Multisensory and temporal processing in adolescents with Autism Spectrum Disorders; a comparative study between healthy and autistic adolescents

The perception of the world around us largely determines how we attend to and
behave in the world. To correctly respond to the situations around us, it is
important to have the right information about the situation. The development of
normal perception is rooted on basic abilities like the capacity to integrate
information from multiple sources of information. Multisensory integration
entails that information from different modalities which is combined into a
coherent percept. If this integration is disrupted, it could lead to deviant
behavior in communication and social interaction, which are main
characteristics of autism. Many theories about autism postulate that sensory
abnormalities are core symptoms of autism with downstream effects on the
development of the perceptual system. We would like to study whether
multisensory processing of autistics differs from healthy persons. In this
study we specifically focus on temporel processing, because limited, recent
studies postulate that autistics have temporal problems in (multi)sensory
processing.

The primary objective is to investigate how autistic adolescents integrate
multisensory information within the temporal domain. The following assessments
will be made:
Experiment 1: Perception of audiovisual temporal synchrony (an audiovisual
Temporal Order Judgment task (AVTOJ))
Experiment 2: temporal ventriloquism (a visual Temporal Order Judgment task
(VTOJ))

Design Exp 1. In the AVTOJ task, stimuli are artificial, natural (biological)
or social, resulting in three conditions. There are 10 SOAs per condition,
ranging from -800 to +800 (with steps of 100 and 50ms). These 30 unique trials
are randomly presented 16 times in four blocks of 120 trials each.

Design Exp 2. The VTOJ task has five conditions (silent control, and clicks at
audiovisual delays of ~100 ms, ~200 ms, ~300 ms and ~500 ms). The visual
flashes are presented at 10 SOAs ranging from -600 ms to +600 ms with steps of
100, 50 and 25 ms. This results in 50 unique trials, each randomly presented 16
times in five blocks of 160 trials each.

As far as we can consider there are no risks related to this study. Therefore
we do not foresee any difficulties that could lead to any medical, mental or
physical problems. There is a mental load, but this is minimized by conducting
the experiments on two different days and each experiment can be stopped for a
break.

Participation in this study implies that one contributes to the development of
(fundamental) knowledge about multisensory processing within the temporal
domain as a possible underlying deficit in social interaction and communication
in children (and people in general) with autism. For the future, the outcome of
this study could have practical and clinical implications for the treatment of
autism.

This study is group-related, because it could not be conducted without the
participation of adolescents with autism (all belonging to one group). We would
like to acquire more knowledge on differences in (multi)sensory processing
between autistic and healthy children and the suggested multisensory deficits
in autistics, present at childhood age. Therefore, we include autistic
adolescents in our study to examine whether multisensory temporal deficits are
indeed a core problem and whether these deficits are manifest at that age.