Memory for facial expressions in social phobia

Memory biases toward threat have been documented in several anxiety disorders, but contradictory findings have recently been reported in social phobics' recognition of facial expressions. The present study examined recognition memory in clients with social phobia, in an effort to clarify previous inconsistent results. Just before giving a speech to a live audience, social phobia clients and normal controls viewed photographs of people with reassuring and threatening facial expressions. The stimuli were later presented again alongside photographs of the same person with a different facial expression, and participants chose which face they had seen before. Individuals with social phobia were less accurate at recognizing previously seen photographs than controls, apparently due to state anxiety. In contrast, social phobics did not show a memory bias toward threatening facial expressions. Theoretical and treatment implications are discussed.     

Memory bias for emotional facial expressions in major depression

Sixteen clinically depressed patients and sixteen healthy controls were presented with a set of emotional facial expressions and were asked to identify the emotion portrayed by each face. They, were subsequently given a recognition memory test for these faces. There was no difference between the groups in terms of their ability to identify emotion between from faces. All participants identified emotional expressions more accurately than neutral expressions, with happy expressions being identified most accurately. During the recognition memory phase the depressed patients demonstrated superior memory for sad expressions, and inferior memory for happy expressions, relative to neutral expressions. Conversely, the controls demonstrated superior memory for happy expressions, and inferior memory for sad expressions, relative to neutral expressions. These results are discussed in terms of the cognitive model of depression proposed by Williams, Watts, MacLeod, and Mathews (1997).     

Surprise: unfolding of facial expressions

Responses to surprising events are dynamic. We argue that initial responses are primarily driven by the unexpectedness of the surprising event and reflect an interrupted and surprised state in which the outcome does not make sense yet. Later responses, after sense-making, are more likely to incorporate the valence of the outcome itself. To identify initial and later responses to surprising stimuli, we conducted two repetition-change studies and coded the general valence of facial expressions using computerised facial coding and specific facial action using the Facial Action Coding System (FACS). Results partly supported our unfolding logic. The computerised coding showed that initial expressions to positive surprises were less positive than later expressions. Moreover, expressions to positive and negative surprises were initially similar, but after some time differentiated depending on the valence of the event. Importantly, these patterns were particularly pronounced in a subset of facially expressive participants, who also showed facial action in the FACS coding. The FACS data showed that the initial phase was characterised by limited facial action, whereas the later increase in positivity seems to be explained by smiling. Conceptual as well as methodological implications are discussed.     

Recognising subtle emotional expressions: The role of facial movements

Two studies investigated the importance of dynamic temporal characteristic information in facilitating the recognition of subtle expressions of emotion. In Experiment 1 there were three conditions, dynamic moving sequences that showed the expression emerging from neutral to a subtle emotion, a dynamic presentation containing nine static stills from the dynamic moving sequences (ran together to encapsulate a moving sequence) and a First–Last condition containing only the first (neutral) and last (subtle emotion) stills. The results showed recognition was significantly better for the dynamic moving sequences than both the Dynamic-9 and First–Last conditions. Experiments 2a and 2b then changed the dynamics of the moving sequences by speeding up, slowing down or disrupting the rhythm of the motion sequences. These manipulations significantly reduced recognition, and it was concluded that in addition to the perception of change, recognition is facilitated by the characteristic muscular movements associated with the portrayal of each emotion.     

Perception of facial expressions

Three studies examined the nature of the contributions of each hemisphere to the processing of facial expressions and facial identity. A pair of faces, the members of which differed in either expression or identity, were presented to the right or left field. Subjects were required to compare the members of the pair to each other (experiments 1 and 2) or to a previously presented sample (experiment 3). The results revealed that both face and expression perception show an LVF superiority although the two tasks could be differentiated in terms of overall processing time and the interaction of laterality differences with sex. No clear-cut differences in laterality emerged for processing of positive and negative expressions.     

A smile biases the recognition of eye expressions: Configural projection from a salient mouth

A smile is visually highly salient and grabs attention automatically. We investigated how extrafoveally seen smiles influence the viewers' perception of non-happy eyes in a face. A smiling mouth appeared in composite faces with incongruent non-happy (fearful, neutral, etc.) eyes, thus producing blended expressions, or it appeared in intact faces with genuine expressions. Attention to the eye region was spatially cued while foveal vision of the mouth was blocked by gaze-contingent masking. Participants judged whether the eyes were happy or not. Results indicated that the smile biased the evaluation of the eye expression: The same non-happy eyes were more likely to be judged as happy and categorized more slowly as not happy in a face with a smiling mouth than in a face with a non-smiling mouth or with no mouth. This bias occurred when the mouth and the eyes appeared simultaneously and aligned, but also to some extent when they were misaligned and when the mouth appeared after the eyes. We conclude that the highly salient smile projects to other facial regions, thus influencing the perception of the eye expression. Projection serves spatial and temporal integration of face parts and changes.     

