Lateralization for the expression and perception of facial emotion as a function of age

The effects of age and gender on the perception of lexical emotion

The primary purpose of this study was to examine the perception of lexical/verbal emotion across the adult life span. Secondary goals were to examine the contribution of gender and valence (i.e., pleasantness/unpleasantness) to the processing of lexical emotional stimuli. Participants were 28 young (ages 20-39), 28 middle-aged (ages 40-59), and 28 older (ages 60-85) right-handed adults; there were 14 men and 14 women in each age group. Age groups were comparable on demographic and cognitive variables. Participants made accuracy judgments and intensity ratings of emotional (both positive and negative) and nonemotional stimuli from lexical perception tasks from the New York Emotion Battery (Borod, Welkowitz, & Obler, 1992). Accuracy and intensity measures were not significantly correlated. When age was examined, older participants perceived emotional and nonemotional lexical stimuli with significantly less accuracy than did younger and middle-aged participants. On the other hand, older participants evaluated the nonemotional lexical stimuli as significantly more intense than younger participants. When gender was examined, lexical stimuli were processed more accurately by female than male participants. Further, emotional stimuli were rated more intense by female participants. Clinical implications of these findings are discussed.

Development of procedures for rating posed emotional expressions across facial, prosodic, and lexical channels

A number of rating systems are available to evaluate emotional communication in a single modality. The main purpose of this study was to develop procedures to train human raters to evaluate posed expressions of emotion across three different channels of communication, i.e., facial, prosodic/intonational, and lexical/verbal. These procedures were used to evaluate posed emotional expressions produced by individuals with unilateral brain lesions from stroke. Posers in this preliminary report were two right brain-damaged, two left brain-damaged, and two normal control right-handed adults who were matched on demographic and neurological factors. Eight emotional expressions, both positive and negative, were produced in three channels and rated for intensity, pleasantness, and category accuracy. 15 normal adults served as raters, five per channel. The rating procedures were comparable across channels, with analogous properties, and yielded substantial interrater agreement. In this small sample of posers, it was observed that the expressions of the right brain-damaged group were rated as the least accurate and those of the left brain-damaged group as the most intense. When patterns of individual performance across the channels were examined, performance was quiet consistent for the normal controls yet variable for the right brain-damaged persons. These observations are in keeping with the notion that patients with right hemisphere pathology have difficulty in emotional communication. In summary, these findings suggest that comparison of emotional expressions across multiple channels is feasible.

Facial asymmetry during emotional expression: gender, valence, and measurement technique

The purpose of the current study was to examine 49 extant experiments of facial asymmetry during emotional expression in normal adult males and females in regard to gender, valence, and measurement technique. When facial asymmetry was evaluated by trained judges or muscle quantification, facial expressions were left-sided, a finding implicating the right cerebral hemisphere in emotional expression. However, when self-report experiential methods were utilized, the valence hypothesis received some support. Although there was some indication in single-gender studies of greater facial lateralization for males than for females, studies involving both males and females yielded no systematic asymmetry patterns as a function of gender.

Faces and emotions: brain electric field sources during covert emotional processing

Covert brain activity related to task-free, spontaneous (i.e. unrequested), emotional evaluation of human face images was analysed in 27-channel averaged event-related potential (ERP) map series recorded from 18 healthy subjects while observing random sequences of face images without further instructions. After recording, subjects self-rated each face image on a scale from "liked" to "disliked". These ratings were used to dichotomize the face images into the affective evaluation categories of "liked" and "disliked" for each subject and the subjects into the affective attitudes of "philanthropists" and "misanthropists" (depending on their mean rating across images). Event-related map series were averaged for "liked" and "disliked" face images and for "philanthropists" and "misanthropists". The spatial configuration (landscape) of the electric field maps was assessed numerically by the electric gravity center, a conservative estimate of the mean location of all intracerebral, active, electric sources. Differences in electric gravity center location indicate activity of different neuronal populations. The electric gravity center locations of all event-related maps were averaged over the entire stimulus-on time (450 ms). The mean electric gravity center for disliked faces was located (significant across subjects) more to the right and somewhat more posterior than for liked faces. Similar differences were found between the mean electric gravity centers of misanthropists (more right and posterior) and philanthropists. Our neurophysiological findings are in line with neuropsychological findings, revealing visual emotional processing to depend on affective evaluation category and affective attitude, and extending the conclusions to a paradigm without directed task.

Hemifacial asymmetry in emotion expressions

We examined asymmetry in posed facial expression of emotions: happy and sad. Hemifacial composite photographs, left-left and right-right, were prepared, and subjects rated these for intensity of expressed emotion. Overall, left-left composites were judged to have expressed emotions relatively more intensely than the right-right composites. The significant Sex x Emotion interaction revealed that female expressors were judged as more expressive than male expressors in expressing sad facial emotion. Sex difference in expression of happy facial emotion was not significant.

