Right hemisphere dominance for emotion processing in baboons

Asymmetries of emotional facial expressions in humans offer reliable indexes to infer brain lateralization and mostly revealed right hemisphere dominance. Studies concerned with oro-facial asymmetries in nonhuman primates largely showed a left-sided asymmetry in chimpanzees, marmosets and macaques. The presence of asymmetrical oro-facial productions was assessed in Olive baboons in order to determine the functional cerebral asymmetries. Two affiliative behaviors (lipsmack, copulation call) and two agonistic ones (screeching, eyebrow-raising) were recorded. For screeching, a strong and significant left hemimouth bias was found, but no significant bias was observed for the other behaviors. These results are discussed in the light of the available literature concerning asymmetrical oro-facial productions in nonhuman primates. In addition, these findings suggest that human hemispheric specialization for emotions has precursors in primate evolution.     

Dissociating linguistic and non-linguistic gesture processing: electrophysiological evidence from American Sign Language

A fundamental advance in our understanding of human language would come from a detailed account of how non-linguistic and linguistic manual actions are differentiated in real time by language users. To explore this issue, we targeted the N400, an ERP component known to be sensitive to semantic context. Deaf signers saw 120 American Sign Language sentences, each consisting of a “frame” (a sentence without the last word; e.g. BOY SLEEP IN HIS) followed by a “last item” belonging to one of four categories: a high-close-probability sign (a “semantically reasonable” completion to the sentence; e.g. BED), a low-close-probability sign (a real sign that is nonetheless a “semantically odd” completion to the sentence; e.g. LEMON), a pseudo-sign (phonologically legal but non-lexical form), or a non-linguistic grooming gesture (e.g. the performer scratching her face). We found significant N400-like responses in the incongruent and pseudo-sign contexts, while the gestures elicited a large positivity.     

Automatic processing of dominance and submissiveness

We investigated whether people are able to detect in a relatively automatic manner the dominant or submissive status of persons engaged in social interactions. We used a nonaffective variant of the affective Simon paradigm of De Houwer and Eelen (1998) in which participants responded by saying either "dominant" or "submissive" depending on the right or left spatial position of a target person who was engaged as either the dominant or the submissive agent in a social interaction. We observed that responses were facilitated when the status connotation of the target person and the correct response corresponded. These results provide new information about the automatic nature of information related to emotion-antecedent appraisals.     

Discrimination of second-formant-like frequency transitions

Discrimination of two types of simulated single-second-formant: frequency transitions was studied, transitions where members of a stimulus set shared the same onset frequency and transitions where stimuli of a set shared the same offset frequency. Experiment 1 employed an adaptive procedure to measure just-noticeable differences for transitions that increased in frequency. Experiment 2 obtained complete psychometric functions, based on a three-interval,forced choice procedure,for transitions that either increased or decreased in frequency. In both experiments, better discrimination occurred for longer stimuli, measured in hertz/millisecond, and for transitions that shared the same onset frequency. There were no differences, in Experiment 2, between discrimination of rising and falling transitions. Results are considered from several theoretical perspectives.     

Discrimination of second-format-like frequency transitions

Discrimination of two types of simulated single-second-format frequency transitions was studied, transitions where members of a stimulus set shared the same onset frequency and transitions where stimuli of a set shared the same offset frequency. Experiment 1 employed an adaptive procedure to measure just-noticeable differences for transitions that increased in frequency. Experiment 2 obtained complete psychometric functions, based on a three-interval, forced-choice procedure, for transitions that either increased or decreased in frequency. In both experiments, better discrimination occurred for longer stimuli, measured in hertz/millisecond, and for transitions that shared the same onset frequency. There were no differences, in Experiment 2, between discrimination of rising and falling transitions. Results are considered from several theoretical perspectives.     

Hand dominance influences the processing of observed bodies

In motor tasks, subgroups of lefthanders have been shown to differ in the distribution of attention about their own bodies. The present experiment examined whether similar attentional biases also apply when processing observed bodies. Sixteen right handers (RHs), 22 consistent left handers (CLHs) and 11 relatively ambidextrous inconsistent left handers (ILHs) performed an own body transformation task in which they were instructed to make speeded left–right judgements about a schematic human figure. Attentional biases associated with handedness were found to extend to observed bodies: CLHs’ judgements were faster to the figure’s left side, while ILHs, like RHs, showed facilitated performance to the figure’s right side. These results demonstrate a novel embodiment effect whereby the processing of a static schematic human figure is modulated by an individual’s personal motor capabilities. This finding suggests that motor simulation may contribute to whole body perception in the absence of actual or implied actions.     

