Asymmetries in attention as revealed by fixations and saccades

Loetscher, Tobias; Nicholls, Michael E. R.

doi:10.1007/s00221-014-4015-9

Cited by 14 publications

(9 citation statements)

References 78 publications

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“…When training was provided with spatiotemporally congruent visual and auditory cues, we found the biases tended to correct to a point just to the left of the midline rather than at the midline itself. This may find an explanation in recent studies of pseudoneglect that demonstrate opposite spatial attentional biases for visual and auditory stimuli in healthy listeners, such that performance in spatial attention tasks is characterized by a leftward bias for visual stimuli (Loftus and Nicholls, 2012; Thomas et al, 2014, 2017) and a rightward bias for stimuli presented to the auditory modality (Sosa et al, 2010, 2011). These biases have been postulated to result from hemispheric asymmetries in controlling the deployment of spatial attention.…”

Section: Discussionmentioning

confidence: 91%

Re-weighting of Sound Localization Cues by Audiovisual Training

et al. 2019

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Sound localization requires the integration in the brain of auditory spatial cues generated by interactions with the external ears, head and body. Perceptual learning studies have shown that the relative weighting of these cues can change in a context-dependent fashion if their relative reliability is altered. One factor that may influence this process is vision, which tends to dominate localization judgments when both modalities are present and induces a recalibration of auditory space if they become misaligned. It is not known, however, whether vision can alter the weighting of individual auditory localization cues. Using virtual acoustic space stimuli, we measured changes in subjects’ sound localization biases and binaural localization cue weights after ∼50 min of training on audiovisual tasks in which visual stimuli were either informative or not about the location of broadband sounds. Four different spatial configurations were used in which we varied the relative reliability of the binaural cues: interaural time differences (ITDs) and frequency-dependent interaural level differences (ILDs). In most subjects and experiments, ILDs were weighted more highly than ITDs before training. When visual cues were spatially uninformative, some subjects showed a reduction in auditory localization bias and the relative weighting of ILDs increased after training with congruent binaural cues. ILDs were also upweighted if they were paired with spatially-congruent visual cues, and the largest group-level improvements in sound localization accuracy occurred when both binaural cues were matched to visual stimuli. These data suggest that binaural cue reweighting reflects baseline differences in the relative weights of ILDs and ITDs, but is also shaped by the availability of congruent visual stimuli. Training subjects with consistently misaligned binaural and visual cues produced the ventriloquism aftereffect, i.e., a corresponding shift in auditory localization bias, without affecting the inter-subject variability in sound localization judgments or their binaural cue weights. Our results show that the relative weighting of different auditory localization cues can be changed by training in ways that depend on their reliability as well as the availability of visual spatial information, with the largest improvements in sound localization likely to result from training with fully congruent audiovisual information.

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Section: Discussionmentioning

confidence: 91%

Re-weighting of Sound Localization Cues by Audiovisual Training

et al. 2019

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“…Exposure to spatially-congruent auditory and visual stimuli (AVCON) produced the largest corrective bias reductions in subjects with larger initial localization biases (Figure 9A), although there was some indication that they corrected to a point just to the left of the midline rather than at the midline itself. This may find an explanation in recent studies of pseudoneglect that demonstrate opposite spatial attentional biases for visual and auditory stimuli in healthy listeners, such that performance in spatial attention tasks is characterized by a leftward bias for visual stimuli (Loftus and Nicholls, 2012; Thomas et al, 2014, 2017) and a rightward bias for stimuli presented to the auditory modality (Sosa et al, 2010, 2011). These biases have been postulated to result from hemispheric asymmetries in controlling the deployment of spatial attention.…”

