Perceptual processing in dichotic listening.

Subjects heard two lists of 4 items each presented simultaneously to the two ears at a rate of four pairs of items per sec. A recall cue presented immediately after the test list signalled report of 4 of the 8 items. In recall by spatial location, the cue indicated whether the items on the right ear on left ear should be recalled. In recall by category name, the cue indicated the superset category (e.g., letters or words) of the items to be recalled. Recall by spatial location was not significantly different than recall by category name. This results argues against the idea of a preperceptual auditory storage that holds information along spatial channels for 1 or 2 sec. The final experiment showed that recall by spatial location is significantly better than recall by category name when the report cue is given before, not after, the list presentation. These results show that spatial location can be used to enhance semantic processing and/or memory of 1 of 2 simultaneous items, but only if the relevant location is known at the time of the item presentation.     

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.     

A forced-attention dichotic listening fMRI study on 113 subjects

We report fMRI and behavioral data from 113 subjects on attention and cognitive control using a variant of the classic dichotic listening paradigm with pairwise presentations of consonant-vowel syllables. The syllable stimuli were presented in a block-design while subjects were in the MR scanner. The subjects were instructed to pay attention to and report either the left or right ear stimulus. The hypothesis was that paying attention to the left ear stimulus (FL condition) induces a cognitive conflict, requiring cognitive control processes, not seen when paying attention to the right ear stimulus (FR condition), due to the perceptual salience of the right ear stimulus in a dichotic situation. The FL condition resulted in distinct activations in the left inferior prefrontal gyrus and caudate nucleus, while the right inferior frontal gyrus and caudate were activated in both the FL and FR conditions, and in a non-instructed (NF) baseline condition.     

Preattentive control of serial auditory processing in dichotic listening

Dichotic listening performance was examined in an auditory selective attention task where subjects responded to occasional consonant-vowel (CV) or shaped broadband noise-burst (NB) targets in rapid serial auditory presentation (RASP). Trial types were randomized and included monaural CVs and NBs as well as dichotic CV-CV and CV-NB pairings. CVs were spoken by two different voices (male and female), and the two NB stimuli differed in their filter slopes at higher frequencies. The target was designated by stimulus category (/ba/, /da/, /ga/, or NB) and voice (e.g., "female /ba/"). Performance was compared for targets in the left and right ears on monaural and dichotic trials using accuracy and reaction time (RT) measures. Right ear advantages (REAs) were present for CV targets with either CV or NB distractors, but not for monaural CVs. The REA found for monaural NB targets was eliminated by CV distractors, yielding a left ear advantage (LEA) for the distractor effect of CVs on NB targets. The pattern of results suggests initial preprocessing of speech stimuli through phonetic feature analysis, followed by serial attentional processing of the objects in the auditory field. REAs are attributed to a rightward asymmetry in the preattentive control of auditory attention similar to that found in visual search.     

The effect of thalamic stimulation in processing of verbal stimuli in dichotic listening tasks: a case study

In dichotic listening tasks, the (dominant) right ear's superiority in processing verbal stimuli has been attributed to its direct anatomic connection with the left dominant hemisphere. The role played by extralinguistic factors, such as attention and functional tuning of the associated cortical structures, has not been carefully examined. This investigation was undertaken to evaluate the effects of the left thalamic electric stimulation on the processing (recognition and recall) of dichotically presented CVC verbal stimuli in a patient being treated for chronic pain. We report the positive effects of electric stimulation (confirmed by increased subcortical metabolic activity using SPECT, a brain imaging technique) on the processing of dichotically presented verbal stimuli.     

A dichotic listening study of attention control in older adults

The influence of age on attentional control of bottom-up processing was investigated with a dichotic-listening paradigm. The typical right-ear-advantage (REA) without specific attentional instructions was used as a measure of bottom-up processing (non-forced condition). Top-down attentional control was evaluated by instructing subjects to report only the right or left ear stimulus of the dichotic pair (forced-right, forced-left conditions). Both young and old participants showed a REA in the non-forced condition and an increased REA in the forced-right condition. The old group failed, however, to use attention to modulate the REA to the same degree as the younger participants in the forced-left condition. Only the young group showed a significant left ear advantage (LEA). The results are discussed in relation to cognitive decline in normal aging and in early stages of dementia.     

The syntagmatic-paradigmatic shift in dichotic listening

Children at two age levels, 6 to 7 years and 9 to 10 years, listened to pairs of words presented dichotically to the left and right ear either simultaneously or in immediate succession. Their task was to report what they heard after each pair. The experimental pairs involved either syntagmatic relations (e.g., bird-fly) or paradigmatic relations (table-chair). The younger children correctly identified more syntagmatic than paradigmatic pairs (using control pairs as a base) while the older children correctly identified more paradigmatic pairs. There was no difference between associated and nonassociated pairs. The results are taken to mean that pragmatic, serial relations dominate the semantic organization of younger children and that logical, hierarchical relations make their impact later in the course of development.     

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.     

The development of handedness and dichotic ear listening asymmetries in relation to school achievement: A longitudinal study

To assess the development of dichotic ear asymmetries and handedness, 208 male school children were evaluated in kindergarten and at Grades 2 and 5 (ages 66, 92, and 130 months of age, respectively) with a dichotic listening task and a hand preference test. The Wide Range Achievement Test (WRAT) also was administered at each of the three grade levels. There was significant variability in handedness scores over time only for those subjects whose scores at initial testing, that is, in kindergarten, identified them as non-right-handers. Both right and left handers had a significant increase in dichotic listening scores over time; however, only right handers had a significant right ear advantage at each evaluation. Regression analyses showed that combined hand preference scores and ear recall scores at each probe when combined accounted for almost 44% of the variance in WRAT achievement scores at Grade 5. Ear asymmetry scores, however, were not predictive of school achievement.     