Right hemispheric dominance in processing of unconscious negative emotion

Right hemispheric dominance in unconscious emotional processing has been suggested, but remains controversial. This issue was investigated using the subliminal affective priming paradigm combined with unilateral visual presentation in 40 normal subjects. In either left or right visual fields, angry facial expressions, happy facial expressions, or plain gray images were briefly presented as negative, positive, and control primes, followed by a mosaic mask. Then nonsense target ideographs were presented, and the subjects evaluated their partiality toward the targets. When the stimuli were presented in the left, but not the right, visual fields, the negative primes reduced the subjects' liking for the targets, relative to the case of the positive or control primes. These results provided behavioral evidence supporting the hypothesis that the right hemisphere is dominant for unconscious negative emotional processing.     

Right hemispheric dominance in processing of unconscious negative emotion

Right hemispheric dominance in unconscious emotional processing has been suggested, but remains controversial. This issue was investigated using the subliminal affective priming paradigm combined with unilateral visual presentation in 40 normal subjects. In either left or right visual fields, angry facial expressions, happy facial expressions, or plain gray images were briefly presented as negative, positive, and control primes, followed by a mosaic mask. Then nonsense target ideographs were presented, and the subjects evaluated their partiality toward the targets. When the stimuli were presented in the left, but not the right, visual fields, the negative primes reduced the subjects’ liking for the targets, relative to the case of the positive or control primes. These results provided behavioral evidence supporting the hypothesis that the right hemisphere is dominant for unconscious negative emotional processing.     

Involuntary processing of social dominance cues from bimodal face-voice displays

Social-rank cues communicate social status or social power within and between groups. Information about social-rank is fluently processed in both visual and auditory modalities. So far, the investigation on the processing of social-rank cues has been limited to studies in which information from a single modality was assessed or manipulated. Yet, in everyday communication, multiple information channels are used to express and understand social-rank. We sought to examine the (in)voluntary nature of processing of facial and vocal signals of social-rank using a cross-modal Stroop task. In two experiments, participants were presented with face-voice pairs that were either congruent or incongruent in social-rank (i.e. social dominance). Participants’ task was to label face social dominance while ignoring the voice, or label voice social dominance while ignoring the face. In both experiments, we found that face-voice incongruent stimuli were processed more slowly and less accurately than were the congruent stimuli in the face-attend and the voice-attend tasks, exhibiting classical Stroop-like effects. These findings are consistent with the functioning of a social-rank bio-behavioural system which consistently and automatically monitors one’s social standing in relation to others and uses that information to guide behaviour.     

Methamphetamine effects on cognitive processing during extended wakefulness

We examined the effects of both 5- and 10-mg/7O kg body weight of d-methamphetamine HCl on high event rate vigilance and tracking performance in a 13.5-hr sustained-performance session during one night of sleep loss. At 0116 hours participants were administered either a 5 mg/70 kg oral dose of d-methamphetamine (n=10), 10 mg/70 kg d-methamphetamine (n=10), or a placebo (n=10) using standard double-blind procedures. Performance on all measures degraded markedly during the night in the placebo group. Both the 5- and 10-mg methamphetamines treatment reversed an initial decline in d', and reversed increases in nonresponses (lapses) and tracking error within approximately 3 hr of administration. No evidence that amphetamine treatment increased impulsive responding (fast guesses) was observed. The magnitude of the performance effects of the methamphetamine treatments was similar at 3 hr postadministration. However, the effects of the 5-mg dose were shorter-lived, disappearing by the last testing session (6.5 hr postadministration), whereas effects of the 10-mg dose tended to remain throughout testing. Both amphetamine treatments decreased subjective sleepiness during the night and tended to increase subjective sleep latencies during a post-testing sleep period.     

Age differences in discrimination of simulated single-formant frequency transitions

We studied auditory discrimination of simulated single-formant frequency transitions that resembled portions of certain speech consonants. Significant age differences in transition discrimination occurred; both children and older adults required larger acoustic differences between transitions for discrimination than did teenagers/young adults. Longer transitions were more easily discriminated than shorter transitions by all listeners, and there were no differences between discriminations of rising and falling transitions. Teens/young adults and older adults, but not children, required larger frequency differences to discriminate frequency transitions followed by a steady-state sound than for transitions alone. There were also age differences in discrimination of steady-state sounds. These developmental-perceptual differences may help explain why children and older adults who have good pure-tone sensitivity may experience difficulty in understanding speech.     

