Dichotic listening and left-right confusion

The present study examined the relationship between individual differences in dichotic listening (DL) and the susceptibility to left-right confusion (LRC). Thirty-six men and 59 women completed a consonant-vowel DL test, a behavioral LRC task, and an LRC self-rating questionnaire. Significant negative correlations between overall DL accuracy and LRC rates in men (behavioral task) and self-ratings in women, indicated that the more participants struggled with left-right discrimination, the fewer DL syllables they reported correctly. However, there was no relationship between LRC and the typical right ear advantage. Thus, there is a sex- and task-dependent relationship between LRC and overall DL accuracy, but not between LRC and ear asymmetry. It is concluded that (a) atypical ear asymmetries, as in certain clinical populations, cannot be explained by associated deficits in left-right discrimination, and (b) LRC can negatively affect task performance, even when participants do not have to make explicit "left" versus "right" decisions.     

Dichotic temporal interactions: Fusion and temporal order

Attention, Perception, & Psychophysics - Several phenomena are associated with a monotonic increase in interaural temporal asymmetry (Δt) of equally intense auditory stimuli:...     

Dichotic listening with Chinese and English tasks

In this dichotic listening study, monosyllabic tasks were conducted in both English and Chinese to evaluate (1) the effects of processing two acoustically different languages and (2) the effects of bilingualism. One subject group included 28 bilingual speakers of English and Chinese, and a second group in cluded 29 monolingual English speakers. Three pairs of monosyllabic words were presented such that each ear received a different word at the same time. Twenty such sets in both languages were presented, with recall order irrelevant. The results show that the monolingual English subjects demonstrated a significant right ear advantage when identifying English words dichotically, suggesting a left hemisphere processing component. However, there was no ear effect when the English-Chinese speakers performed the dichotic listening tasks in both Chinese and English. It appears that, with the acquisition of a second language, right ear dominance seems to be replaced by interhemispheric processing.I would like to express my deep appreciation to John Ryalls for his efforts in the preparation of this article. Thanks also go to Stuart Davis, Steven Chin, Sven Anderson, David Pisoni, and two anonymous reviewers for their critical comments on previous drafts.     

Dichotic listening ear asymmetry: Patterns of longitudinal development

Dichotic listening research with children has continued to be prevalent although numerous authors have described both theoretical and methodological limitations with traditional dichotic listening free-recall paradigms. The present research adds to this growing skepticism by reanalyzing two major longitudinal studies of children's ear asymmetries. These two studies, based in different countries (United States, Holland), utilized highly similar paradigms (free-recall digits), subjects (males), and age levels (kindergarten and second and fifth grade). The questions of ear advantage development, patterns of ear advantages, and the relationship between dichotic listening performance and reading skills are addressed from the multiple statistical methodologies represented in the literature. From these analyses, support for all of the major hypotheses regarding the developmental patterns of dichotic listening performances could be obtained from the same data samples. The use of traditional free-recall dichotic listening paradigms are not recommended for use with children. The implications for future research are discussed.     

Dichotic listening with forced attention in patients with temporal lobe epilepsy: significance of left hemisphere cognitive dysfunction

Fifty right-handed patients with focal temporal lobe epilepsy were administered a dichotic listening test with consonant-vowel syllables under non-forced, forced right and forced left attention conditions, and a neuropsychological test battery. Dichotic listening performance was compared in subgroups with and without left hemisphere cognitive dysfunction, measured by the test battery, and in subgroups with left and right temporal epileptic focus. Left hemisphere cognitive dysfunction led to more correct responses to left ear stimuli in all three attention conditions, and fewer correct responses to right ear stimuli in the non-forced attention condition. This was probably caused by basic left hemisphere perceptual dysfunction. Dichotic listening was less affected by a left-sided epileptic focus than by left hemisphere cognitive dysfunction. General cognitive functioning influenced dichotic listening performance stronger in forced than in non-forced attention conditions. Larger cerebral networks were probably involved in the forced attention conditions due to the emphasis on conscious effort.     

Dichotic listening performance in subtypes of developmental dyslexia and a left temporal lobe brain tumor contrast group.

This study examined dichotic listening performance in three subtypes of developmental dyslexia and in children with left temporal lobe brain tumors (clinical contrast group). Each child was administered a free-recall CV syllable dichotic paradigm (30 pairs). Analysis of variance and Tukey-HSD pairwise follow-up comparison indicated that the dichotic listening performance of the left temporal lobe brain tumor contrast group (strong LEA/right ear suppression) was significantly different from those of the visual-spatial/dyseidetic (strong REA/left ear depression) and mixed (moderate REA/bilateral ear suppression) dyslexic subtypes. The language disorder/dysphonetic dyslexic subtype demonstrated a REA with right ear depression. Closer inspection of the individual performances of the language disorder/dysphonetic dyslexic subtype revealed a bimodal distribution with 12 subjects demonstrating a strong LEA/right ear suppression and 8 subjects exhibiting a strong REA/left ear depression. These results lend support for the contention that the dyslexic population is heterogeneous in nature with each subgroup exhibiting (1) a distinct neuropsychological test profile and reading pattern and (2) a pattern of performance on the dichotic listening task which is consistent with what would be expected based upon the pattern of dysfunction exhibited on neuropsychological evaluation.     

