Visual integration of direction and orientation information in autistic children

Abstract

Background and aims: The vision of autistic people has been characterised as focused on detail, with a disinclination (or reduced ability) to integrate information into coherent 'wholes'. In contrast to this view, we recently demonstrated enhanced integration of visual motion signals in autistic children compared to typically developing children. Here, we aimed to investigate the robustness of our finding of increased motion integration in autism with a new sample of children and to determine whether increased integration in autistic children would extend to a static, orientation judgement. Methods: We presented motion and orientation equivalent noise and coherence tasks to 46 autistic children aged 6 to 14 years and 45 typically developing children matched in age and non-verbal IQ. The equivalent noise tasks consisted of two interleaved conditions: a high-noise condition in which children judged the average direction or orientation of elements whose range of direction or orientations was manipulated, and a no-noise condition in which children judged the direction or orientation of elements sharing the same direction or orientation. Equivalent noise modelling provided estimates of internal noise (the precision with which children can estimate the orientation/direction of one element) and global sampling (how many elements children are effectively using to judge the overall orientation/direction). Children also completed coherence tasks in which the proportion of signal elements sharing the same direction or orientation amidst otherwise random noise elements was manipulated. We assessed group differences using a combination of frequentist and Bayesian statistical approaches. Results: Analysis of the data in this new sample alone did not provide sufficient evidence either in favour or against the hypothesis of increased integration in autism. However, when combining motion data from this and the original experiment, autistic children exhibited superior integration of direction information in the high-noise condition compared to typically developing children, with similar no-noise and coherence thresholds. Equivalent noise modelling of these data revealed increased sampling in autistic children for motion information but no conclusive evidence for atypical levels of internal noise. There was no evidence of differences between autistic and typically developing children in the orientation equivalent noise and coherence tasks. Conclusions: Overall, autistic children effectively integrated more direction information than typically developing children. However, the groups overlapped considerably and there was substantial individual variability, so that the effect may be difficult to detect in small groups. There was no indication of atypical integration of orientation in the current study, although larger samples will be required in order to provide conclusive evidence. Implications: These results help characterise the nature of sensory processing in autism, which is of high import and relevance given the recent inclusio...

Internal noise measures in coarse and fine motion direction discrimination tasks, and the correlation with autism traits

“…Lower multiplicative noise would yield better performance at high external noise levels but not at low external noise levels (see e.g. Figure 1B), consistent with previous findings (Manning et al, 2015;Manning et al, 2017). Therefore, we suggest that the cause for the increased performance in ASD on the motion task is due to decreased multiplicative noise (or increased noise exclusion), and not due to increased motion pooling.…”

“…Similar differences in neural variability were found using resting state measurements in magnetoencephalography (MEG; Domínguez et al, 2013), suggesting that high internal noise is a widespread cortical characteristic of ASD and may represent a fundamental physiological alteration of neural processing (but see, Butler, Molholm, Andrade, & Foxe, 2017;Coskun et al, 2009). At a behavioural level, the impact of internal noise on visual perception in ASD has mostly been investigated in the motion and orientation domain (Manning, Tibber, Charman, Dakin, & Pellicano, 2015;Manning, Tibber, & Dakin, 2017;Park, Schauder, Zhang, Bennetto, & Tadin, 2017;Zaidel, Goin-Kochel, & Angelaki, 2015).…”

“…We found no significant correlation between motion pooling across AQ score, and Bayesian statistics suggested that there was moderate evidence for the absence of a correlation in the fine motion discrimination task, while the data was inconclusive in the coarse discrimination task. As mentioned above, the increased motion pooling in ASD, reported in previous studies (Manning et al, 2015;Manning et al, 2017), is instead potentially attributable to decreased multiplicative noise (or increased noise exclusion).…”

High internal noise and poor external noise filtering characterize perception in autism spectrum disorder

“…We do not yet have a good understanding of causes and computational principles that might underlie increased neural variability in ASD 21 , and several theoretical accounts suggest an opposite possibility that internal noise may be reduced in ASD 22 , 23 . Notably, a number of studies challenge the noisy brain hypothesis in ASD by demonstrating typical levels of variability in evoked EEG 24 and MEG 25 responses to sensory stimulation, as well as in psychophysically estimated internal noise 26 , 27 . At the core of this controversy lies the issue of whether a domain-general account of ASD, such as the ones involving elevated internal noise and neural variability, can truly explain the complex phenotypes in individual with ASD 24 .…”

“…The benefits of using equivalent noise paradigms to investigate internal noise in ASD have been previously highlighted 12 , 14 . In fact, two studies used a reduced version of this paradigm and found no significant evidence for elevated internal noise in ASD 26 , 27 . However, two important unanswered questions remain.…”