Sniff a fragrant bunch of flowers and you're likely to linger over the perfume. Get a whiff of rotting fish and you'll pull your head away quick. Researchers have made the surprising discovery that children with autism show no difference when smelling a pleasant and unpleasant aroma.
Scientists in Israel now think that the way children sniff different smells could be used to test for autism. Thirty six children took part in the study, published in the journal Current Biology. A tube under their nose sent either pleasant or unpleasant odours while another recorded changes in breathing patterns.
According to PhD student Liron Rozenkrantz, children normally change the depth of their sniffing to the odours.
She told the BBC: "Children with autism didn't show this modulation at all - they took the same sniff for the smell of shampoo as they did for rotten fish."
The team created a special computer program which detected autism in the group of children with 81% accuracy. They found that the more severe the symptoms of autism, the longer the children inhaled the unpleasant smells.
It's now hoped that smell could be used as another way to test for autism. Dr Judith Brown, from the UK's National Autistic Society, said: "Getting a diagnosis is a crucial step to unlocking vital support services which can make a huge difference to people on the autism spectrum and their families.
"We believe that the possibility of developing a single and universal diagnostic test for autism is unlikely. However, in future, if these initial findings are confirmed and fully understood, differences relating to processing smell may offer an additional tool in the necessarily multi-faceted process of diagnosing autism."