Global and local processing in nonattended objects: a failure to induce local processing dominance.

Paquet and Merikle (1988) found that subjects can ignore the category of unattended local forms but not that of global forms. Does this finding reflect a priority for global information during perception? In 5 studies, 2 compound stimuli, each surrounded by a frame, were presented side by side, and attention was directed to 1 of the stimuli. The first 2 studies examined whether local dominance would emerge if a small gap (Experiment 1) or the presence of small white lines (Experiment 2) on the surrounding frame specified the target object. No evidence for local dominance was found. Three additional studies examined whether local dominance would be obtained if subjects had extensive practice identifying the local aspect of stimulus displays. Although local practice led to automatic detection of unattended local targets, it did not affect the processing of the global aspect. These results are proposed to exemplify the priority of global information during perception.     

The frequency concept of disposition: dominance and prototypically dominant acts1

Three studies of dominance explore the frequency concept of disposition, which entails categories of acts that are topographically dissimilar but nonetheless considered to be manifestations of a common disposition. In the first study, 100 different acts presumably belonging to the category of dominance were generated through a nomination procedure. In the second study, expert and student panels rated how prototypically dominant each act is, defined in terms of centrality of membership in the category of dominant acts. In this manner, an internal structure of the act category was specified such that some acts are more prototypically dominant while others are more peripheral members. Substantial agreement in these ratings exists within and between panels. The third study found that a multiple-act criterion based on prototypically dominant acts is predicted by personality scales with significantly greater success than are multiple-act criteria based on more peripheral acts within the dominance domain. Discussion focuses on specifying the appropriate act category for other frequency dispositions and follow-up field studies of them. Implications for alternative notions of disposition (e.g., purposive-cognitive concepts) are considered.     

Central auditory processing. VI. Detecting ear dominance by evoked potentials

An electrophysiological method is described for measuring the direction and strength of a subject's ear dominance for pitch using the P3 component of event-related potentials. Results of these experiments reveal that the P3 can be used effectively for these measures in man.     

Neural network processing of natural language: II. Towards a unified model of corticostriatal function in learning sentence comprehension and non-linguistic sequencing

A central issue in cognitive neuroscience today concerns how distributed neural networks in the brain that are used in language learning and processing can be involved in non-linguistic cognitive sequence learning. This issue is informed by a wealth of functional neurophysiology studies of sentence comprehension, along with a number of recent studies that examined the brain processes involved in learning non-linguistic sequences, or artificial grammar learning (AGL). The current research attempts to reconcile these data with several current neurophysiologically based models of sentence processing, through the specification of a neural network model whose architecture is constrained by the known cortico-striato-thalamo-cortical (CSTC) neuroanatomy of the human language system. The challenge is to develop simulation models that take into account constraints both from neuranatomical connectivity, and from functional imaging data, and that can actually learn and perform the same kind of language and artificial syntax tasks. In our proposed model, structural cues encoded in a recurrent cortical network in BA47 activate a CSTC circuit to modulate the flow of lexical semantic information from BA45 to an integrated representation of meaning at the sentence level in BA44/6. During language acquisition, corticostriatal plasticity is employed to allow closed class structure to drive thematic role assignment. From the AGL perspective, repetitive internal structure in the AGL strings is encoded in BA47, and activates the CSTC circuit to predict the next element in the sequence. Simulation results from Caplan's [Caplan, D., Baker, C., & Dehaut, F. (1985). Syntactic determinants of sentence comprehension in aphasia. Cognition, 21, 117-175] test of syntactic comprehension, and from Gomez and Schvaneveldts' [Gomez, R. L., & Schvaneveldt, R. W. (1994). What is learned from artificial grammars?. Transfer tests of simple association. Journal of Experimental Psychology: Learning, Memory and Cognition, 20, 396-410] artificial grammar learning experiments are presented. These results are discussed in the context of a brain architecture for learning grammatical structure for multiple natural languages, and non-linguistic sequences.     

