Josef J. Bless

“Right on all Occasions?” – On the Feasibility of Laterality Research Using a Smartphone Dichotic Listening Application

Most psychological experimentation takes place in laboratories aiming to maximize experimental control; however, this creates artificial environments that are not representative of real-life situations. Since cognitive processes usually take place in noisy environments, they should also be tested in these contexts. The recent advent of smartphone technology provides an ideal medium for such testing. In order to examine the feasibility of mobile devices (MD) in psychological research in general, and laterality research in particular, we developed a MD version of the widely used speech laterality test, the consonant-vowel dichotic listening (DL) paradigm, for use with iPhones/iPods. First, we evaluated the retest reliability and concurrent validity of the DL paradigm in its MD version in two samples tested in controlled, laboratory settings (Experiment 1). Second, we explored its ecological validity by collecting data from the general population by means of a free release of the MD version (iDichotic) to the iTunes App Store (Experiment 2). The results of Experiment 1 indicated high reliability (rICC = 0.78) and validity (rICC = 0.76–0.82) of the MD version, which consistently showed the expected right ear advantage (REA). When tested in real-life settings (Experiment 2), participants (N = 167) also showed a significant REA. Importantly, the size of the REA was not dependent on whether the participants chose to listen to the syllables in their native language or not. Together, these results establish the current MD version as a valid and reliable method for administering the DL paradigm both in experimentally controlled as well as uncontrolled settings. Furthermore, the present findings support the feasibility of using smartphones in conducting large-scale field experiments.

Laterality across languages: Results from a global dichotic listening study using a smartphone application.

Left-hemispheric language dominance has been suggested by observations in patients with brain damages as early as the 19th century, and has since been confirmed by modern behavioural and brain imaging techniques. Nevertheless, most of these studies have been conducted in small samples with predominantly Anglo-American background, thus limiting generalization and possible differences between cultural and linguistic backgrounds may be obscured. To overcome this limitation, we conducted a global dichotic listening experiment using a smartphone application for remote data collection. The results from over 4,000 participants with more than 60 different language backgrounds showed that left-hemispheric language dominance is indeed a general phenomenon. However, the degree of lateralization appears to be modulated by linguistic background. These results suggest that more emphasis should be placed on cultural/linguistic specificities of psychological phenomena and on the need to collect more diverse samples.

The role of the primary auditory cortex in the neural mechanism of auditory verbal hallucinations

Auditory verbal hallucinations (AVHs) are a subjective experience of “hearing voices” in the absence of corresponding physical stimulation in the environment. The most remarkable feature of AVHs is their perceptual quality, that is, the experience is subjectively often as vivid as hearing an actual voice, as opposed to mental imagery or auditory memories. This has lead to propositions that dysregulation of the primary auditory cortex (PAC) is a crucial component of the neural mechanism of AVHs. One possible mechanism by which the PAC could give rise to the experience of hallucinations is aberrant patterns of neuronal activity whereby the PAC is overly sensitive to activation arising from internal processing, while being less responsive to external stimulation. In this paper, we review recent research relevant to the role of the PAC in the generation of AVHs. We present new data from a functional magnetic resonance imaging (fMRI) study, examining the responsivity of the left and right PAC to parametrical modulation of the intensity of auditory verbal stimulation, and corresponding attentional top-down control in non-clinical participants with AVHs, and non-clinical participants with no AVHs. Non-clinical hallucinators showed reduced activation to speech sounds but intact attentional modulation in the right PAC. Additionally, we present data from a group of schizophrenia patients with AVHs, who do not show attentional modulation of left or right PAC. The context-appropriate modulation of the PAC may be a protective factor in non-clinical hallucinations.

Cognitive Control of Speech Perception across the Lifespan: A Large-Scale Cross-Sectional Dichotic Listening Study.

The ability to use cognitive-control functions to regulate speech perception is thought to be crucial in mastering developmental challenges, such as language acquisition during childhood or compensation for sensory decline in older age, enabling interpersonal communication and meaningful social interactions throughout the entire life span. Although previous studies indicate that cognitive control of speech perception is subject to developmental changes, its exact developmental trajectory has not been described. Thus, examining a sample of 2,988 participants (1,119 women) with an age range from 5 to 89 years, the aim of the present cross-sectional study was to examine the development of cognitive control of speech perception across the life span using age as continuous predictor. Based on data collected with the forced-attention consonant-vowel dichotic listening paradigm, the data analysis revealed an inverted U-shaped association of age and performance level: A steep increase in performance level was seen throughout childhood and adolescence, reaching highest performance in the early 20s, and was followed by a monotonous, continuous decline into late adulthood. Thus, cognitive control of speech perceptions shows similar life span developmental trajectories as observed regarding cognitive-control functions in other domains, for example, as assessed in the visual domain.

Cognitive control deficits in adolescents born with very low birth weight (≤ 1500 g): Evidence from dichotic listening

The objective of the paper is to explore bottom-up auditory and top-down cognitive processing abilities as part of long-term outcome assessment of preterm birth. Fifty-five adolescents (age 13-15) born with very low birth weight (VLBW) were compared to 80 matched controls born to term, using three consonant-vowel dichotic listening (DL) instruction conditions (non-forced, forced-right and forced-left). DL scores were correlated with cortical gray matter thickness derived from T1-weighted structural MRI volumes using FreeSurfer to examine group differences also in the neural correlates of higher cognitive processes. While showing normal bottom-up processing, VLBW adolescents displayed impaired top-down controlled conflict processing related to significant cortical thickness differences in left superior temporal gryus and anterior cingulate cortex. Preterm birth with VLBW induces fundamental changes in brain function and structure posing a risk for long-term neurocognitive impairments. Deficits emerge in situations of increasing cognitive conflict and can be related to measures of executive functions as well as morphology.

