Adaptation and Serial Dependence in the Perception of Line Orientation in Autism Spectrum Disorder

Although the emphasis in the description and diagnosis of Autism Spectrum
Disorder often lies with the social and behavioral characteristics of the
disorder, autism is also characterised by atypical perception. It has even been
suggested that the atypical perception could partly explain the other symptoms
of autism.

Sensory information, such as visual input, is noisy. A lot of input is
ambiguous and can be interpreted in many different ways. In normal perception,
the brain resolves this ambiguity by means of 'priors' - an internal model of
the world that is constantly calibrated by experience and expectation. Through
priors the brain finds the best interpretation for ambiguous input.

According to a recent hypothesis, the perceptual atypicalities may be caused by
"hypo-priors"; the internal model used to process sensory information, such as
visual input, is too broad. Because of hypo-priors, the integration of the
model and visual information is less successful. Ambiguous input is therefore
more difficult to interpret. This could explain why many people with autism
indicate they experience the world as stressful, and why many of them prefer
routine.

Adaptation is closely connected to priors: input recalibrates the prior, which
has an influence on how the input that follows is interpreted. If there are
indeed hypo-priors in autism, the prior should be refined less adequately.
Consequently, there should be less adaptation. By measuring adaptation, we can
therefore say something about the priors.

A number of published studies indeed find less adaptation in autism. However,
others studies do not find this effect. Based on the findings it has been
suggested that low-level adaptation is intact while high-level perceptual
effects are affected in autism.

In this study we use a unique paradigm which can be used to examine both
high-level (serial dependence) effects as low-level (adaptation) effects. By
doing so we hope to resolve the discrepancy in the previous findings.

We expect that low-level adaptation is intact in autism, while on a high level
of processing there are differences between individuals with and without
autism, specifically that in autism there is less integration of current and
previous input.

The results of this study may bring clarity about hypo-priors in autism, and
therefore possibly about the nature of atypical perception in autism. This
could lead to the development of interventions and therapies that target
sensory processing in children and adolescents in autism. If the atypical
perception indeed contributes to the other symptoms in autism, these therapies
could affect these symptoms as well.

This observational study uses a cross-sectional design in which two groups are
compared to each other.

The burden that comes with this study is relatively low. Participants will come
to the Donders Insitute for an appointment that lasts a few hours
(approximately 3 hours). During this appointment they will do a few tasks of
the WISC or WAIS IQ tests and will do a computer task on the computer. Both
last approximately an hour and are doable for the study population.

If the participant has autism, an Autism Diagnostic Interview is conducted with
their parent. This interview takes 1 to 1.5 hours. The interview does not
require the participation of the adolescent themselves.

Participants will fill in 2 questionnaires (max 30 minutes total). Their
parents will fill in 3 or 4 questionnaires (approx. 1-2 hours). The
questionnaires are standardised questionnaires that are used in scientific
research. These questionnaires participants and their parents may fill in at
home, when it suits them (but before a set deadline). This will allow
participants more freedom.

The risk of this study is negligible. There is no intervention, and no medical
substances or apparatuses are used. None of the procedures come with any risk.

This study uses underage participants, because the sensory characteristics of
Autism Spectrum Disorder are especially prominent during development. It are
these characteristics that we want to investigate, which is why it is necessary
to approach adolescents for this study. Although these adolescents do not
directly benefit from participation, the knowledge acquired with this study
could be used to develop neuropsychological treatments that would be
specifically helpful for this population, who are still in development. Adults
are a less suited study population, as 1) the sensory characteristics of autism
are likely less or not present in this population and 2) treatment methods that
could be developed would likely have less effect on a post-development
population.