Hemispheric differences in recognizing upper and lower facial displays of emotion.

OBJECTIVE: To determine if there are hemispheric differences in processing upper versus lower facial displays of emotion. BACKGROUND: Recent evidence suggests that there are two broad classes of emotions with differential hemispheric lateralization. Primary emotions (e.g. anger, fear) and associated displays are innate, are recognized across all cultures, and are thought to be modulated by the right hemisphere. Social emotions (e.g., guilt, jealousy) and associated "display rules" are learned during early child development, vary across cultures, and are thought to be modulated by the left hemisphere. Display rules are used by persons to alter, suppress or enhance primary emotional displays for social purposes. During deceitful behaviors, a subject's true emotional state is often leaked through upper rather than lower facial displays, giving rise to facial blends of emotion. We hypothesized that upper facial displays are processed preferentially by the right hemisphere, as part of the primary emotional system, while lower facial displays are processed preferentially by the left hemisphere, as part of the social emotional system. METHOD: 30 strongly right-handed adult volunteers were tested tachistoscopically by randomly flashing facial displays of emotion to the right and left visual fields. The stimuli were line drawings of facial blends with different emotions displayed on the upper versus lower face. The subjects were tested under two conditions: 1) without instructions and 2) with instructions to attend to the upper face. RESULTS: Without instructions, the subjects robustly identified the emotion displayed on the lower face, regardless of visual field presentation. With instructions to attend to the upper face, for the left visual field they robustly identified the emotion displayed on the upper face. For the right visual field, they continued to identify the emotion displayed on the lower face, but to a lesser degree. CONCLUSIONS: Our results support the hypothesis that hemispheric differences exist in the ability to process upper versus lower facial displays of emotion. Attention appears to enhance the ability to explore these hemispheric differences under experimental conditions. Our data also support the recent observation that the right hemisphere has a greater ability to recognize deceitful behaviors compared with the left hemisphere. This may be attributable to the different roles the hemispheres play in modulating social versus primary emotions and related behaviors.

Impaired affective prosody in AD: relationship to aphasic deficits and emotional behaviors.

OBJECTIVE: To assess the ability of patients with AD to produce, repeat, and comprehend affective prosody in relationship to severity of dementia, aphasic deficits, and changes in emotional behaviors. METHODS: An Aprosodia Battery was used to assess affective-prosodic performance and to identify patterns of deficits in affective communication. In addition, the presence and severity of aberrant behaviors, depression, and aphasia were assessed using standardized assessment tools. RESULTS: Patients with AD had significant impairments in their ability to repeat, comprehend, and discriminate affective aspects of speech, but maintained normal spontaneous affective-prosodic performances. As dementia severity increased, performance on the comprehension tasks and, to a lesser degree, on the repetition tasks became more impaired; spontaneous affective prosody remained normal. In the current study, affective-prosodic comprehension impairments were present in patients with all stages of AD; comparable aphasic deficits were not observed until patients were severely demented. The majority of aphasic deficits involved anomia without loss of comprehension. Patients with AD with sensory aprosodia had increased frequency and severity of behavioral changes whereas patients with AD with normal affective-prosodic performance were significantly less demented, had normal linguistic ability, and displayed fewer aberrant psychiatric behaviors. CONCLUSION: Patients with mild AD are at considerable risk for affective-prosodic comprehension deficits. As patients become more demented and develop sensory aprosodia, they are at greater risk for disturbances in behavior and mood.

Affective-prosodic deficits in schizophrenia: comparison to patients with brain damage and relation to schizophrenic symptoms [corrected].

OBJECTIVE: Although affective prosody seems to be a dominant and lateralised communication function of the right hemisphere, focal lesions of either hemisphere may cause problems with its modulation. When impairment occurs after brain damage, the profiles of affective-prosodic disturbances differ depending on the hemisphere injured. Patients with left brain damage (LBD) improve their performance whereas patients with right brain damage (RBD) do not when the verbal-articulatory demands of the test stimuli are reduced systematically. One of the major arguments for a right hemispheric contribution to schizophrenia has been the documentation of affective prosodic deficits under the assumption that these abnormalities reflect right hemispheric dysfunction. Thus, an essential question to resolve is whether the profile of affective prosodic disturbances in schizophrenia is similar to LBD or RBD, or represents a unique variation. METHODS: Data were collected from four subject groups: 45 chronic, medication-stabilised, schizophrenic patients, 10 patients with focal LBD, nine patients with focal RBD, and 19 controls. All groups were tested on the aprosodia battery, which uses stimuli having incrementally reduced verbal-articulatory demands. Schizophrenic and aphasic symptoms were evaluated using standard assessment tools. RESULTS: For patients with impaired performance on the aprosodia battery, schizophrenic patients were statistically identical to patients with RBD and robustly different from those with LBD. Thirty eight schizophrenic patients (84.4%) were found to have some type of affective prosodic deficit with the predominant pattern indicating, at minimum, right posterior sylvian dysfunction (57.8%). When schizophrenic symptoms and aprosodic deficits were examined using a principal component analysis, affective comprehension and repetition loaded uniquely as separate factors. CONCLUSIONS: The profile of affective-prosodic deficits found in impaired schizophrenic patients is characteristic of RBD, supporting the concept that schizophrenia is a bihemispheric disease process. These deficits may also represent cardinal symptoms of schizophrenia as they are highly prevalent and, except for spontaneous affective prosody, are not associated statistically with traditional clusters of schizophrenic symptoms.