Section: Discussionmentioning

confidence: 91%

Re-weighting of Sound Localization Cues by Audiovisual Training

Kumpik

Campbell

Schnupp

et al. 2019

Preprint

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The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest Author contribution statement DK, JS and AK conceived and designed the study; DK and CC carried out the experiments and analyzed the data; DK, JS and AK wrote the manuscript. Abstract Word count: 350Sound localization requires the integration in the brain of auditory spatial cues generated by interactions with the external ears, head and body. Perceptual learning studies have shown that the relative weighting of these cues can change in a contextdependent fashion if their relative reliability is altered. One factor that may influence this process is vision, which tends to dominate localization judgments when both modalities are present and induces a recalibration of auditory space if they become misaligned. It is not known, however, whether vision can alter the weighting of individual auditory localization cues. Using non-individualized head-related transfer functions, we measured changes in subjects' sound localization biases and binaural localization cue weights after ~55 minutes of training on an audiovisual spatial oddball task. Four different configurations of spatial congruence between visual and auditory cues (interaural time differences (ITDs) and frequency-dependent interaural level differences (interaural level spectra, ILS) were used. When visual cues were spatially congruent with both auditory spatial cues, we observed an improvement in sound localization, as shown by a reduction in the variance of subjects' localization biases, which was accompanied by an up-weighting of the more salient ILS cue. However, if the position of either one of the auditory cues was randomized during training, no overall improvement in sound localization occurred. Nevertheless, the spatial gain of whichever cue was matched with vision increased, with different effects observed on the gain for the randomized cue depending on whether ITDs or ILS were matched with vision. As a result, we observed a similar up-weighting in ILS when this cue alone was matched with vision, but no overall change in binaural cue weighting when ITDs corresponded to the visual cues and ILS were randomized. Consistently misaligning both cues with vision produced the ventriloquism aftereffect, i.e., a corresponding shift in auditory localization bias, without affecting the variability of the subjects' sound localization judgments, and no overall change in binaural cue weighting. These data show that visual contextual information can invoke a reweighting of auditory localization cues, although concomitant improvements in sound localization are only likely to accompany training with fully congruent audiovisual information. Contribution to the fieldFor the brain to construct a single unified percept of the world, it is necessary that information from our different senses is combined and integrated. This is often thought to be achieved in a statistically optimal fashion with different se...

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“…Visuospatial tasks are perceptual, however, the strategies used to complete visuospatial tasks influence orientation of attention across the visual field (Thomas et al 2014 ). Pesudoneglect is often explained by the preferential activation of the right hemisphere that distributes attention to the left visual field and increases the salience of features located in the left hemispace—the activation-orienting hypothesis (Kinsbourne 1970 ).…”

Section: Discussionmentioning

confidence: 99%

Behavioural asymmetries on the greyscales task: The influence of native reading direction

Friedrich

Elias

2014

Cult. Brain

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Reliable leftward attentional and perceptual biases demonstrated in a variety of visuospatial tasks have been found to deviate from the left in research examining the influence of scanning habits. The aim of the current research was to examine the influence of native script direction on pseudoneglect during the greyscales task in a representative sample of native right-to-left readers. Fifty-four native left-to-right readers and 43 right-to-left readers completed the greyscales task, which required judging the darker of two left–right mirrored brightness gradients. Native left-to-right readers demonstrated a left response bias on the greyscales task, whereas right-to-left readers failed to demonstrate a bias, however, both groups responded more quickly when making leftward choices. The research suggests that the strength of attentional biases are influenced by behavioural biases, such as scanning habits, and neural and anatomical asymmetries in the right parietal and frontal cortices. Thus, to improve the clinical utility of the greyscales task for diagnosing neglect, right-to-left readers should be examined to fully understand the normal range of biases displayed by neurologically healthy individuals.

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Asymmetries in attention as revealed by fixations and saccades

Cited by 14 publications

References 78 publications

Re-weighting of Sound Localization Cues by Audiovisual Training

Re-weighting of Sound Localization Cues by Audiovisual Training

Re-weighting of Sound Localization Cues by Audiovisual Training

Behavioural asymmetries on the greyscales task: The influence of native reading direction

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