Right hemisphere language: Remaining problems.

Responds to J. J. Myers's (1984) critique of the present author's (see record 1984-07149-001) assertion that the incidence of right-hemisphere language (RHL) capacity is relatively infrequent in human split-brain cases (SBCs). The following areas of Myers's concerns are addressed: (1) the demographics of RHL, (2) neurologic criteria for considering a commissurotomy patient worthy of study, and (3) the suitability of considering patients with explicit sparing of the anterior commissure as SBCs. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Right hemisphere language: Science or fiction?

Reviews inconsistencies and misrepresentations in M. S. Gazzaniga's (see record 1984-07149-001) analysis of 3 series of patients who underwent brain bisection. The inaccuracies led to the conclusion that right-hemisphere (RH) language and cognition are a rarity attributable to left-hemisphere brain damage. Gazzaniga's data fail to make a substantive contribution to the understanding of RH language or cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Right hemisphere superiority in visual orientation matching.

"Same" or "different" judgments were made by 22 right-handed college students in 2 orientation matching tasks. In 1 task pairs of lines were presented 4. left or right of fixation. Reaction times for both "same" and "different" judgments were faster if stimulus pairs were presented to the left visual field, indicating superiority of the right hemisphere for handling spatial information. In the other task the orientation of a standard line, held in memory, was compared with the orientation of a single test line projected to the left or right of fixation. Results were in the same direction as before, although the right hemisphere superiority was significant only for the "different" responses. Data do not support the idea that "same" and "different" judgments need be differentially lateralized. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Right hemisphere language following brain bisection: A 20-year perspective.

Reviews studies on 3 series of patients who underwent brain bisection. A review of right-hemisphere language in split-brain patients suggests that it occurs infrequently. When present in these patients, right-hemisphere linguistic competence ranges from simple comprehensive skills to a system that can both recognize written and spoke language and produce speech. In almost all cases, the existence of right-hemisphere language is attributable to early left-hemisphere brain damage. Such patients prove valuable for the study of global mechanisms of mind, such as those underlying the sense of conscious unity. These studies indicate that subjective awareness arises out of the dominant left hemisphere's unrelenting need to explain actions from a multitude of mental systems. Second, a half-brain system does not seem to be cognitively sophisticated without language despite certain visual-spatial skills. Third, the awareness that the 2 cognitive systems interact at important levels in attentional process and semantics suggests that a variety of subcallosal brain mechanisms may be involved. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Left hemisphere specialization for response to positive emotional expressions: A divided output methodology.

An extensive literature credits the right hemisphere with dominance for processing emotion. Conflicting literature finds left hemisphere dominance for positive emotions. This conflict may be resolved by attending to processing stage. A divided output (bimanual) reaction time paradigm in which response hand was varied for emotion (angry; happy) in Experiments 1 and 2 and for gender (male; female) in Experiment 3 focused on response to emotion rather than perception. In Experiments 1 and 2, reaction time was shorter when right-hand responses indicated a happy face and left-hand responses an angry face, as compared to reversed assignment. This dissociation did not obtain with incidental emotion (Experiment 3). Results support the view that response preparation to positive emotional stimuli is left lateralized. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How emotional auditory stimuli modulate time perception.

Emotional and neutral sounds rated for valence and arousal were used to investigate the influence of emotions on timing in reproduction and verbal estimation tasks with durations from 2 s to 6 s. Results revealed an effect of emotion on temporal judgment, with emotional stimuli judged to be longer than neutral ones for a similar arousal level. Within scalar expectancy theory (J. Gibbon, R. Church, & W. Meck, 1984), this suggests that emotion-induced activation generates an increase in pacemaker rate, leading to a longer perceived duration. A further exploration of self-assessed emotional dimensions showed an effect of valence and arousal. Negative sounds were judged to be longer than positive ones, indicating that negative stimuli generate a greater increase of activation. High-arousing stimuli were perceived to be shorter than low-arousing ones. Consistent with attentional models of timing, this seems to reflect a decrease of attention devoted to time, leading to a shorter perceived duration. These effects, robust across the 2 tasks, are limited to short intervals and overall suggest that both activation and attentional processes modulate the timing of emotional events. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hemispheric perception of emotional valence from facial expressions.

