expression appears to be under top-down control.

title: The role of spatial attention in the processing of facial expression: An ERP study of rapid brain responses to six basic emotions
abstract: To investigate the time course of emotional expression processing, we recorded ERP responses to stimulus arrays containing neutral versus angry, disgusted, fearful, happy, sad, or surprised faces. In one half of the experiment, the task was to discriminate emotional and neutral facial expressions. Here, an enhanced early frontocentral positivity was elicited in response to emotional as opposed to neutral faces, followed by a broadly distributed positivity and an enhanced negativity at lateral posterior sites. These emotional expression effects were very similar for all six basic emotional expressions. In the other half of the experiment, attention was directed away from the faces toward a demanding perceptual discrimination task. Under these conditions, emotional expression effects were completely eliminated, demonstrating that brain processes involved in the detection and analysis of facial expression require focal attention. The face-specific N170 component was unaffected by any emotional expression, supporting the hypothesis that structural encoding and expression analysis are independent processes.