Alexithymia: a right hemisphere dysfunction specific to recognition of certain facial expressions?

The most prominent features of alexithymic people are a demonstrated reduction in the ability to identify and to describe their own feelings. In recent years, these characteristics have been related to a functional disturbance of the right cerebral hemisphere. This should result in a number of other observable effects. The present study investigated whether high and low alexithymics from a nonclinical population differed in the degree of leftward perceptual bias on chimeric tasks. The chimeras consisted of pictures of faces made of up conjoined emotive and nonemotive halves as well as asymmetrically distributed stars. Differences between high and low alexithymics in the recognition of facial expressions of emotion of whole faces were also examined. High scorers on a test of alexithymia showed overall less leftward perceptual bias than low scores on the chimeric tasks and poorer recognition of facial expressions of whole faces. There was little evidence that the reduced left bias was specific to processing of emotional expressions only, or that differences in processing of facial expressions were emotion specific. These results are argued to support the right hemisphere dysfunction model of alexithymia.

Neuropsychological aspects of facial asymmetry during emotional expression: a review of the normal adult literature

This review focuses on facial asymmetries during emotional expression. Facial asymmetry is defined as the expression intensity or muscular involvement on one side of the face ("hemiface") relative to the other side and has been used as a behavioral index of hemispheric specialization for facial emotional expression. This paper presents a history of the neuropsychological study of facial asymmetry, originating with Darwin. Both quantitative and qualitative aspects of asymmetry are addressed. Next, neuroanatomical bases for facial expression are elucidated, separately for posed/voluntary and spontaneous/involuntary elicitation conditions. This is followed by a comprehensive review of 49 experiments of facial asymmetry in the adult literature, oriented around emotional valence (pleasantness/unpleasantness), elicitation condition, facial part, social display rules, and demographic factors. Results of this review indicate that the left hemiface is more involved than the right hemiface in the expression of facial emotion. From a neuropsychological perspective, these findings implicate the right cerebral hemisphere as dominant for the facial expression of emotion. In spite of the compelling evidence for right-hemispheric specialization, some data point to the possibility of differential hemispheric involvement as a function of emotional valence.

Hemispheric specialization for discourse reports of emotional experiences: relationships to demographic, neurological, and perceptual variables

This study examined hemispheric specialization for discourse reports of emotional and nonemotional experience in 16 right-brain-damaged (RBD), 16 left-brain-damaged (LBD), and 16 demographically-matched normal control (NC) right-handed adults. Patient groups did not differ on etiology, months post-CVA onset, and intrahemispheric lesion location. Subjects were requested to produce monologues about positive and negative emotional and nonemotional experiences. The lexical content of written transcriptions of these monologues was later rated for "emotionality" by naive judges. Overall, RBDs described experiences with less emotional intensity than did NCs and LBDs, providing support for right hemisphere involvement in lexical emotion. Although the RBDs in the current study demonstrated similar patterns of deficits in a prior study [9] on tasks involving lexical emotional perception, there were no significant relationships between the current measures of emotional expression and the previous measures of emotional perception. Finally, the expression and the perception data were examined with respect to intrahemispheric factors. Among the brain-damaged subjects, subcortical structures were more involved in reports of emotional experience, and cortical structures were more involved in the perception of emotion.

The neuropsychology of depression and its implications for cognitive therapy

The past few years have witnessed a growing interest in the specialty of neuropsychology as well as continued support for cognitive therapy of depression. The purpose of this paper is the examination of the neuropsychology of depression and its implications for A. T. Beck's cognitive theory and therapy of depression ([1963] "Thinking and Depression: Idiosyncratic Content and Cognitive Distortions," Archives of General Psychiatry, Vol. 9, pp. 324-333; [1964] "Thinking and Depression," Archives of General Psychiatry, Vol. 10, pp. 561-571; [1967] Depression: Clinical, Experimental, and Theoretical Aspects, New York: Harper & Row). Specifically, the neuropsychological and cognitive theory and therapy literatures related to depression are reviewed followed by an integration of these areas. Neuropsychological evidence is presented that both supports cognitive theory and therapy of depression and helps explain why such therapy may prove ineffective in treating depression. Implications for clinical practice, including neuropsychological assessment of depressives, and potential future research directions are also provided.