The authors previously reported that normal subjects are better at discriminating happy from neutral faces when the happy face is located to the viewer's right of the neutral face; conversely, discrimination of sad from neutral faces is better when the sad face is shown to the left, supporting a role for the left hemisphere in processing positive valence and for the right hemisphere in processing negative valence. Here, the authors extend this same task to subjects with unilateral cerebral damage (31 right, 28 left). Subjects with right damage performed worse when discriminating sad faces shown on the left, consistent with the prior findings. However, subjects with either left or right damage actually performed superior to normal controls when discriminating happy faces shown on the left. The authors suggest that perception of negative valence relies preferentially on the right hemisphere, whereas perception of positive valence relies on both left and right hemispheres. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neurocognitive underpinnings of face perception: Further evidence of distinct person and group perception processes.

A model of social perception is presented and tested. The model is based on cognitive neuroscience models and proposes that the right cerebral hemisphere is more efficient at processing combinations of features whereas the left hemisphere is superior at identifying single features. These processes are hypothesized to produce person and group-based representations, respectively. Individuating or personalizing experience with an outgroup member was expected to facilitate the perception of the individuating features and inhibit the perception of the group features. In the presented study, participants were asked to learn about various ingroup and outgroup targets. Later, participants demonstrated that categorization response speeds to old targets were slower in the left hemisphere than in the right, particularly for outgroup members, as predicted. These findings are discussed for their relevance to models of social perception and stereotyping. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hemispheric aymmetries in adults' perception of infant emotional expressions.

Accounts of emotion lateralization propose either overall right hemisphere (RH) advantage or differential RH vs left hemisphere (LH) involvement depending on the negative–positive valence of emotions. Perceptual studies generally show RH specialization. Yet viewer emotional responses may enhance valence effects. Because infant faces elicit heightened emotion in viewers, perceptual asymmetries with chimeric infant faces were assessed. First, it was determined that chimeras must be paired with their counterparts, not their mirror images, to tap viewers' sensitivity to adult facial asymmetries. Results showed an RH perceptual bias for infant cries but bihemispheric sensitivity to asymmetries in infant smiles. This effect was not due to LH featural vs RH holistic processing and held for additional, intensity-matched, spontaneous expressions. Specialized RH sensitivity to infant cries may reflect an evolutionary advantage for rapid response to infant distress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parental perception of emotional expressiveness in children with autism.

Parents' perceptions of their children's emotional expressiveness, and possible bases for these perceptions, were investigated in a study comparing older, nonretarded autistic and normal children and in another study comparing young autistic, mentally retarded, and normal children. Both groups of autistic children were perceived as showing more negative emotion and less positive emotion than comparison children. In the younger sample, parental perceptions correlated with the children's attention and responsiveness to others' displays of emotion in 2 laboratory situations. Findings contradict the view that autism involves the "absence of emotional reaction." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Strength and vulnerability integration: A model of emotional well-being across adulthood.

The following article presents the theoretical model of strength and vulnerability integration (SAVI) to explain factors that influence emotion regulation and emotional well-being across adulthood. The model posits that trajectories of adult development are marked by age-related enhancement in the use of strategies that serve to avoid or limit exposure to negative stimuli but by age-related vulnerabilities in situations that elicit high levels of sustained emotional arousal. When older adults avoid or reduce exposure to emotional distress, they often respond better than younger adults; when they experience high levels of sustained emotional arousal, however, age-related advantages in emotional well-being are attenuated, and older adults are hypothesized to have greater difficulties returning to homeostasis. SAVI provides a testable model to understand the literature on emotion and aging and to predict trajectories of emotional experience across the adult life span. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Embodied auditory perception: The emotional impact of approaching and receding sound sources.

Research has shown the existence of perceptual and neural bias toward sounds perceived as sources approaching versus receding a listener. It has been suggested that a greater biological salience of approaching auditory sources may account for these effects. In addition, these effects may hold only for those sources critical for our survival. In the present study, we bring support to these hypotheses by quantifying the emotional responses to different sounds with changing intensity patterns. In 2 experiments, participants were exposed to artificial and natural sounds simulating approaching or receding sources. The auditory-induced emotional effect was reflected in the performance of participants in an emotion-related behavioral task, their self-reported emotional experience, and their physiology (electrodermal activity and facial electromyography). The results of this study suggest that approaching unpleasant sound sources evoke more intense emotional responses in listeners than receding ones, whereas such an effect of perceived sound motion does not exist for pleasant or neutral sound sources. The emotional significance attributed to the sound source itself, the loudness of the sound, and loudness change duration seem to be relevant factors in this disparity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Variability across sources of performance ratings: Further evidence.