Word frequency and root-morpheme frequency effects on processing of Korean particle-suffixed words

Two experiments investigated the roles of the frequency of the root morpheme and the frequency of the whole word for a particular type of suffixed word in Korean in which the suffixed word can be thought of as a phrase (e.g., grandson-with). In both experiments, sentence frames were constructed so that they could have one of two target words that varied on frequency characteristics in the same location in the sentence. In Experiment 1, the frequency of the root morpheme was varied with the frequency of the word controlled, and in Experiment 2, the frequency of the word was varied with the frequency of the root morpheme controlled. Word frequency had a significant effect on fixation times, whereas root morpheme frequency did not. The results were surprising as native Korean speakers view the root morpheme as the “word” (analogous to how English readers would view a noun followed by a prepositional phrase).     

Evidence for a non-linguistic distinction between singular and plural sets in rhesus monkeys

Set representations are explicitly expressed in natural language. For example, many languages distinguish between sets and subsets (all vs. some), as well as between singular and plural sets (a cat vs. some cats). Three experiments explored the hypothesis that these representations are language specific, and thus absent from the conceptual resources of non-linguistic animals. We found that rhesus monkeys spontaneously discriminate sets based on a conceptual singular-plural distinction. Under conditions that do not elicit comparisons based on approximate magnitudes or one-to-one correspondence, rhesus monkeys distinguished between singular and plural sets (1 vs. 2 and 1 vs. 5), but not between two plural sets (2 vs. 3, 2 vs. 4, and 2 vs. 5). These results suggest that set-relational distinctions are not a privileged part of natural language, and may have evolved in non-linguistic species to support domain general quantitative computations.     

Hemispheric specialization for spatial frequency processing in the analysis of natural scenes

Experimental data coming from visual cognitive sciences suggest that visual analysis starts with a parallel extraction of different visual attributes at different scales/frequencies. Neuropsychological and functional imagery data have suggested that each hemisphere (at the level of temporo-parietal junctions-TPJ) could play a key role in spatial frequency processing: The right TPJ should predominantly be involved in low spatial frequency (LFs) analysis and the left TPJ in high spatial frequency (HFs) analysis. Nevertheless, this functional hypothesis had been inferred from data obtained when using the hierarchical form paradigm, without any explicit spatial frequency manipulation per se. The aims of this research are (i) to investigate, in healthy subjects, the hemispheric asymmetry hypothesis with an explicit manipulation of spatial frequencies of natural scenes and (ii) to examine whether the 'precedence effect' (the relative rapidity of LFs and HFs processing) depends on the visual field of scene presentation or not. For this purpose, participants were to identify either non-filtered or LFs and HFs filtered target scene displayed either in the left, central, or right visual field. Results showed a hemispheric specialization for spatial frequency processing and different 'precedence effects' depending on the visual field of presentation.     

Control of responding during stimuli that precede transitions in reinforcement frequency

Pigeons' responses were reinforced on a variant of a mixed variable-interval extinction schedule of reinforcement in which the transition to the higher reinforcement rate was signaled by a trace stimulus projected on the response key prior to the onset of the component correlated with food delivery. In the first of two experiments, the duration of the trace stimulus preceding the component correlated with food delivery was varied from 1.5 to 50.0 s and in the second experiment, the reinforcement frequency in the same component was varied from 10 to 60 reinforcers per hour. Pigeons pecked at the trace stimulus preceding the onset of the component correlated with food delivery even though responding was not reinforced in its presence and only one of the changes in reinforcement rate (i.e., from extinction to reinforcement) was signaled. The rate of pecking during the trace stimulus was a function of its duration but not of the reinforcement frequency in the following component. Higher rates generally occurred at the shorter trace-stimulus durations. Component responding following the offset of the trace stimulus was under discriminative control of the trace stimulus whether or not responding occurred in the presence of the trace stimulus.     

The processing of spatial frequency and orientation information

Three identification experiments were completed to disambiguate the associations between spatial frequency and orientation information at the sensory, decisional, and response levels. The stimuli were gratings generated by crossing four levels each of spatial frequency and orientation. In Experiment 1, the subjects made a single identification response to the stimuli. In Experiment 2, two identification responses were made, one for the spatial frequency component and the other for the orientation component. In Experiment 3, the subjects identified either the spatial frequency or the orientation component in any block of trials. The data were confusion matrices, and an information-transmission approach was used to investigate the interactions in the system. The results show that although there were sensory associations, there were no interactions at the decisional level. Performance parity was found: there was no significant difference between the single- and double-judgment paradigms in terms of information transmitted. Overall, the results suggest that although spatial frequency and orientation information is coded jointly at the sensory level, subsequent processing is independent, with each dimension drawing upon different attentional resources.