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 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 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 pattern in conduction aphasia

This paper reports a finding of hemispheric brain asymmetry for speech in short-gestation infants (mean gestational age = 36 weeks). Using a new measure—degree of reduction in limb tremors following exposure to speech stimuli compared to two control groups, one hearing orchestral music, the other no patterned stimuli—we found that speech disproportionately affected right limb movements. It is not clear whether the effect is due to asymmetries in cortical or subcortical processing. This provides evidence against the notion that brain specialization for language functions necessarily appears over time; rather, specialization for some functions (e.g., speech reception) must be present at birth.     

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 and sleep deprivation: vigilance effects

Twelve sleep-deprived and 13 non-deprived Navy cadets were tested with the dichotic listening procedure for effects of sleep deprivation on hemispheric asymmetry and sustained attention. Consonant-vowel syllables were presented to the subjects in three different conditions, a divided (non-forced) attention condition, a forced right ear and a forced left ear attention condition. In the two forced attention conditions the subjects were instructed to focus attention only on the right or left ear stimulus. The results showed an expected right ear advantage for both groups during the non-forced and forced right attention conditions, indicating superior left hemisphere processing. During the forced left attention condition, the sleep-deprived subjects showed no ear advantage at all, while the non-deprived subjects showed an expected left ear advantage. The results are discussed within a theoretical framework of a dual process model, where sleep deprivation disrupts the ability to sustain attention, caused by a temporary failure of the right hemisphere's top-down (instruction-driven) processing to override the left hemisphere's bottom-up (stimulus-driven) processing.     

Dichotic listening in a child recovering from acquired aphasia

A right-handed 6-year-old boy with acquired aphasia of left-hemisphere origin was investigated with various dichotic listening tasks 8 and 13 months after onset of the symptoms. Total right ear extinction was found repeatedly using both numbers and words as stimuli. Furthermore, magnitude of right ear extinction was not amenable to modification through verbal training, but disappeared when words were presented to the child's right ear with simultaneous white noise to the left ear. The findings are discussed in terms of the plasticity of cerebral dominance during childhood.     

Dichotic listening in college students who report auditory hallucinations

College students were placed in 2 groups, hallucinators and nonhallucinators, on the basis of their responses to a verbal hallucinations questionnaire. Both groups were given a consonant-vowel version of a Dichotic Listening Test under 3 conditions: nonforced, forced-right, and forced-left. When hallucinators were instructed to attend to the left ear stimuli (forced-left condition), they had fewer correct responses to right ear syllables than did nonhallucinators. This resulted in a left ear advantage for hallucinators. When nonhallucinators were instructed to attend to the left ear, they maintained a right ear advantage. Results suggest that auditory hallucinations in college students are associated with differences in hemispheric functioning.     

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 in the recovery of aphasia after stroke

Three different dichotic listening tests were given to a group of aphasic patients at various stages of the recovery process. Results were different for each test and in the course of time fluent aphasics demonstrated a tendency to increase right ear preference while nonfluent aphasics showed an increase of left ear preference in the test of dichotic words. The importance of these findings to the understanding of recovery of function is discussed in terms of the role played by the right hemisphere.     

Dichotic listening during forced-attention in a patient with left hemispherectomy

A young left-handed girl with an extensive posttraumatic lesion in the left hemisphere was tested with dichotic listening (DL) under three different attentional instructions. The major aim of the study was to evaluate a structural vs attentional explanation for dichotic listening. As both her expressive and receptive language functions were intact after the lesion, it was assumed that the right hemisphere was the language-dominant one. In the free-report condition, she was free to divert attention to and to report from both ear inputs. In the forced-right condition, she was instructed to attend to and report only from the right ear input. In the forced-left condition, she was instructed to attend to and to report only from the left-ear input. Her performance was compared with data from a previously collected sample of normal left-handed females. Analysis showed that the patient, in contrast to the normal sample, revealed a complete right-ear extinction phenomenon, irrespective of attentional instruction. Furthermore, she showed superior correct reports from the left ear, compared with those of the normal sample, also irrespective of attentional instruction. It is concluded that these results support a structural, rather than attentional explanation for the right-ear advantage (REA) typically observed in dichotic listening. The utility of validating the dichotic listening technique on patients with brain lesions is discussed.     

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 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 listening following idiopathic precocious puberty: Speech processing capacity and temporal efficiency

Eleven right-handed adolescent females with a history of idiopathic precocious puberty (IPP) were compared to 11 pair-matched normal controls of similar maturational status. They were tested on a dichotic consonant-vowel (CV) discrimination task in which syllables were presented simultaneously to the two ears or with an interaural delay of 30 or 60 msec. The IPP and control groups did not differ: (1) in right-ear advantages; (2) in double-correct or total correct measures of accuracy; or (3) in "lag effects." The findings provide further evidence that timing of puberty--maturation rate--is not related to verbal ability or lateralization in adolescent females.     

Universality versus language-specificity in listening to running speech

Recognizing spoken language involves automatic activation of multiple candidate words. The process of selection between candidates is made more efficient by inhibition of embedded words (like egg in beg) that leave a portion of the input stranded (here, b). Results from European languages suggest that this inhibition occurs when consonants are stranded but not when syllables are stranded. The reason why leftover syllables do not lead to inhibition could be that in principle they might themselves be words; in European languages, a syllable can be a word. In Sesotho (a Bantu language), however, a single syllable cannot be a word. We report that in Sesotho, word recognition is inhibited by stranded consonants, but stranded monosyllables produce no more difficulty than stranded bisyllables (which could be Sesotho words). This finding suggests that the viability constraint which inhibits spurious embedded word candidates is not sensitive to language-specific word structure, but is universal.     

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.