33 1st-yr graduate students (aged 21–55 yrs) completed a simulated counseling interview. Self-, peer, and supervisor ratings were obtained for the simulated interviews using 7 measures of counseling performance. A multiple analysis of variance (MANOVA) indicated statistically significant differences among self-, peer, and supervisor ratings. Analyses also showed significant differences on 4 of the 7 dependent measures. Implications for training are discussed. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The golf-ball illusion: evidence for top-down processing in weight perception

After partial denervation, the remaining motor units (MUs) of adult fast extensor digitorum longus muscle (EDL) expand their peripheral field. The time course of this event was studied using tension measurement and recordings of electromyographic (EMG) activity. The results show that after section of the L4 spinal nerve, when only 5.3 +/- 0.63 of the 40 MUs normally supplying EDL muscle remain, the force of individual motor units starts to increase between the 1st and 2nd week after the operation and continues to do so for a further week. The drastic reduction of the number of motoneurones supplying the fast EDL leads to an increase in activity of the remaining MUs. In the 1st week after partial denervation, there was a sharp increase in the EMG activity of remaining motor units. During the next 12 days, this increase became less marked, but EMG activity remained nevertheless significantly higher than that of the unoperated EDL muscle. Many MUs became tonically active during posture. The EMG activity pattern during locomotion was also altered, so that the burst duration was positively correlated with the step cycle duration. Moreover, shortly after partial denervation, the interlimb coordination was disturbed but returned to its original symmetrical use 1-2 weeks later.     

Differential accuracy in person perception across traits: Examination of a functional hypothesis.

Although strangers can assess certain traits of unacquainted others with moderate validity, overall validity is low. Differential validity across traits may be due to (1) the extent to which targets display valid cues or (2) the extent to which perceivers validly use cues. A functionalist perspective suggests that valid cue utilization should vary with how important the consequences of accurate trait assessment are. It was predicted from this perspective that perceivers would judge strangers' sociosexuality more accurately than 3 other traits (social potency, social closeness, and stress reaction). Perceivers viewed 1-min videotaped segments of targets being interviewed and rated them on the 4 traits. Ratings were correlated with target-reported trait measures. As predicted, perceivers' ratings of male sociosexuality agreed relatively well with self-reports. This effect was moderated by sex of target and sex of perceiver. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Baby, it's in your smile: Right hemiface bias in infant emotional expressions.

Adult facial expressions are more intense on the left hemiface, suggesting right hemisphere emotional specialization. In this research, adult judgments of mirror-image chimeras indicated that infant expressions are more intense on the right hemiface, which is not predicted by current models of adult cerebral asymmetries. The rightward bias was stronger when judgments were restricted to the central facial features in computer-digitized images of the chimeric faces. Because the mouth and eye regions receive contralateral versus bilateral cortical input, respectively, separate judgments of the mouth and eyes/brows were obtained. Only the mouths showed a significant rightward bias, implicating cortical rather than lower-level mechanisms. The results were replicated with a second set of infants. The findings are interpreted as support for a right-to-left gradient in development of cortical inhibition over subcortical influences on facial expressions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Decomposing visual search: evidence of multiple item-specific skills

Four experiments demonstrated that visual search can be decomposed into two components: one consisting of skills shared with memory search and the other consisting of skills not shared with memory search. A training-transfer paradigm was used to test for transfer from memory search to visual search and vice versa. When the same targets and distractors were used in training and transfer, visual search practice completely trained memory search, but memory search practice only partially trained visual search. Learning on both the shared and the private components of visual search benefited more from item-specific training than from nonspecific training. The relationship between the components and some theorized models of visual search are discussed, particularly in terms of prioritization learning.     

A dual mechanism for sound pitch perception: new evidence from brain electrophysiology

The N1 component of the auditory brain evoked potential was used as a direct electrophysiological index, to study how the perception of pitch for complex periodic tones can be influenced by the phase of the harmonics that make up a sound, according to their ranks. Results showed that in the low pitch and/or high spectra region, N1 latency was modified by phase, whereas it was not in the high pitch and low spectra region. These data help bring evidence towards a dual mechanism for pitch perception, and demonstrate that these processes take place within 110 ms following stimulus onset. Results are compatible with a model based on the resolvability of components and on the bandwidth of auditory filters.