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 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.     

Interictal and postictal performances on dichotic listening test in children with focal epilepsy

Dichotic listening test (DL) is an important tool to disclose speech dominance in healthy subjects and in clinical cases. The aim of this study was to probe if focal epilepsy in children reveals a corresponding suppression of the ear reports contralateral to seizure onset site. Thus, 15 children and adolescents with clinically and electroencephalographically diagnosed focal epilepsy selected for left-hemisphere speech dominance without mental retardation were compared to matched controls according to age, gender, IQ and handedness. All children were assessed with DL for three times: Interictally (t(0)), postictally 5' (t(1)) and 1h (t(2)). At t(0), all groups revealed a right ear advantage (REA), indicating a left-hemisphere speech dominance. There was a continuous increase in right correct score (REC) over the trials for normal controls. Five minutes postictally, there was an abrupt decrease in REC with a sustained left ear correct score (LEC) for children with epilepsy, independent of which side suffered from seizures. This effect was maintained even after 1h. Thus, in children with left-hemisphere speech dominance the epileptic discharges caused a suppression of REC regardless of origin. The seizures may have a prolonged impact on attention and auditory perception for a considerable time after consciousness has been regained.     

Right visual field advantage for perceived contrast: correlation with an auditory bias and handedness

Studies have suggested that supramodal attentional resources are biased rightward due to asymmetric spatial fields of the two hemispheres. This bias has been observed especially in right-handed subjects. We presented left and right-handed subjects with brief uniform grey visual stimuli in either the left or right visual hemifield. Consistent with the proposed asymmetry in attentional resources, right-handed subjects estimated right hemifield targets as having a higher contrast than physically identical stimuli presented in the left hemifield. Left-handed participants did not show a systematic rightward or leftward bias. However, the group of left-handed participants also took part in a dichotic listening experiment whose results showed that visual bias score correlated positively with ear-advantage in dichotic listening. Our results are consistent with the view that supramodal processing resources are biased towards the right hemispace, and that this bias is influenced by handedness.     

Ear advantage and consonance of dichotic pitch intervals in absolute-pitch possessors

Left-right asymmetry in the central processing of musical consonance was investigated by dichotic listening tasks. Two piano tones paired at various pitch intervals (1-11 semitones) were presented one note in each ear to twenty absolute-pitch possessors. As a result, a weak overall trend for left ear advantage (LEA) was found, as is characteristic of trained musicians. Second, pitches of dissonant intervals were more difficult to identify than those of consonant intervals. Finally, the LEA was greater with dissonant intervals than with consonant intervals. As the tones were dichotically presented, the results indicated that the central auditory system could distinguish between consonant and dissonant intervals without initial processing of pitch-pitch relations in the cochlea.     

Asymmetry and performance: toward a neurodevelopmental theory

Hemispheric asymmetry implies the existence of developmental influences that affect one hemisphere more than the other. However, those influences are poorly understood. One simple view is that asymmetry may exist because of a relationship between a mental process' degree of lateralization and how well it functions. Data scaling issues have largely prevented such investigations, but it is shown that scaling effects are minimized after correction for ceiling and floor effects. After correction, lateralization-performance correlations are pervasive. However, while some correlations are positive, others are negative, with the direction depending on the underlying lateralized process. Two hypotheses are proposed that can account for these relationships by pointing either to individual differences in maturation of the corpus callosum or to developmental limits encountered at different ages of childhood. Their investigation should contribute toward a neurodevelopmental theory of hemispheric asymmetry.     