The power of a smile: Stronger working memory effects for happy faces in adolescents compared to adults

Theories of adolescent behaviour attribute increases in risk-taking and sensation-seeking in this age group to a heightened sensitivity to emotional stimuli on the one hand and a relatively immature cognitive control system on the other hand. However, little research has outlined to what extent relevant and irrelevant emotional stimuli bias the imbalance between affective processing and cognitive control. Thirty-three adolescents (19 females, aged 12–14) and 37 adults (18 females, aged 18–29) completed two attentional conditions of an emotional face working memory (WM) 0-back/2-back task. Participants were asked to attend to the emotional facial expression in the “relevant” emotion condition, and to the gender of the face in the “irrelevant” condition. The results revealed a WM improvement for happy faces in the relevant condition in both age groups, and an impairment for irrelevant happy faces in adolescents, but not adults. Furthermore, the difference between both attentional conditions for happy faces was larger in adolescents than adults. Results are discussed within the framework of theories of adolescent behaviour.     

Processing emotional facial expressions: The role of anxiety and awareness

In this paper, the role of self-reported anxiety and degree of conscious awareness as determinants of the selective processing of affective facial expressions is investigated. In two experiments, an attentional bias toward fearful facial expressions was observed, although this bias was apparent only for those reporting high levels of trait anxiety and only when the emotional face was presented in the left visual field. This pattern was especially strong when the participants were unaware of the presence of the facial stimuli. In Experiment 3, a patient with right-hemisphere brain damage and visual extinction was presented with photographs of faces and fruits on unilateral and bilateral trials. On bilateral trials, it was found that faces produced less extinction than did fruits. Moreover, faces portraying a fearful or a happy expression tended to produce less extinction than did neutral expressions. This suggests that emotional facial expressions may be less dependent on attention to achieve awareness. The implications of these results for understanding the relations between attention, emotion, and anxiety are discussed.     

Anger superiority effect: The importance of dynamic emotional facial expressions

A rapid response to a threatening face in a crowd is important to successfully interact in social environments. Visual search tasks have been employed to determine whether there is a processing advantage for detecting an angry face in a crowd, compared to a happy face. The empirical findings supporting the “anger superiority effect” (ASE), however, have been criticized on the basis of possible low-level visual confounds and because of the limited ecological validity of the stimuli. Moreover, a “happiness superiority effect” is usually found with more realistic stimuli. In the present study, we tested the ASE by using dynamic (and static) images of realistic human faces, with validated emotional expressions having similar intensities, after controlling the bottom-up visual saliency and the amount of image motion. In five experiments, we found strong evidence for an ASE when using dynamic displays of facial expressions, but not when the emotions were expressed by static face images.     

Repeated short presentations of morphed facial expressions change recognition and evaluation of facial expressions

This study investigated whether sensitivity to and evaluation of facial expressions varied with repeated exposure to non-prototypical facial expressions for a short presentation time. A morphed facial expression was presented for 500 ms repeatedly, and participants were required to indicate whether each facial expression was happy or angry. We manipulated the distribution of presentations of the morphed facial expressions for each facial stimulus. Some of the individuals depicted in the facial stimuli expressed anger frequently (i.e., anger-prone individuals), while the others expressed happiness frequently (i.e., happiness-prone individuals). After being exposed to the faces of anger-prone individuals, the participants became less sensitive to those individuals’ angry faces. Further, after being exposed to the faces of happiness-prone individuals, the participants became less sensitive to those individuals’ happy faces. We also found a relative increase in the social desirability of happiness-prone individuals after exposure to the facial stimuli.     