Laterality in facial expressions and its effect on attributions of emotion and personality: a reconsideration

Are there consistent differences between the emotions attributed to the right and left hemiface? Six studies investigated this old question, using a new technique of computerized image reconstruction that eliminates several confounding factors common in previous studies. Findings suggest that there are no consistent differences between the emotions and personality attributed to the right and the left hemiface. Nevertheless, when the two hemifaces were simultaneously compared on intensity, the left hemiface showed greater intensity in posed smiles. As a whole, the present study suggests the possibility of a slight inference of brain laterality in posed expressions, but not in resting faces.

Levels of emotional awareness and the degree of right hemispheric dominance in the perception of facial emotion

To examine correlates of individual differences in the degree of right hemispheric dominance in the perception of facial emotion, 51 medical students completed the Levy Chimeric Faces Test and an independent measure of differentiation and complexity in the processing of emotional information, the Levels of Emotional Awareness Scales. A strong positive correlation was observed between the two measures, especially when variance due to verbal ability was removed and native English speakers only were included. These results suggest that as right hemisphere dominance in the perception of facial emotion increases, the ability to perceive complexity during the processing of emotional information increases.

Is right hemisphere decline in the perception of emotion a function of aging?

The hypothesis that the right cerebral hemisphere declines more quickly than the left cerebral hemisphere in the normal aging process was tested using accuracy and intensity measures in a facial recognition test and using response time and response bias measures in a tachistoscopic paradigm. Elderly and younger men and women (N = 60) participated in both experiments. Experiment 1 required facial affect identification and intensity ratings of 50 standardized photographs of 5 affective categories: Happy, Neutral, Sad, Angry, and Fearful. The elderly were significantly less accurate in identifying facial affective valence. This effect was found using negative and neutral expressions. Results for happy expressions, however, were consistent with the younger group. In Experiment 2, age differences in hemispheric asymmetry were evaluated using presentation of affective faces in each visual field. Following prolonged experience with the affective stimuli during Experiment 1, the elderly showed heightened cerebral asymmetry for facial affect processing compared to the younger group. Both groups showed a positive affective bias to neutral stimuli presented to the left hemisphere. Elderly and younger subjects scored significantly higher on Vocabulary and Block Design subtests of the WAIS-R, respectively. Overall, the findings suggest that the elderly have more difficulty processing negative affect, while their ability to process positive affect remains intact. The results lend only partial support to the right hemi-aging hypothesis.

Patterns of perceptual asymmetry in processing facial expression

The paper reports four visual half-field experiments on the recognition of schematic faces whose emotional expression varied. Experiments I and II tested accuracy of recognition in a match-to-sample task. The results confirmed an overall left visual-field superiority in face recognition, but an analysis of a subset of the stimuli indicated that the direction and magnitude of the perceptual asymmetry depend upon the sign of the emotional expression. A replot of the results based on direct scaling of emotional expression (Experiment III) revealed an asymmetry gradient shifting from a left visual-field superiority for faces displaying hostile, aggressive emotions. When the stimuli are rotated 180 degrees the faces lose their emotional expression and no visual half-field asymmetry in recognition was observed in this condition (Experiment IV). It is concluded that emotional signals are processed independently of pattern, object and face recognition, and that the relative contribution of the left and right cerebral hemispheres to processing of emotional signals varies according to the type of emotion displayed.

Effect of unilateral contraction of hand muscles on perceiver biases in the perception of chimeric and neutral faces

Judgements of chimeric faces (half sad, half happy) showed a strong negative bias when the left face was negative. Contractions of the right hand reduced this bias but left hand contractions had no effect. The left positive faces elicited weak positive response biases that were not strongly affected by either contraction. Faces that were drawn to be neutral elicited negative or positive response biases depending on the method of presentation. When this bias was negative under control conditions left contraction had no effect, but the bias became positive following right contractions. Similarly, when the control bias was positive the right contraction had no effect, but the bias became negative following left contractions. The results are interpreted as reflecting emotional changes and shifts in lateral attention resulting from activation of the hemisphere contralateral to the contraction.

Perceiver and poser asymmetries in processing facial emotion

This study examined both perceiver and poser asymmetries in processing facial emotion. Posers were left brain-damaged (LBD), right brain-damaged (RBD), and normal control (NC) right-handed males videotaped while expressing happiness and anger. Perceivers rated the facial expressions for asymmetry in original and reversed orientations. Overall, expressions viewed in the reversed orientation were rated as more left-sided than in the original orientation. In the reversed orientation, the more extensive left hemiface of the NCs and LBDs fell in the perceiver's left hemispace. This finding is consistent with previous research demonstrating a left hemispace bias for free-field viewing of emotional faces. Expressions were produced significantly more intensely on the left than the right hemiface by NCs and LBDs; expressions of RBDs were not significantly lateralized.