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Tuesday, February 25, 2014

Autism and the Average

From Cracking the Enigma

By Jon Brock
February 14, 2014

Around this time every year, my almost-namesake, John Brockman, publishes on his website, Edge, a selection of answers to an Annual Question. What have you changed your mind about? What is your favourite deep or beautiful explanation? What should we be worried about?

This year's question was particularly intriguing. What scientific idea is ready for retirement? Diverse answers include: big data, universal grammar, entropy, string theory, radical behaviourism, common sense, carbon footprints, neuroplasticity, the continuity of time, the idea that science is self-correcting.

My favourite response, however, came from Nicholas Christakis, a physician and social scientist at Yale University. His answer: the Average.

"Ever since the landmark invention of diverse statistical techniques 100 years ago that allow us to properly compare the difference between the averages of two groups, we have deluded ourselves into thinking that it is such differences that are the salient—and often the only—important difference between groups. We have spent a century observing and interpreting such differences. We've become almost obsessed, and we should stop."

As an autism researcher, this is an issue particularly close to my heart. Despite the incessant talk about the "heterogeneity problem" in autism research, most autism studies begin and end with the question of whether or not on average people with autism are different on some measure to people who don't have a diagnosis.

This carries with it the assumption that it is the average (and not the variation around the average) that matters; that it captures some essential property of autism. It also invariably leads to contradictory findings, where one study finds some interesting difference on average between autistic and non-autistic people - and another finds no difference or even the opposite effect.

My latest article for the Simons Foundation Autism Research Initiative elaborates on this point. It was inspired initially by a wonderful essay by Stephen Jay Gould, discussing life-expectancy statistics in the context of his own background in evolutionary biology. As Gould wrote:

"All evolutionary biologists know that variation itself is nature’s only irreducible essence. Variation is the hard reality, not a set of imperfect measures for a central tendency. Means and medians are the abstractions."

This, I argue, is an important lesson for autism research.

"We have to take heterogeneity seriously as the object of investigation, rather than an excuse for inconsistent results or an inconvenience in our quest to understand the essence of autism."

The search for autism's core essence is something that has driven research ever since Kanner first described autism in 1943. However, seventy years later, we're still not much closer to an answer - as evidenced by the controversies surrounding the latest attempt to redefine autism in DSM-5.

There's no denying that "autism" is a useful meme in terms of raising awareness and in communicating in very broad terms the kinds of difficulties a person may face. "Autism" also serves an important purpose in bringing together likeminded people for support, advocacy, and research.

"...given the incredible diversity within autism, it's not clear that autism is an actual thing to be explained either."

Clearly, the symptoms that affect people diagnosed with autism are real and for many present huge challenges. However, autism is not an explanation for those challenges - it is those challenges. And given the incredible diversity within autism, it's not clear that autism is an actual thing to be explained either.

So, inspired by John Brockman, my question to you is this: Are we now at the point where, as a scientific concept, "autism" is ready for retirement?

About Jon Brock

Jon Brock is a research fellow at the ARC Centre for Cognition and its Disorders at Macquarie University in Sydney, Australia. His research focuses on cognitive and neural mechanisms involved in developmental disorders including Autism, Williams Syndrome and Down Syndrome. Publications can be downloaded here.

As well as on his own blog, Brock has also written for the Simons Foundation Autism Research Initiative, the Thinking Person's Guide to Autism and The Conversation. Translations of some of his posts can be found on the Spanish-language website Autismo Diario.

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