Left Ear Accuracy Research Articles

EQUIVALENCE OF WORD TEST AND CONSONANT-VOWEL SYLLABLES TEST OF DICHOTIC LISTENING

Relevance. Development and improvement of methodological tools to solve scientific and practical problems is an important issue in modern neuropsychology. This study examines consonant-vowel (СV) syllable test and word test, considers their different functional orientation and shows relevance of the dichotic listening task development. For the first time in Russian neuropsychology the authors developed the dichotic listening consonant-vowel syllables test taking into account the phonetic features of the Russian language. Objective. Comparison of the equivalence of two dichotic listening tests: the word test that was first tested by B. S. Kotik and the two CV-syllable dichotic listening tests. Method. Two groups of respondents participated in the study. The first group of the participants (N = 88; M = 21.08; SD = 2.32) performed the word test and the first CV-syllable test. Participants of the second group (N = 44; M = 24.52; SD = 1.86) were presented with the word test and the second version of CV-syllable dichotic listening test. Results. The results confirmed the differences between the word test and the two CV-syllable dichotic listening tests. The differences and nonequivalence of the word test and the CV-syllable tests in laterality index (LI) and productivity coefficients (general productivity, right- and left-ear accuracy scores) are amplified as the stimulus material of CV-syllable dichotic listening is improved and modified. The increase of the load on working memory enhances right ear advantage (LI) and reduces performance with an increase in the influence of working memory on the results of dichotic listening. Conclusion. The study shows nonequivalence of the word test and the CV-syllable tests and their different functional orientation for the estimation of hemispheric specialization in audio-verbal domain.

The Role of Dichotic Listening Performance and Tasks of Executive Functions in Reading Impairment: A Discriminant Function Analysis

This study focused on the role of dichotic listening performance for the identification of reading impaired subtypes. Dichotic listening (DL), using verbal stimuli, has shown to be a valid measure of language lateralization. Usually, lateralization is estimated from the proportion of right ear over left ear accuracy during a free recall test procedure. However, it has been suggested that a more accurate estimate of laterality can be obtained by using a directed attention procedure. A sample of 43 reading disabled children of whom 18 showed signs of impaired language comprehension skills and 25 without language comprehension impairments, were compared to 20 age, and gender, matched controls on dichotic listening performance in both an unbiased free recall task and in a directed attention task using consonant-vowel syllables as dichotic stimuli. A laterality index was calculated for left and right ear stimuli reported during both the free recall condition and the attended ear-scores for the two directed attention conditions. Although both DL procedures yielded significant group differences, with a lower laterality score for the reading disabled compared to the controls, there was no main effect of DL-procedure or group × procedure interaction. Taken alone, DL performance could correctly classify 42% of the reading impaired samples, but together with other measures of executive functions, discriminant function analyses yielded 90.74% accuracy in classifying reading impaired children. The result indicates that DL together with tests of executive functions are valuable tools for assessment of reading impaired subjects.

Comment on delayed left-ear accuracy in dichotic listening.

Moulden and Persinger recently reported on the emergence of left-ear accuracy during childhood and adolescence. This commentary briefly discusses their findings with reference to previous studies that have reported on dichotic listening paradigms and, in particular, those in which a left-ear focus was used as a behavioral probe sensitive to developmental sex differences.

COMMENT ON DELAYED LEFT-EAR ACCURACY IN DICHOTIC LISTENING

Moulden and Persinger recently reported on the emergence of left-ear accuracy during childhood and adolescence. This commentary briefly discusses their findings with reference to previous studies that have reported on dichotic listening paradigms and, in particular, those in which a left-ear focus was used as a behavioral probe sensitive to developmental sex differences.

Delayed left ear accuracy during childhood and early adolescence as indicated by Roberts' Dichotic Word Listening Test.

A total of 200 girls and boys between the ages of 6 years and 15 years were administered Roberts' Dichotic Word Listening Test. A statistically significant relatively abrupt and maintained increase in left ear accuracy was noted after 9 years of age (eta = .55). Except for a mild improvement after 6 to 7 years of age, comparable changes were not observed for the right ear. The magnitude of the effect was not significantly diminished even after covariance for verbal fluency and semantic categorization. These results are compatible with the observations that myelination of the cerebral commissures and electroencephalographic phase relations of the right hemisphere achieve near-adult characteristics after 9 years of age. Boys displayed less accuracy for dichotic word listening, particularly for the left ear, compared to the girls eta = .20).

Incremental Improvement of Dichotic Left Ear Accuracy and Toe Gnosis Between 9 and 10 Years of Age: Implications for Maturation of a Portion of the Corpus Callosum and of the Sense of Self

Analyses of the data from 212 boys and girls, aged 7-14 years, demonstrated a relatively abrupt and permanent decrease in the numbers of errors for dichotic (left ear) word listening and for toe gnosis after the ninth year. This pattern was not observed for right ear errors, finger gnosis, or indices of finger and foot agility. The results are compatible with the hypothesis that the final differentiation of the paracentral lobules and adjacent corpus callosum by the most distal portions of the Anterior Cerebral Artery occurs around 9 or 10 years of age. Implications for the development of the sense of self, enhanced apprehension, and "the sense of a presence" are discussed.