The effects of head and eye turns on the right ear advantage in dichotic listening

The aim of the present experiment was to investigate the effects of head and eye turns on the ear advantage in dichotic listening (DL) to CV-syllables. Since head and eye turns also mean focusing attention to either the left or right side in space, a second aim was to evaluate recent arguments that ear advantages seen in DL are caused by the perceived position in space of the sound source. Forty right-handed females had 36 trials of CV-syllables under four different instructions. One group (n = 20) was instructed to turn their head (but not their eyes) to the right, the left, or straight ahead during stimulus presentations. The fourth condition was a standard (no instruction) condition. A second group (n = 20) had the same instructions but were told to turn their eyes instead of their heads. Conditions were pseudo-counterbalanced across subjects. Consistent with other studies, results showed a right ear advantage (REA) in both groups during all conditions. However, the REA was largest for the standard condition. Also, more subjects showed a REA during the standard condition, and especially compared to the turn-right condition. It is concluded that dichotic performance is not caused by selective attention to either side in space, and that lateral turns of the head and the eyes contralateral to the left hemisphere have an inhibitory (if anything) effect on the REA.     

Auditory orienting of attention: Effects of cues and verbal workload with children and adults

The use of tone cues has an improving effect on the auditory orienting of attention for children as for adults. Verbal cues, on the contrary, do not seem to orient attention as efficiently before the age of 9 years. However, several studies have reported inconsistent effects of orienting attention on ear asymmetries. Multiple factors are questioned, such as the role of verbal workload. Indeed, the semantic nature of the dichotic pairs and their load of processing may explain orienting of attention performance. Thus, by controlling for the role of verbal workload, the present experiment aimed to evaluate the development of capacities for the auditory orienting of attention. Right-handed, 6- to 12-year-olds and adults were recruited to complete either a tone cue or a verbal cue dichotic listening task in the identification of familiar words or nonsense words. A factorial design analysis of variance showed a significant right-ear advantage for all the participants and for all the types of stimuli. A major developmental effect was observed in which verbal cues played an important role: they allowed the 6- to 8-year-olds to improve their performance of identification in the left ear. These effects were taken as evidence of the implication of top-down processes in cognitive flexibility across development.     

Development of the deontic advantage in reasoning: Reply to Cummins

In response to Cummins’s report that comments on our article (Dack & Astington, Journal of Experimental Child Psychology, 2011, Vol. 110, pp. 94–114), this article clarifies our perspective on what constitutes the deontic advantage, and notes similarities and differences between Cummins’s perspective and our own. Like Cummins, we believe that young children are capable of deontic reasoning and that methodological factors alone cannot explain this ability. However, we maintain that it is important to be precise about methodology in order to facilitate investigation of how the deontic advantage changes over developmental time, and this question is our main interest, although as yet incompletely answered. Contrary to Cummins, we do not think that existing data can speak to the issue of the potential innateness of deontic reasoning. We also disagree with Cummins’s perspective on norm versus normative proposition and with some of her comparisons between deontic and epistemic phenomena.     

Lateralisation of language and emotion in schizotypal personality: Evidence from dichotic listening

Striking disturbances have been reported in language and emotional prosody processing by patients diagnosed with schizophrenia. In view of this and of research suggesting that schizotypal personality traits can also be expressed sub-clinically, the present study aimed to discover whether similar disturbances would be reflected in cognitive laterality patterns when symptoms of schizotypy are present yet at a non-clinical level. A dichotic listening task was used to examine the sensitivity and speed with which 132 right-handed participants (85 females and 47 males, mean age = 32.44, SD = 12.29) detected both words and emotional prosody, all of whom also completed the Schizotypal Personality Questionnaire. Findings indicated that both high (n = 64) and low (n = 68) schizotypy groups demonstrated the typical right ear advantage for the detection of words and left ear advantage for the detection of emotional prosody. Individuals with higher schizotypal personality scores also demonstrated poorer sensitivity in detecting emotional prosody. These results reveal that within the healthy population, higher levels of schizotypy are not associated with the atypical lateralisation of language and emotion. Nevertheless, the existence of these symptoms does signal the presence of shared characteristics with the clinical sphere, namely poorer emotion recognition performance.     

