Unilateral nostril breathing influences lateralized cognitive performance

Relative nostril efficiency (nasal cycle) is related to hemispheric EEG differences and performance on cognitive tasks. We investigated how unilateral forced nostril breathing influences spatial and verbal performance. Right-handed males and females performed both tasks under either left-nostril, right-nostril, or free-breathing conditions. Unilateral breathing affects performance differently in males and females. It influences male performance ipsilaterally on both tasks: Their spatial performance is better during right-nostril breathing, and their verbal performance is better during left-nostril breathing. Unilateral breathing influences female performance contralaterally, but only on the spatial task: Their spatial performance is better during left-nostril breathing. These differences within and between sexes may exist because unilateral nostril breathing differentially activates the two hemispheres and thereby facilitates performance, or because attempts of the brain to control the nasal cycle unilaterally interfere with performance.     

Hemispheric emotional asymmetry in a dichotic listening task.

In a dichotic listening experiment white noise was played to one ear and either music or poetry to the other ear. Subjects rated the stimuli on each of three dimensions. The results showed that both music poetry were judged as more pleasant when heard at the left than the right ear. In addition the music, but not the poetry, was perceived as more soothing at the left ear. The findings are discussed in relation to other indications in the literature that left and right cerebral hemispheres differ in their emotional make-up.     

Unilateral nostril breathing in intraocular pressure of right-handed healthy subjects

The effects of unilateral forced nostril breathing on the intraocular pressures of right and left eyes was studied in 24 male and 26 female right-handed adults. In men, the forced breathing through both the right and left nostrils significantly decreased the intraocular pressures of both right and left eyes. For women, the forced breathing through right nostril did not affect the intraocular pressures of right and left eyes, and the forced breathing through left nostril also had no effect on the intraocular pressure of right eye, although it decreased the intraocular pressure of left eye significantly. These results show that unilateral forced nostril breathing decreases intraocular pressure especially in men, perhaps increasing sympathetic nervous system activity.     

The role of spatial complexity in the perception of speech and pure tones in dichotic listening

Ear advantages for CV syllables were determined for 28 right-handed individuals in a target monitoring dichotic task. In addition, ear dominance for dichotically presented tones was determined when the frequency difference of the two tones was small compared to the center frequency and when the frequency difference of the tones was larger. On all three tasks, subjects provided subjective separability ratings as measures of the spatial complexity of the dichotic stimuli. The results indicated a robust right ear advantage (REA) for the CV syllables and a left ear dominance on the two tone tasks, with a significant shift toward right ear dominance when the frequency difference of the tones was large. Although separability ratings for the group data indicated an increase in the perceived spatial separation of the components of the tone complex across the two tone tasks, the separability judgment ratings and the ear dominance scores were not correlated for either tone task. A significant correlation, however, was evidenced between the laterality measure for speech and the judgment of separability, indicating that a REA of increased magnitude is associated with more clearly localized and spatially separate speech sounds. Finally, the dominance scores on the two tone tasks were uncorrelated with the laterality measures of the speech task, whereas the scores on the tone tasks were highly correlated. The results suggest that spatial complexity does play a role in the emergence of the REA for speech. However, the failure to find a relationship between speech and nonspeech tasks suggest that all perceptual asymmetries observed with dichotic stimuli cannot be accounted for by a single theoretical explanation.     

Review of some sex-related effects of forced unilateral nostril breathing on the autonomic nervous system

Sex-related effects of forced unilateral nostril breathing on the autonomic nervous system are considered. Recent studies described the effects of such breathing on autonomic activity as sex-specific as in prior studies.     

The effects of attention on ear advantages in dichotic listening to words and affects

This study examined the effects of attention on ear advantages using dichotic listening to words and affects, a focused-attention paradigm. We compared the mixed condition, in which attention is switched between the ears in each trial, to the blocked condition, in which attention is directed to one ear for an entire block of trials. Results showed a decreased right ear advantage for word processing only in the mixed condition and an increased left ear advantage for emotion processing in both attention conditions for hits index. The mixed condition showed smaller laterality effects than the blocked condition for words with respect to hits index, while increasing right ear predominance for intrusions. The greater percentage of intrusions in the right ear for the word task and in the mixed condition suggests that the right ear (left hemisphere) is most vulnerable to attention switching. We posit that the attention manipulation has a greater effect on word processing than on emotion processing and propose that ear advantages reflect a combination of the effects of attentional and structural constraints on lateralisation.     

