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.     

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.     

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.     

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.     

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.     

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.     

Representation of facial expressions of emotion

Inversion interferes with the encoding of configural and holistic information more than it does with the encoding of explicitly represented and isolated parts. Accordingly, if facial expressions are explicitly represented in the face representation, their recognition should not be greatly affected by face orientation. In the present experiment, response times to detect a difference in hair color in line-drawn faces were unaffected by face orientation, but response times to detect the presence of brows and mouth were longer with inverted than with upright faces, independent of the emergent expression (neutral, happy, sad, and angry). Expressions are not explicitly represented; rather, they and the face configuration are represented as undecomposed wholes.     

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.     

Categorical perception of facial expressions.

People universally recognize facial expressions of happiness, sadness, fear, anger, disgust, and perhaps, surprise, suggesting a perceptual mechanism tuned to the facial configuration displaying each emotion. Sets of drawings were generated by computer, each consisting of a series of faces differing by constant physical amounts, running from one emotional expression to another (or from one emotional expression to a neutral face). Subjects discriminated pairs of faces, then, in a separate task, categorized the emotion displayed by each. Faces within a category were discriminated more poorly than faces in different categories that differed by an equal physical amount. Thus emotional expressions, like colors and speech sounds, are perceived categorically, not as a direct reflection of their continuous physical properties.     

Configural coding of facial expressions: The impact of inversion and photographic negative

In previous research we used the composite paradigm (Young, Hellawell, & Hay, ) to demonstrate that configural cues are important for interpreting facial expressions. However, different configural cues in face perception have been identified, including holistic processing (i.e., perception of facial features as a single gestalt) and second‐order spatial relations (i.e., the spatial relationship between individual features). Previous research has suggested that the composite effect for facial identity operates at the level of holistic encoding. Here we show that the composite effect for facial expression has a similar perceptual basis by using different graphic manipulations (stimulus inversion and photographic negative) in conjunction with the composite paradigm. In relation to Bruce and Young's () functional model of face recognition, a suitable level for the composite effect is a stage of front‐end processing referred to as structural encoding, that is common to both facial identity and facial expression perception.     

Inhibiting and facilitating conditions of the human smile: a nonobtrusive test of the facial feedback hypothesis

We investigated the hypothesis that people's facial activity influences their affective responses. Two studies were designed to both eliminate methodological problems of earlier experiments and clarify theoretical ambiguities. This was achieved by having subjects hold a pen in their mouth in ways that either inhibited or facilitated the muscles typically associated with smiling without requiring subjects to pose in a smiling face. Study 1's results demonstrated the effectiveness of the procedure. Subjects reported more intense humor responses when cartoons were presented under facilitating conditions than under inhibiting conditions that precluded labeling of the facial expression in emotion categories. Study 2 served to further validate the methodology and to answer additional theoretical questions. The results replicated Study 1's findings and also showed that facial feedback operates on the affective but not on the cognitive component of the humor response. Finally, the results suggested that both inhibitory and facilitatory mechanisms may have contributed to the observed affective responses.     

Duchenne smile,emotional experience,and autonomic reactivity: a test of the facial feedback hypothesis

This study examined the modulatory function of Duchenne and non-Duchenne smiles on subjective and autonomic components of emotion. Participants were asked to hold a pencil in their mouth to either facilitate or inhibit smiles and were not instructed to contract specific muscles. Five conditions--namely lips pressing, low-level non-Duchenne smiling, high-level non-Duchenne smiling, Duchenne smiling, and control--were produced while participants watched videoclips that were evocative of positive or negative affect. Participants who displayed Duchenne smiles reported more positive experience when pleasant scenes and humorous cartoons were presented. Furthermore, they tended to exhibit different patterns of autonomic arousal when viewing positive scenes. These results support thefacial feedback hypothesis and suggest that facial feedback has more powerful effects when facial configurations represent valid analogs of basic emotional expressions.     

The City Infant Faces Database: A validated set of infant facial expressions

Adults need to be able to process infants’ emotional expressions accurately to respond appropriately and care for infants. However, research on processing of the emotional expressions of infant faces is hampered by the lack of validated stimuli. Although many sets of photographs of adult faces are available to researchers, there are no corresponding sets of photographs of infant faces. We therefore developed and validated a database of infant faces, which is available via e-mail request. Parents were recruited via social media and asked to send photographs of their infant (0–12 months of age) showing positive, negative, and neutral facial expressions. A total of 195 infant faces were obtained and validated. To validate the images, student midwives and nurses (n = 53) and members of the general public (n = 18) rated each image with respect to its facial expression, intensity of expression, clarity of expression, genuineness of expression, and valence. On the basis of these ratings, a total of 154 images with rating agreements of at least 75% were included in the final database. These comprise 60 photographs of positive infant faces, 54 photographs of negative infant faces, and 40 photographs of neutral infant faces. The images have high criterion validity and good test–retest reliability. This database is therefore a useful and valid tool for researchers.     

The influence of indirect and direct emotional processing on memory for facial expressions

We used the remember-know procedure (Tulving, 1985 ) to test the behavioural expression of memory following indirect and direct forms of emotional processing at encoding. Participants (N=32) viewed a series of facial expressions (happy, fearful, angry, and neutral) while performing tasks involving either indirect (gender discrimination) or direct (emotion discrimination) emotion processing. After a delay, participants completed a surprise recognition memory test. Our results revealed that indirect encoding of emotion produced enhanced memory for fearful faces whereas direct encoding of emotion produced enhanced memory for angry faces. In contrast, happy faces were better remembered than neutral faces after both indirect and direct encoding tasks. These findings suggest that fearful and angry faces benefit from a recollective advantage when they are encoded in a way that is consistent with the predictive nature of their threat. We propose that the broad memory advantage for happy faces may reflect a form of cognitive flexibility that is specific to positive emotions.