Hemispheric lateralization of bilaterally presented homologous visual and auditory stimuli in normal adults, normal children, and children with central auditory dysfunction

Two experiments were conducted to examine the performance of normal adults, normal children, and children diagnosed with central auditory dysfunction presumed to involve the interhemispheric pathways on a dichotic digits test in common clinical use for the diagnosis of central auditory processing disorder (CAPD) and its corresponding visual analog. Results of the first experiment revealed a significant right ear advantage (REA) for the dichotic listening task and a left-visual-field advantage (LVFA) for the corresponding visual analog in normal adults and children. In the second experiment, results revealed a significantly larger REA in the children with CAPD as compared to the normal children. Results also revealed a reversed cerebral asymmetry (RVFA) for the children with CAPD on the visual task. Significant cross-modal correlations suggest that the two tasks may reflect, at least in part, similar interhemispheric processing mechanisms in children. Findings are discussed in relation to differential diagnosis and modality-specificity of CAPD.     

Intentional attention switching in dichotic listening: Exploring the efficiency of nonspatial and spatial selection

Using an auditory variant of task switching, we examined the ability to intentionally switch attention in a dichotic-listening task. In our study, participants responded selectively to one of two simultaneously presented auditory number words (spoken by a female and a male, one for each ear) by categorizing its numerical magnitude. The mapping of gender (female vs. male) and ear (left vs. right) was unpredictable. The to-be-attended feature for gender or ear, respectively, was indicated by a visual selection cue prior to auditory stimulus onset. In Experiment 1, explicitly cued switches of the relevant feature dimension (e.g., from gender to ear) and switches of the relevant feature within a dimension (e.g., from male to female) occurred in an unpredictable manner. We found large performance costs when the relevant feature switched, but switches of the relevant feature dimension incurred only small additional costs. The feature-switch costs were larger in ear-relevant than in gender-relevant trials. In Experiment 2, we replicated these findings using a simplified design (i.e., only within-dimension switches with blocked dimensions). In Experiment 3, we examined preparation effects by manipulating the cueing interval and found a preparation benefit only when ear was cued. Together, our data suggest that the large part of attentional switch costs arises from reconfiguration at the level of relevant auditory features (e.g., left vs. right) rather than feature dimensions (ear vs. gender). Additionally, our findings suggest that ear-based target selection benefits more from preparation time (i.e., time to direct attention to one ear) than gender-based target selection.     

Left ear dichotic listening performance on consonant-vowel combinations and digits in subtypes of reading-disabled children

Twenty reading comprehension-disabled (CD) and 20 reading comprehension and word recognition-disabled (CWRD), right-handed male children were matched with 20 normal-achieving age-matched controls and 20 normal-achieving reading level-matched controls and tested for left ear report on dichotic listening tasks using digits and consonant-vowel combinations (CVs). Left ear report for CVs and digits did not correlate for any of the groups. Both reading-disabled groups showed lower left ear report on digits. On CVs the CD group showed a high left ear report but only when there were no priming precursors, such as directions to attend right first and to process digits first. Priming effects interfered with the processing of both digits and CVs. Theoretically, the CWRD group seems to be characterized by a depressed right hemisphere, whereas the CD group may have a more labile right hemisphere, perhaps tending to overengagement for CV tasks but vulnerable to situational precursors in the form of priming effects. Implications extend to (1) subtyping practices in research with the learning-disabled, (2) inferences drawn from studies using different dichotic stimuli, and (3) the neuropsychology of reading disorders.     

Cognitive abilities explaining age-related changes in time perception of short and long durations

The current study investigated how the development of cognitive abilities explains the age-related changes in temporal judgment over short and long duration ranges from 0.5 to 30 s. Children (5- and 9-year-olds) as well as adults were given a temporal bisection task with four different duration ranges: a duration range shorter than 1 s, two duration ranges longer than 3 s (4-8 s and >15 s), and an intermediate duration range (1.25-2.5 s). Their cognitive abilities were also assessed using a series of neuropsychological tests. The results showed that temporal sensitivity improved with age for each duration range but that this improvement occurred earlier for the short durations than for the long durations. Furthermore, the results revealed that the age-related improvement in time sensitivity for the durations shorter than 1 s was explained by the development of short-term memory span, whereas that for long durations was explained by the development of attention/executive functions. To summarize, the development of the abilities required to process long durations seems to be explained mainly by the development of attentional resources.     