Forced unilateral nostril breathing: a technique that affects brain hemisphericity and autonomic activity

Asymmetrical shoulder, thoracic and buttock pressure affect ipsilateral nasal resistance, autonomic tone, and hemisphericity. This factor must be taken into consideration when conducting psychological experimentation, and, in fact, may have confounded much prior research.     

Hemispheric laterality and dissociative tendencies: differences in emotional processing in a dichotic listening task

The present work investigates whether the hemispheric processing of both verbal and emotional stimuli, studied by means of a dichotic listening task, differs between normal high and low dissociators as assessed by the Dissociative Experiences Scale (DES; Bernstein & Putnam (1986). Development, reliability and validity of a dissociation scale. Journal of Nervous and Mental Disease, 174(2), 727-735). Two groups of subjects (50 high and 50 low dissociators), participated in the experiment. The task consisted in identifying both verbal and emotional stimulus-targets, respectively, on successive sessions. Reaction time and response accuracy were registered and analysed using ANOVA (Analysis of Variance). The interaction between stimuli (verbal, emotional), channel (right ear, left ear), and dissociation level (high, low) reached statistical significance in terms of accuracy measures (d': F(1,98)=4.75; p<.05). Both high and low dissociators exhibited the expected right ear advantage (REA effect) on verbal targets. On the other hand, whereas low dissociators exhibited the expected left ear advantage (LEA effect) on emotional targets, high dissociators failed to follow this typical pattern of hemispheric asymmetry: both hemispheres exhibited similar performances. These results confirm the hypothesis that dissociation is related to changes in hemispheric processing, specifically of emotional information.     

A right-ear advantage for dichotic listening in bilingual children

A dichotic listening task was administered to two groups of right-handed Hispanic children enrolled in bilingual education classes. The younger group's mean age was 9:6, the older group's was 13:6. Two dichotic tapes were used, one in English, one in Spanish, consisting of 60 pairs of words per tape. The words were comparable across languages in terms of frequency, grammatical function, and phonetic composition. The results showed clear and equal right-ear advantages for both groups of subjects and for both languages. As expected, older children scored higher than younger ones, and performance on Spanish was better than on English. Neither of these effects interacted with the ear advantage, however. Ear difference scores did not correlate with proficiency in the second language (as measured by performance on the English tape), but there was a significant correlation (r = .58) between the degree of asymmetry in the two languages. These findings indicate that the left hemisphere is primarily (and equally) involved in processing both languages of bilinguals, and that this pattern appears to remain stable in development.     

Hemispheric specialization for voice recognition: evidence from dichotic listening

To measure lateralization of voice recognition abilities in normal subjects, listeners identified both the speaker (a famous male) and the word spoken on each trial in a dichotic listening paradigm. The voice identification task resulted in a zero ear advantage, which differed significantly from the significant right ear advantage found for word identification. This suggests that voice and word information, although carried in the same auditory signal, engage different cerebral mechanisms.     

Biasing thematic contexts for ambiguous sentences in a dichotic listening experiment

In an experiment derived from Lackner and Garrett (1972) 80 subjects were given a dichotic listening task where they were presented with ambiguous sentences to an attended ear and disambiguating sentences to the other, unattended, ear. Each of the sentences was preceded by a thematic context that was biased for one meaning of the ambiguous sentence. In one-half of the instances the contexts biased a meaning consistent with that of the disambiguating sentence, and in the remaining one-half they biased the meaning of the ambiguous sentence in a way that was inconsistent with the meaning of the ambiguous sentence. The meanings of the ambiguous sentences the subjects perceived tended to be those that were consistent with the biasing context, even when that meaning was inconsistent with the meaning of the disambiguating sentence. Therefore, when ambiguous sentences are preceded by a thematic context, a single-reading explanation of the processing is more appropriate than a multiple-reading explanation.     

A method for the preparation of audio tapes for dichotic listening research

A simple method for producing audio tapes with temporally synchronized messages is described. The duration and spacing of words can be precisely controlled. This method requires a minimum of elaborate equipment, yet synchronization is very accurate with highly intelligible speech.     