Dichotic listening performance and writing posture in right- and left-handers

Right-handers and left-handers with the inverted (IN) and noninverted (NI) writing posture were tested on a dichotic consonant-vowel listening task and on two motor tasks (hand strength and speed of tapping). The results failed to show the differences between IN and NI right-handers reported by S. M. Tapley and M. P. Bryden (1983, Neuropsychologia, 21, 129-138) and there were no significant handedness x writing posture x ear interactions. A significant interaction between dichotic listening performance and writing posture was found; NI right-handers and IN left-handers had more correct responses and fewer intrusions than IN right-handers and NI left-handers. Left-handers and right-handers were found to have a right ear advantage (REA) in the dichotic listening task but left-handers had relatively smaller left/right differences in all of the performance measures. Sample characteristics suggest that there are more IN male right-handers than IN female right-handers.     

Dichotic listening in children: age-related changes in direction and magnitude of ear advantage

Children between the ages of 5 and 12 years were tested with dichotic listening tests utilizing single syllable words and random presentations of digits. They produced a higher prevalence of left ear dominance than expected, especially among right-handed children when tested with words. Whether more children demonstrate the LEA because of right hemisphere dominance for language or because there is less stability in ear advantage direction at younger ages cannot be fully resolved by this study. When ear advantages were measured by subtracting each child's lower score from the higher score without regard to right or left direction, an age-related trend toward lower measures of ear advantage was evident. This trend was greater for dichotic words than for dichotic digits. Structural factors that may be related to these results and possible influences of attention and verbal workload on the two kinds of dichotic stimuli are discussed.     

Dichotic listening and otoacoustic emissions: shared variance between cochlear function and dichotic listening performance in adults with normal hearing

The present study investigated a possible connection between speech processing and cochlear function. Twenty-two subjects with age range from 18 to 39, balanced for gender with normal hearing and without any known neurological condition, were tested with the dichotic listening (DL) test, in which listeners were asked to identify CV-syllables in a nonforced, and also attention-right, and attention-left condition. Transient evoked otoacoustic emissions (TEOAEs) were recorded for both ears, with and without the presentation of contralateral broadband noise. The main finding was a strong negative correlation between language laterality as measured with the dichotic listening task and of the TEOAE responses. The findings support a hypothesis of shared variance between central and peripheral auditory lateralities, and contribute to the attentional theory of auditory lateralization. The results have implications for the understanding of the cortico-fugal efferent control of cochlear activity.     

Dichotic listening performances in the follow-up of Landau and Kleffner syndrome

Abstract

In the follow-up study of 4 children with acquired epileptic aphasia or Landau and Kleffner syndrome, dichotic listening studies evidenced a unilateral ear extinction. In the four cases, the dichotic extinction was contralateral to the temporal cortex involved in the generation of epileptic discharges during the active period of epilepsy. This pattern of dichotic performances persisted several years after the complete recovery from epilepsy and EEG normalization. The long-lasting dichotic extinction revealed a permanent dysfunction in the temporal auditory system that may be a consequence of the presence of an active epileptogenic focus during the critical period of functional differentiation of the temporal cortex.     

Dichotic interactions of speech sounds and phonetic feature processing

Identification of CV syllables was studied in a backward masking paradigm in order to examine two types of interactions observed between dichotically presented speech sounds: the feature sharing effect and the lag effect. Pairs of syllables differed in the consonant, the vowel, and their relative times of onset. Interference between the two dichotic inputs was observed primarily for pairs which contrasted on voicing. Performance on pairs that shared voicing remained excellent under all three conditions. The results suggest that the interference underlying the lag effect and the feature sharing effect for voicing occur before phonetic analysis where both auditory inputs interact.     

Picking up speed in understanding: Speech processing efficiency and vocabulary growth across the 2nd year

To explore how online speech processing efficiency relates to vocabulary growth in the 2nd year, the authors longitudinally observed 59 English-learning children at 15, 18, 21, and 25 months as they looked at pictures while listening to speech naming one of the pictures. The time course of eye movements in response to speech revealed significant increases in the efficiency of comprehension over this period. Further, speed and accuracy in spoken word recognition at 25 months were correlated with measures of lexical and grammatical development from 12 to 25 months. Analyses of growth curves showed that children who were faster and more accurate in online comprehension at 25 months were those who showed faster and more accelerated growth in expressive vocabulary across the 2nd year.     