Hemispheric asymmetry effects in children studied by dichotic listening and visual half-field testing

Dichotic listening (DL) and visual half-field (VHF) testing were used to study hemisphere asymmetry in a developmental perspective. Five-, 8-, and 11-year-old children were presented lists of fused words using a DL technique in Experiment 1, and 8- and 11-year-old children were presented pictures of common objects using a VHF technique in Experiment 2. In both experiments, measures of identification, free recall, and recognition of the words/pictures were employed. The results revealed effects of ear input (right-ear advantage) and half-field presentation (right visual half-field advantage) for all age groups, although the magnitude of this lateralization effect differed between the three memory measures. The results are discussed in relation to developmental aspects of language laterality, and in relation to the clinical utility of non-invasive lateralization techniques.     

The sad, the angry, and the asymmetrical brain: dichotic listening studies of negative affect and depression

Dichotic Listening (DL) is a valuable tool to study emotional brain lateralization. Regarding the perception of sadness and anger through affective prosody, the main finding has been a left ear advantage (LEA) for the sad but contradictory data for the anger prosody. Regarding an induced mood in the laboratory, its consequences upon DL were a diminished right ear advantage (REA) for the induction of sadness and an increased REA for the induction of anger. The global results fit with the approach-withdrawal motivational model of emotional processing, pointing to sadness as a right hemisphere emotion but anger processed bilaterally or even in the left hemisphere, depending on the subject's preferred mode of expression. On the other hand, the study of DL in clinically depressed patients found an abnormally larger REA in verbal DL tasks which was predictive of therapeutic pharmacological response. However, the mobilization of the available left hemisphere resources in these responders (reflected in a higher REA) would indicate a remission of the episode but would not assure the absence of new relapses.     

Developmental changes in face recognition during childhood: Evidence from upright and inverted faces

Adults are experts at recognizing faces but there is controversy about how this ability develops with age. We assessed 6- to 12-year-olds and adults using a digitized version of the Benton Face Recognition Test, a sensitive tool for assessing face perception abilities. Children's response times for correct responses did not decrease between ages 6 and 12, for either upright or inverted faces, but were significantly longer than those of adults for both face types. Accuracy improved between ages 6 and 12, significantly more for upright than inverted faces. Inverted face recognition improved slowly until late childhood, whereas there was a large improvement in upright face recognition between ages 6 and 8, with a further enhancement after age 12. These results provide further evidence that during childhood face processing undergoes protracted development and becomes increasingly tuned to upright faces.     

Synchrony and emotion in children and adults

This study examined both the development of synchronisation activities and the way emotion affects these activities in children and adults. Children aged from 3 to 8 years, as well as adults, performed a spontaneous motor tempo (SMT) task and a synchronisation task with a 500‐millisecond and 700‐millisecond inter‐stimulus interval (ISI), followed by a continuation task, in both an emotion‐free and an emotional context (High‐Arousal, Low‐Arousal, and Neutral). The results showed that the SMT was faster and more variable in the younger children. In addition, the younger children found it more difficult to slow down their tapping rate in synchrony with the 700‐millisecond ISI, with the result that they quickly returned to their internal tempo in the continuation phase. In contrast, the 8‐year‐olds' synchronisation performance was close to that of the adults. However, despite developmental changes in synchronisation skills, all the participants produced faster tempi in both the SMT and the synchronisation task for the High‐Arousal emotion than for the other emotions. This suggests that emotions induce an automatic distortion of motor timing as has also been observed for the perception of time.     

A sound effect: Exploration of the distinctiveness advantage in voice recognition

Two experiments are presented, which explore the presence of a distinctiveness advantage when recognising unfamiliar voices. In Experiment 1, distinctive voices were recognised significantly better, and with greater confidence, in a sequential same/different matching task compared with typical voices. These effects were replicated and extended in Experiment 2, as distinctive voices were recognised better even under challenging listening conditions imposed by nonsense sentences and temporal reversal. Taken together, the results aligned well with similar results when processing faces, and provided a useful point of comparison between voice and face processing.