The movement of light: how the autistic brain processes the world
Imagine walking around, sitting down, or standing still, but being unsure if you, or the world around you, is moving. Dr Susan Morris, School of Physiotherapy and Exercise Science, theorises that this may be the unsteadying experience of some people on the autism spectrum, who have sensory processing challenges.
World-renowned autism advocate, livestock-handling equipment designer, author and public speaker, Dr Temple Grandin, regularly lectures on how people on the autism spectrum process the world differently to their neurotypical counterparts, and the impact of sensory processing challenges on the emotional, behavioural and motor functioning of individuals with an Autism Spectrum Disorder (ASD). Dr Morris is leading a research team examining how optic flow, the movement of light across the retina, may underpin some of these challenges in functioning.
Autism Spectrum Disorder (ASD) is a lifelong neurological difference, which can affect sensory processing, speech development, fine and gross motor skills and social communication. ASD is a complex condition and, alongside their challenges, some people on the spectrum have been reported to have unique abilities. A great attention to detail, and the capacity to focus intensely on specific passions and talents are two of the hallmarks of ASD.
2012 figures from the Australian Bureau of Statistics show that 115,400, or 0.5 per cent of the Australian population, have an ASD, while figures from the US Department of Health and Human Services Centers for Disease Control and Prevention indicate 1 in 68 children in the United States is identified with an ASD. The National Disability Insurance Agency’s 2015 Quarterly Report to COAG Disability Reform Council [.pdf] noted that people on the spectrum are the largest disability group within the National Disability Insurance Scheme, with 31 per cent of participants being diagnosed with ASD.
With her research project, Dr Morris, and her research student Yi Huey Lim, are aiming to develop a better understanding of how autistic people experience the world. Their study focuses on the interpretation of optic flow, and how this impacts balance and movement. And while ASD is currently identified and diagnosed [.pdf] via specific developmental and behavioural criteria, this understanding may ultimately point to a biomarker for ASD in some individuals and, critically, assist in its early identification.
“When optic flow is interpreted correctly, we can distinguish when the world is moving around us compared to us moving around in the world,” Dr Morris said.
“If optic flow is not integrated in the nervous system in a typical way, then self-motion may be difficult to discern from movement of objects in the world. This might explain the observed poorer motor coordination and balance we see in people with ASD.”
Dr Morris’ research team, which includes Associate Professor Hoe Lee, School of Occupational Therapy and Social Work, Professor Torbjorn Falkmer, Faculty of Health Sciences, Professor Garry Allison, Office of Research and Development, Professor Tele Tan, School of Civil and Mechanical Engineering, and Master of Philosophy student, Yi Huey Lim, collaborated with Curtin’s Hub for Immersive Visualisation and eResearch (HIVE) on Visual Fields and Balance in People with Autism, which ran from March to June 2016.
The collaboration ensured the study participants, which included autistic and neurotypical adults, could access authentic experiences via the controlled virtual environment of the dome. The participants were completely immersed in a star studded universe, which is similar to the technology used in science fiction films to simulate a spaceship moving through the stars.
“The collaboration involved the expertise of the HIVE staff and Dr Wee Lih in projecting three-dimensional static and dynamic stimulus on the 180-degree dome display screen. The dome screen allowed maximal display of the fields of view in a virtualisation environment, allowing participants to experience real-life and immersive situations in a controlled study environment,” Dr Morris said.
“When a neurotypical person experiences the stars flowing into the screen, which is an illusion that they are moving backwards, they automatically react by leaning forwards. They do the opposite for stars moving out of the screen. By reversing the flow of stars, and limiting the field of view to peripheral vision only, full view and central vision only, we could compare the automatic motor responses to optic flow in people with and without ASD.”
Dr Morris and her research team noted some surprising responses to the virtual environment from the ASD population of the research group.
“It seems that while neurotypical adults can ignore optic flow that is just in the periphery, that is, they interpret the moving stars in the periphery to be a moving picture and not themselves moving, the adults with ASD responded as if they were moving. This suggests to us that people with ASD may not be able to use visual cues appropriately to determine whether the world is moving, or they are moving. This would make life quite difficult for people with ASD, and may explain why they become overwhelmed easily.”
While the study has provided some fascinating insights into how some autistic people process their environment, Dr Morris believes the results may also ultimately prove helpful as an indication of ASD in both children and adults, and could assist with early diagnosis of autism in children.
“If differences are still present in adulthood, this indicates that the problem persists through life. We have found some very significant and large differences in behaviour in the ASD group, and the test may prove a useful biomarker for ASD,” Dr Morris said.
The early diagnosis of ASD, and intervention for the condition, is critically important. It is known to improve a child’s long term developmental outcomes, and reduce costs to families, individuals and societies. In the research paper, ‘The cost of autism spectrum disorders’, the financial impact on individuals with ASD, and their families, is estimated to be approximately $34,900 per annum. 90 per cent of that sum is associated with parental loss of income from unemployment and the remaining 10 per cent is due to appropriate access to intervention and delay in diagnoses.
Dr Morris said the Curtin Autism Research Group, in particular Professor Torbjorn Falkmer, was critical to the establishment of the study. Dr Andrew Woods, Jesse Helliwell and Joshua Hollick at the HIVE, Dr Wee Lih Lee, School of Occupational Therapy and Social Work, and Aiden McIntosh, Engineering Support Services, also provided invaluable support to the project.
Dr Morris has a particular interest in understanding how people on the spectrum experience the world. She believes ASD is a sensorimotor disorder, and symptoms result because people with ASD experience the world in a very different way to neurotypical people. She would like to be able to help people understand what it is like to be autistic, and to find ways to make negotiating a neurotypical world easier for people with ASD. Her study, Visual Fields and Balance in People with Autism, ran from March to June 2016. One of Dr Morris’ earlier papers, ‘Differences in the use of vision and proprioception for postural control in autism spectrum disorder’, can be read here.