Dependent processing in dichotic listening as a function of word meaning attributes

Single dichotic word pairs were presented for immediate identification. Recognition probability was greater and response latencies shorter for high- than for low-frequency words. Both recognition measures were also affected by the frequency of the word accompanying the target word, performance being facilitated by a high-frequency partner and sometimes impaired by a low-frequency partner. Associative meaningfulness had similar, though less reliable, effects whereas the effects of word concreteness-abstractness were inconsistent. Recognition accuracy was generally superior for right-ear inputs, but recognition latency did not show consistent ear effects. Similar results were obtained under both unrestricted (Experiment 1) and controlled (Experiment 2) ear order of report instructions. The findings are consistent with a limited capacity interpretation of secondary processing in word perception.     

Hormones and dichotic listening: evidence from the study of menstrual cycle effects

This report presents evidence for changes in dichotic listening asymmetries across the menstrual cycle, which replicate studies from our laboratory and others. Increases in the right ear advantage (REA) were present in women at phases of the menstrual cycle associated with higher levels of ovarian hormones. The data also revealed correlations between hormone levels and behavioural measures of asymmetry. For example, the pre-ovulatory surge in luteinising hormone (LH) was related to a decrease in left ear scores, which comprised a key part of the cycle related shift in asymmetry. Further analysis revealed a subgroup of women who had not reached postovulatory status by days 18-25 of the cycle, as verified by low progesterone levels. These women showed laterality profiles at days 18-25 that looked more like the other women when measured at the periovulatory phase (i.e., days 8-11). Data were combined with those from a previous study to highlight the stability of effects. Results showed a distinct menstrual cycle related increase in asymmetry in the combined sample. This final comparison confirmed the nature of sex differences in dichotic listening as being dependent on hormone status in women.     

Memory and personality: An information processing approach

A consensual model of memory, based on information processing theory is presented. The experimental literature on the interaction between memory and personality is reviewed in terms of this model. It is suggested that past study in this area has failed to utilize the knowledge and techniques of information processing theory, and as a result, has confounded experimental variables. Suggestions for more appropriate research are presented.     

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.     

Differentiating avoidant and depressive personality disorders

The purpose of this study was to test a priori predictions about the way in which avoidant personality disorder (APD) can be differentiated from depressive personality disorder (DPD) in a clinical population. Psychiatric outpatients were administered two measures of DPD, including the SCID-II for other DSM-IV Axis II personality disorders, along with criterion measures upon which the two disorders would be differentiated. APD was found to be most strongly associated with state and trait measures of anxiety, while DPD was most strongly associated with state and trait measures of hostility. Individuals with DPD had higher mean scores on measures of hostility than those without DPD, and individuals with APD had higher mean scores on measures of anxiety than those without APD. However, DPD measures were also significantly correlated with state and trait measures of anxiety and APD with measures of depressive symptoms. Furthermore, anxiety was found to be higher in some groups of individuals with DPD than those with APD. It is concluded that the level of hostility in this DPD population appears to be an important symptom by which to differentiate the two disorders and that a reconsideration of including DPD criterion #4 -- prone to brooding and worrying -- may be justified. Furthermore, the SCID-II interview may be better at differentiating DPD and APD than a self-report measure of DPD.     

Selective attention to emotional prosody in social anxiety: a dichotic listening study

The majority of evidence on social anxiety (SA)-linked attentional biases to threat comes from research using facial expressions. Emotions are, however, communicated through other channels, such as voice. Despite its importance in the interpretation of social cues, emotional prosody processing in SA has been barely explored. This study investigated whether SA is associated with enhanced processing of task-irrelevant angry prosody. Fifty-three participants with high and low SA performed a dichotic listening task in which pairs of male/female voices were presented, one to each ear, with either the same or different prosody (neutral or angry). Participants were instructed to focus on either the left or right ear and to identify the speaker’s gender in the attended side. Our main results show that, once attended, task-irrelevant angry prosody elicits greater interference than does neutral prosody. Surprisingly, high socially anxious participants were less prone to distraction from attended-angry (compared to attended-neutral) prosody than were low socially anxious individuals. These findings emphasise the importance of examining SA-related biases across modalities.     

Emotional dysfunction in avoidant compared to borderline personality disorder: A study of affect consciousness

Knowledge of emotional dysfunction in patients with avoidant personality disorder (APD) is much needed. The present study examined affect consciousness (AC) in patients with APD compared to borderline personality disorder (BPD). AC, defined as capacity to perceive, reflect on, tolerate, and express emotional experiences, is assumed to be central to structure‐building in personality. The study tested the hypotheses that patients with APD have lower general AC and lower AC for pleasant affects compared to BPD. Fifty‐nine patients, 26 with APD and 33 with BPD were rated on several aspects of AC using the specialized AC interview. The structured interview SCID‐II was applied for diagnostic evaluations. The APD group had significantly lower levels of global AC and conceptual expressivity compared to the BPD group. Among 11 specific affects the APD group had significantly lower AC for interest and contempt. Emotional dysfunction is an important feature of APD and the findings indicate that psychotherapies for APD patients should focus on emotional experiences, aiming to improve emotional awareness, tolerance, and expressivity. The notion of a general avoidance of positive emotions in APD needs further exploration, including a possible dysfunction in the evolutionary based neuro‐affective Seeking system.