Dichotic listening,executive functions and grey matter cortical volume in patients with schizophrenia and healthy controls

Schizophrenia is characterized by cognitive impairment, especially in relation to executive functions. Brain structural abnormalities are also often seen in schizophrenia although little is known of the relationship between cognitive impairment and structural brain changes. Our aim was therefore to investigate this relationship further using MRI and a dichotic listening (DL) task with simple speech sounds and with instructions to focus attention and report only from the left or right ear stimulus. When instructed to focus attention on the left ear syllable a cognitive conflict is induced requiring the allocation of executive resources to be resolved. Grey matter (GM) volume was measured with MRI from four volumes of interests (VOIs), left and right frontal and temporal cortex, respectively, and correlated with DL performance. The results showed significant differences between the groups in their ability to focus attention on and report the left ear stimulus, which was accompanied by reduced GM volume in the left frontal and right temporal lobe VOIs. There was also a significant positive correlation between left frontal GM volume and performance on the DL task, for the groups combined. The results did not support a conclusion that an impairment in cognitive function in schizophrenia was driven by an corresponding impairment in brain structure, since there were no significant correlations when the groups were analyzed separately. It is however concluded that patients with schizophrenia are impaired in executive functions and that they also show reduced GM volumes in left frontal and right temporal lobe areas, compared to healthy controls.     

The generation of temporal and melodic expectancies during musical listening

When listening to a melody, we are often able to anticipate not onlywhat tonal intervals will occur next but alsowhen in time these will appear. The experiments reported here were carried out to investigate what types of structural relations support the generation of temporal expectancies in the context of a melody recognition task. The strategy was to present subjects with a set of folk tunes in which temporal accents (i.e., notes with a prolonged duration) always occurred in the first half of a melody, so that expectancies, if generated, could carry over to an isochronous sequence of notes in the latter half ofthe melody. The ability to detect deviant pitch changes in the final variation as a function of rhythmic context was then evaluated. Accuracy and reaction time data from Experiment 1 indicated that expectancy formation jointly depends on an invariant periodicity of temporal accentuation and the attentional highlighting ofcertain melodic relations (i.e., phrase ending points). In Experiment 2, once these joint expectancies were generated, the temporal dimension had a greater facilitating effectupon melody recognition than did the melodic one. These results are discussed in terms of their implications for the perceptual processing of musical events.     

The relationship between puberty and social emotion processing

The social brain undergoes developmental change during adolescence, and pubertal hormones are hypothesized to contribute to this development. We used fMRI to explore how pubertal indicators (salivary concentrations of testosterone, oestradiol and DHEA; pubertal stage; menarcheal status) relate to brain activity during a social emotion task. Forty‐two females aged 11.1 to 13.7 years underwent fMRI scanning while reading scenarios pertaining either to social emotions, which require the representation of another person’s mental states, or to basic emotions, which do not. Pubertal stage and menarcheal status were used to assign girls to early or late puberty groups. Across the entire sample, the contrast between social versus basic emotion resulted in activity within the social brain network, including dorsomedial prefrontal cortex (DMPFC), the posterior superior temporal sulcus, and the anterior temporal cortex (ATC) in both hemispheres. Increased hormone levels (independent of age) were associated with higher left ATC activity during social emotion processing. More advanced age (independent of hormone levels) was associated with lower DMPFC activity during social emotion processing. Our results suggest functionally dissociable effects of pubertal hormones and age on the adolescent social brain.     

The repressor personality and avoidant information processing: A dichotic listening study

The present research was designed to investigate the proposition that repressors, operationally defined by the conjunction of low anxiety and high defensiveness, are particularly adept at avoiding the processing of information when motivated to do so. Four groups of participants (nondefensive-low anxious, high anxious, repressors, and defensive-high anxious) were administered a dichotic listening task involving neutral or negative affective words presented in the unattended ear. Participants shadowed the material presented to the attended ear and simultaneously responded to a probe task presented on a video monitor. Results revealed that repressors made significantly fewer shadowing errors than high anxious and defensive-high anxious participants and marginally significantly fewer shadowing errors than low anxious participants for both neutral and negative words. High anxious participants, however, were later able to recognize the negative words that had been presented to the unattended ear at well above chance levels, whereas the recognition memory of repressors for such negative unattended words was at chance levels. In addition, repressors' responses to a postexperiment questionnaire indicated a significantly greater number of distracting thoughts during the experiment relative to other participants. Repressors, it seems, are indeed skillful at avoidant information processing and this capacity may well be related to the emotional memory deficits they have displayed in previous research.     

Verbal working memory and on-line syntactic processing: Evidence from self-paced listening

Two experiments investigated the relationship between performance on standard tests of verbal working-memory and the on-line construction of syntactic form. In Experiment 1, working-memory was measured in 100 college students on a version of the Daneman and Carpenter (1980) reading-span task, and online syntactic processing was assessed using a self-paced listening task with four sentence types. In Experiment 2, working-memory was measured in 48 college students on two versions of the reading-span task and two other tests of verbal working-memory, and on-line syntactic processing was assessed using the self-paced listening task with an additional sentence type. In both experiments, there was no relationship between working-memory capacity and the increase in processing time seen for the on-line construction of syntactic form for either syntactically more complex or syntactically simpler sentences. The results indicate that the capacity of the working-memory system that is measured by standard working-memory tests does not determine the efficiency of on-line syntactic processing. They are consistent with the view that the working-memory system used for parsing is at least partially separate from that measured by traditional measures of working-memory capacity.