Incremental Improvement of Dichotic Left Ear Accuracy and Toe Gnosis Between 9 and 10 Years of Age: Implications for Maturation of a Portion of the Corpus Callosum and of the Sense of Self

Analyses of the data from 212 boys and girls, aged 7-14 years, demonstrated a relatively abrupt and permanent decrease in the numbers of errors for dichotic (left ear) word listening and for toe gnosis after the ninth year. This pattern was not observed for right ear errors, finger gnosis, or indices of finger and foot agility. The results are compatible with the hypothesis that the final differentiation of the paracentral lobules and adjacent corpus callosum by the most distal portions of the Anterior Cerebral Artery occurs around 9 or 10 years of age. Implications for the development of the sense of self, enhanced apprehension, and "the sense of a presence" are discussed.

Do tricyclic responders have different brain laterality?

A previous study showed that depressed patients who improved with tricyclic antidepressant medication had dichotic complex tones test results suggesting right-hemisphere dysfunction relative to nonresponders and controls (G. E. Bruder et al., 1990). A new sample of 68 depressed patients completed dichotic consonant-vowel (CV) and complex tones (CT) tests and then were treated with imipramine or placebo. A significant Ear x Test x Treatment x Response interaction was accounted for by significantly poorer left-ear accuracy for CVs among imipramine responders compared with nonresponders, placebo responders, and controls. CV left-ear accuracy was also significantly greater among placebo responders than placebo nonresponders and controls. The results only partially replicate the prior study in that evidence of right-hemisphere dysfunction in tricyclic responders was seen for the CV test but not the CT test.

Dichotic-listening measures of brain laterality in mania.

Dichotic syllable and complex tone tests were used to compare performance asymmetries in manic patients (n = 35) with normal controls (n = 26) and to determine whether there were changes in laterality with remission of the manic state. Relationships of performance asymmetries to treatment outcome and symptom features were also examined. Compared with normal controls, manic patients showed overall poorer accuracy, particularly for complex tones presented to the left ear, and they failed to show the normal left-ear (right-hemisphere) advantage for complex tones. Abnormal laterality for complex tones was present in patients who later responded to treatment but not in nonresponders. In the euthymic state, patients showed improved left-ear accuracy for complex tones and more normal perceptual asymmetry. These findings suggest that mania is associated with a decrement in right-hemisphere processing of complex tonal information.

Neuropsychological performance in chronic schizophrenia in response to neuroleptic dose reduction

The effect of 80%–90% neuroleptic dose reductions on neuropsychological function in schizophrenic and schizoaffective patients was examined in a prospective study. A neuropsychological battery was administered in the week prior to neuroleptic reduction followed by retesting at least 6 weeks postreduction. Patients were retested only if they did not relapse after reduction. The design allowed neuropsychological changes due to neuroleptic medications to be assessed independently of general clinical change. Neuropsychological performance was generally stable and unchanging. However, there was a trend toward significant improvement on a dichotic digits task based in improvement in left ear accuracy. Negative symptoms diminished after reduction. Compared with a normal control group, schizophrenics' initial laterality index showed a significantly exaggerated right ear advantage (REA); after reduction, the REA was no longer different from controls. The findings indicate that neuropsychological changes in a small sample of older nonrelapsing chronic schizophrenics are modest. The data suggest that neuroleptics may impair right hemisphere functions in some patients.

Lateral specialization and social-verbal development in preschool children

Forty-two 2 built1 2 - to 5 built1 2 -year-old children's social and verbal behaviors were observed during free play in a preschool. A test measuring lateral specialization of verbal function and a standardized psychometric test of verbal ability were also administered. Analysis of variance indicated that the right ear (left hemisphere) is predominant in processing verbal stimuli in children as young as 2 built1 2 . Multiple regression analyses revealed significant relations between the right ear accuracy score for dichotically presented verbal stimuli and both psychometrically measured verbal ability and a social-verbal factor score derived from play behavior. After the increase related to age was statistically partialled out from both verbal ability and social-verbal scores, verbal expression, length of verbal utterances, time spent in conversation, and peer social interactions increased and parallel play decreased as a function of right ear (left hemisphere) accuracy for verbal stimuli. The relationship between left ear (right hemisphere) accuracy scores for verbal stimuli and social-verbal behavior, however, was not linear. Very high and very low levels of left ear recall predicted an increase in the frequency of parallel play and low social-verbal behavior while moderate levels of left ear accuracy scores predicted the reverse.

Relationship of ear specialization to degree of task difficulty, sex, and lateral preference.

Children in Grades 2 and 6 nested in age, sex, and lateral-preference groups were administered two dichotic listening tests (digit and environmental sound). There was a right-ear advantage for verbal stimuli which did not increase with age, supporting the invariance models of the development of verbal laterality past 5 to 6 years of age. The percentage of left-ear accuracy for verbal stimuli relative to the right ear decreased with task difficulty. Girls were more accurate than boys when recalling verbal stimuli and the older boys were more accurate than the other children when identifying environmental sounds. In recalling nonverbal stimuli, boys showed a left-ear advantage and out-performed girls, who showed a right-ear advantage. The sex difference in ear advantage increased with task difficulty. There was an over-all increase in accuracy with age when identifying both verbal and nonverbal stimuli with the exception of the ambidextrous children, who demonstrated low accuracy scores for the environmental sound stimuli across age groups.

Cerebral dominance for pitch contrasts in tone language speakers and in musically untrained and trained English speakers

Speakers of a tone language, Thai, recognize pitch contrasts which are linguistically significant in their language better at the right ear in a dichotic listening task, but show no ear advantage for the same pitch contrasts occurring in a nonlinguistic context. American English speakers, divided into musically untrained and trained groups, show no ear advantage for those same pitch contrasts. The only effect of musical training is an enhancement of left ear accuracy for pitch contrast recognition.