Enhancing images of facial expressions

Facial images can be enhanced by application of an algorithm--the caricature algorithm--that systematically manipulates their distinctiveness (Benson & Perrett, 1991c; Brennan, 1985). In this study, we first produced a composite facial image from natural images of the six facial expressions of fear, sadness, surprise, happiness, disgust, and anger shown on a number of different individual faces (Ekman & Friesen, 1975). We then caricatured the composite images with respect to a neutral (resting) expression. Experiment 1 showed that rated strength of the target expression was directly related to the degree of enhancement for all the expressions. Experiment 2, which used a free rating procedure, found that, although caricature enhanced the strength of the target expression (more extreme ratings), it did not necessarily enhance its purity, inasmuch as the attributes of nontarget expressions were also enhanced. Naming of prototypes, of original exemplar images, and of caricatures was explored in Experiment 3 and followed the pattern suggested by the free rating conditions of Experiment 2, with no overall naming advantage to caricatures under these conditions. Overall, the experiments suggested that computational methods of compositing and caricature can be usefully applied to facial images of expression. Their utility in enhancing the distinctiveness of the expression depends on the purity of expression in the source image.     

BRIEF REPORT The dynamic aspects of emotional facial expressions

In this study, we presented computer‐morphing animations of the facial expressions of six emotions to 43 subjects and asked them to evaluate the naturalness of the rate of change of each expression. The results showed that the naturalness of the expressions depended on the velocity of change, and the patterns for the four velocities differed with the emotions. Principal component analysis of the data extracted the structures that underlie the evaluation of dynamic facial expressions, which differed from previously reported structures for static expressions in some aspects. These results suggest that the representations of facial expressions include not only static but also dynamic properties.     

Avoidance of emotional facial expressions in social anxiety: The Approach-Avoidance Task

The Approach–Avoidance Task (AAT) was employed to indirectly investigate avoidance reactions to stimuli of potential social threat. Forty-three highly socially anxious individuals (HSAs) and 43 non-anxious controls (NACs) reacted to pictures of emotional facial expressions (angry, neutral, or smiling) or to control pictures (puzzles) by pulling a joystick towards themselves (approach) versus pushing it away from themselves (avoidance). HSAs showed stronger avoidance tendencies than NACs for smiling as well as angry faces, whereas no group differences were found for neutral faces and puzzles. In contrast, valence ratings of the emotional facial expressions did not differ between groups. A critical discrepancy between direct and indirect measures was observed for smiling faces: HSAs evaluated them positively, but reacted to them with avoidance.     

The within-subjects design in the study of facial expressions

The common within-subjects design of studies on the recognition of emotion from facial expressions allows the judgement of one face to be influenced by previous faces, thus introducing the potential for artefacts. The present study (N=344) showed that the canonical “disgust face” was judged as disgusted, provided that the preceding set of faces included “anger expressions”, but was judged as angry when the preceding set of faces excluded anger but instead included persons who looked sad or about to be sick. Chinese observers showed lower recognition of the “disgust face” than did American observers. Chinese observers also showed lower recognition of the “fear face” when responding in Chinese than in English.     

Top-down guidance in visual search for facial expressions

Using a visual search paradigm, we investigated how a top-down goal modified attentional bias for threatening facial expressions. In two experiments, participants searched for a facial expression either based on stimulus characteristics or a top-down goal. In Experiment 1, participants searched for a discrepant facial expression in a homogenous crowd of faces. Consistent with previous research, we obtained a shallower response time (RT) slope when the target face was angry than when it was happy. In Experiment 2, participants searched for a specific type of facial expression (allowing a top-down goal). When the display included a target, we found a shallower RT slope for the angry than for the happy face search. However, when an angry or happy face was present in the display in opposition to the task goal, we obtained equivalent RT slopes, suggesting that the mere presence of an angry face in opposition to the task goal did not support the well-known angry face superiority effect. Furthermore, RT distribution analyses supported the special status of an angry face only when it was combined with the top-down goal. On the basis of these results, we suggest that a threatening facial expression may guide attention as a high-priority stimulus in the absence of a specific goal; however, in the presence of a specific goal, the efficiency of facial expression search is dependent on the combined influence of a top-down goal and the stimulus characteristics.     

The categorical perception of colors and facial expressions: The effect of verbal interference

A series of five experiments examined the categorical perception previously found for color and facial expressions. Using a two-alternative forced-choice recognition memory paradigm, it was found that verbal interference selectively removed the defining feature of categorical perception. Under verbal interference, there was no longer the greater accuracy normally observed for cross-category judgments relative to within-category judgments. The advantage for cross-category comparisons in memory appeared to derive from verbal coding both at encoding and at storage. It thus appears that while both visual and verbal codes may be employed in the recognition memory for colors and facial expressions, subjects only made use of verbal coding when demonstrating categorical perception.