Behavioral Laterality and Aging: The Free-Recall Dichotic-Listening Right-Ear Advantage Increases With Age

The effect of aging on brain asymmetry was studied under consideration of possible confounding effects of known age-related decline in higher cognitive functioning. In a sample of 3,680 participants aged 20–79 years, laterality was assessed with a verbal, free-recall dichotic-listening paradigm with one stimulus pair presentation per trial, minimizing working-memory and cognitive-control demands during task performance. Laterality, reflected as right-ear preference for dichotic stimuli, was found to be increased in older age (above 60 years). This effect was due to a reduced report of left-ear stimuli, while the report of right-ear stimuli stayed on comparable levels across all ages.

Investigating heritability of laterality and cognitive control in speech perception

Several studies analyzing the ontogenetic origin of cerebral lateralization provide evidences for a genetic foundation of handedness in humans that is modulated by environmental influences. Since other forms of behavioral lateralization are less investigated, it is unclear as to how far different functions display similar heritability. But deeper knowledge is necessary to understand if and how developmental coupling of different functions is based on a shared genetic background or on the impact of environmental influences. Here, we investigated the heritability of language lateralization assessed with the dichotic listening task, as well as the heritability of cognitive control processes modulating performance in this task. Overall, 103 families consisting of both parents and offspring were tested with the non-forced, as well as the forced-right and forced-left condition of the forced attention dichotic listening task, implemented in the iDichotic smartphone app, developed at the University of Bergen, Norway. The results indicate that the typical right ear advantage in the dichotic listening task shows weak and non-significant heritability (h2=0.003; p=0.98). In contrast, cognitive factors, like attention focus (forced right condition: h2=0.36; p<0.01; forced left condition: h2=0.28; p<0.05) and cognitive control (Gain forced right: h2=0.39; p<0.01; Gain forced left: h2=0.49; p<0.01) showed stronger and significant heritability. These findings indicate a variable dependence of different aspects of a cognitive function on heritability and implicate a major contribution of non-genetic influences to individual language lateralization.

Cognitive Control Processes and Functional Cerebral Asymmetries: Association with Variation in the Handedness-Associated Gene LRRTM1

Cognitive control processes play an essential role not only in controlling actions but also in guiding attentional selection processes. Interestingly, these processes are strongly affected by organizational principles of the cerebral cortex and related functional asymmetries, but the neurobiological foundations are elusive. We ask whether neurobiological mechanisms that affect functional cerebral asymmetries will also modulate effects of top-down control processes on functional cerebral asymmetries. To this end, we examined potential effects of the imprinted gene leucine-rich repeat transmembrane neuronal 1 (LRRTM1) on attentional biasing processes in a forced attention dichotic listening task in 983 healthy adult participants of Caucasian descent using the “iDichotic smartphone app.” The results show that functional cerebral asymmetries in the language domain are associated with the rs6733871 LRRTM1 polymorphism when cognitive control and top-down attentional mechanisms modulate processes in bottom-up attentional selection processes that are dependent on functional cerebral asymmetries. There is no evidence for an effect of LRRTM1 on functional cerebral asymmetries in the language domain unrelated to cognitive control processes. The results suggest that cognitive control processes are an important factor to consider when being interested in the molecular genetic basis of functional cerebral architecture.

Training switching focus with a mobile-application by a patient suffering from AVH, a case report

Auditory verbal hallucinations complicate many psychiatric disorders. Antipsychotic medication is effective in the majority, but a significant minority experiences high burden from resistant hallucinations. Here, we aim to improve executive control, in an attempt to decrease burden from hallucinations. We describe the use of a cognitive trainings app by a young woman with highly resistant hallucinations. With modest training, a significant decrease in the duration of hallucinations was reached. Possibilities of this training technique are discussed.

The Beliefs about Voices Questionnaire – Revised: A factor structure from 450 participants

Hallucinated voices are common across psychiatric and non-clinical groups. The predominant cognitive theory about the impact of voices posits that beliefs about voice power (‘Omnipotence’) and voice intent (‘Malevolence’/‘Benevolence’) play a key role in determining emotional and behavioral reactions. The revised Beliefs about Voices Questionnaire (BAVQ-R) was designed to assess these constructs, together with two styles of responding (Engagement and Resistance). The BAVQ-R is widely used in clinical and research settings, yet it has not received validation of its constructs and factor structure. This study examined the factor structure of the BAVQ-R by combining datasets from five study centers, comprising 450 participants (belief constructs) and 269 participants (response styles), and using confirmatory and exploratory factor analysis. Findings failed to support a three factor belief model, instead showing a two-factor structure (‘Persecutory beliefs’ combining Omnipotence and Malevolence constructs, and a Benevolent construct). Emotional and behavioral items did not separate. Overall, results showed that (i) a two-factor model of beliefs (Persecutory and Benevolent beliefs) provides a better fit to the data than a three-factor model, and (ii) emotional and behavioral modes of responding items should not be separated. Theoretical implications of this finding are discussed in relation to the research and therapy.