Longitudinal dichotic listening patterns for aphasic patients : I. Description of recovery curves

Aphasic patients were given digit and noun dichotic listening tests at monthly intervals during the first 6 months postonset of left hemisphere ischemic infarctions. Significant changes in performance were observed that consisted of parallel increases in scores for the two ears, and thus did not support the hypothesis that language recovery is mediated by transfer of language dominance from the left to the right hemisphere. Reliable differences also were noted between performance on the two tests. RE scores accounted for most of the variance among patients in performance on dichotic tests and, as such, appeared to be the best measure for characterizing individual differences.     

Selective listening and threshold for tones appearing on a relevant and on an irrelevant input channel

Threshold scores for tones appearing on shadowed and on nonshadowed messages were obtained in order to test whether input presented on an irrelevant channel is attenuated when Ss attend to another channel. Comparisons were made between threshold scores obtained for each ear, when Ss shadowed messages appearing on that ear and when Ss shadowed messages appearing on the contralateral ear. The threshold scores in the two conditions were highly similar. Data are evaluated in the context of auditory target detection, with targets identified by their verbal content vs their physical characteristics.     

Properties of feature detectors for speech: Evidence from the effects of selective adaptation on dichotic listening

Two selective adaptation experiments were conducted in order to investigate certain properties of feature detector systems sensitive to the information underlying the voicing distinction (Experiment I) and the place of articulation distinction (Experiment II). The experimental paradigm combined binaural adaptation with a dichotic testing procedure. The stimuli were nonboundary, good exemplars of the respective phonetic categories. In both experiments, there was a systematic shift in performance following adaptation on those trials on which the stimulus in one ear had the adapted feature value and the stimulus in the other ear had the unadapted feature value. On these trials, the adapted feature value was relatively less effective in competing for processing with the unadapted value in the opposing ear (compared to preadaptation performance). Since these results were obtained using nonboundary stimuli, it was argued that (1) adaptation affects the relevant detector along its range of operation or sensitivity, and nof simply at the phonetic boundary, and that (2) information regarding the relative output level of the detector, as well as which detector was more strongly excited, must be available at the site of interaction of the two stimuli.

     

Predictors of therapeutic response to treatments for depression: a review of electrophysiologic and dichotic listening studies

There are few clinical or biologic predictors of response to treatments for depression. This article reviews growing evidence that electrophysiologic and neurocognitive measures of brain function may be of value as predictors of therapeutic response to antidepressants. Initial studies using dichotic listening, quantitative electroencephalography, or event-related brain potential measures have found differences between treatment responsive and nonresponsive subgroups of depressed patients. The neurophysiologic basis for these differences and the potential clinical utility of electrophysiologic and dichotic predictors of treatment outcome remain to be determined in future studies.     

Use of a statistical significance criterion in drawing inferences about hemispheric dominance for language function from dichotic listening data

A dichotic listening test (composed of VCV nonsense syllables) was administered to 31 right-handed subjects. A χ² statistical significance criterion was then applied to the resulting ear differences in subjects. Fifteen subjects had ear differences significant at the p < .10 levels. Of these, 14 had right-ear advantages, an incidence consistent with the incidence of left-hemisphere language dominance derived from neurological data. Incidence for the total group of 31 subjects, however, showed the overabundance of left-ear-superior protocols typical of studies that report ear-dominance scores with no statistical criterion.     

"Binaural rivalry": dichotic listening as a tool for the investigation of the neural correlate of consciousness

Since about two decades neuroscientists have systematically faced the problem of consciousness: the aim is to discover the neural activity specifically related to conscious perceptions, i.e. the biological properties of what philosophers call qualia. In this view, a neural correlate of consciousness (NCC) is a precise pattern of brain activity that specifically accompanies a particular conscious experience. Almost all studies aimed at investigating the NCC have been carried out in the visual system. One of the most promising paradigms is based on sensory stimuli which elicit bistable percepts, as they allow to decouple subjective perception from the characteristics of the physical stimulation. Such kind of perception can be produced in the visual modality by using particular images (e.g. Rubin's vase/face figure) or by presenting two dissimilar stimuli separately to the two eyes (binocular rivalry). The stimuli compete for perceptual dominance and each image is visible in turn for a few seconds, while the other is suppressed. The use of this methodology has led to important findings concerning visual consciousness, which are briefly discussed. For the investigation of auditory consciousness, a similar stimulation paradigm can be achieved by using dichotic listening, consisting in two different stimuli presented each to one ear, which compete for perception (binaural rivalry). The principal aim of the present mini-review is to discuss the few contributes facing the issue of auditory consciousness and to advance the use of dichotic listening and binaural rivalry as valid tools for its investigation.