The Autism Research Team (ART)
have been conducting an exciting new MIRAGE project funded by the British
Academy/Leverhulme small grant scheme.
The team investigated whether children with and without autism spectrum
disorders (ASD) respond to multisensory illusions in the same way and whether
susceptibility to illusions changes with age.
MIRAGE illusions rely on multisensory integration which is important not
only for allowing us to perform simple movements (e.g. pointing) but also for
developmental processes. These include distinguishing between the self and
others, and developing a sense of body ownership. Such processes are necessary for the
development of more complex social behaviours, including empathy and imitation,
which individuals with ASD have difficulties with. Research exploring multisensory
integration in ASD could give us a better understanding of the social problems
in autism and how these could be remediated.
Participants aged between 5 and 15
years placed their right hand into the MIRAGE system and saw two images of
their right hand on the screen (the supernumerary limb illusion). One image was
always in the same location as the real hand while the other was to the right
or left of the real hand.
Children felt their hand being
stroked with a paintbrush and saw one hand being stroked in time with the felt
strokes, while the strokes on the other hand were delayed. A picture then
appeared above each hand and children were asked which picture was above their
real hand.
In past experiments, adults nearly
always state that the hand being stroked in time with the felt strokes (the
synchronous hand) is the real one, even when this image is not in the same
location as their actual hand. This is due to the adults
integrating the visual and tactile information, creating a strong sense of
ownership over the synchronous hand.
View of the hands in the MIRAGE as used for the experiments
In the current experiment, children aged
between nine and 11 years showed similar results to adults, as did seven and
eight year olds, but less strongly than the older children. Interestingly, four
to six year olds did not chose the synchronous hand significantly more often
than the asynchronous one. This suggests that the multisensory integration
necessary for this illusion to occur develops throughout childhood.
Overall, children
with ASD tended to choose the synchronous hand. This is in contrast to previous
research which has suggested that individuals with ASD may be less susceptible
to multisensory illusions such as the rubber hand illusion (RHI). In the RHI,
ownership of a fake hand is induced by providing temporally congruent seen and
felt touches on a fake hand and the participant’s real, hidden hand respectively.
These contrasting
findings could be due to the MIRAGE illusion requiring less language
comprehension, attention and imagination than the RHI. To investigate this,
further MIRAGE experiments are being conducted as part of a PhD by Katie
Greenfield, a member of the ART, with a larger number of individuals with
Autism.
Post written by Katie Greenfield
