Gender difference in seeing fast-moving objects suggests autism clue
Men see high-speed visual stimuli more quickly than women, and no one knows why. Ben Lewis reports.
When it comes to detecting quickly moving visual objects, men are faster than women, according to research published in the journal Current Biology.
But it might not be due to better visual processing, say researchers from the University of Washington in the US. Instead, it could be due to the same brain processes as those found altered in autism spectrum disorder (ASD).
The result caught the researchers, led by Scott Murray, by surprise, because, on average, men and women perform similarly on most cognitive tests.
The effect was identified, serendipitously, while Murray and his colleagues were studying processing differences in people with ASD.
The scientists were using a task in which people had to report whether black and white bars on a screen were moving to the left or to the right.
ASD shows a large sex bias, with boys being about four times more likely to be diagnosed than girls. Because of this, Murray’s included gender as a factor in their analysis of a control group, comprising volunteers who didn't have ASD.
As soon as they looked at the control data, the difference between men and women immediately emerged.
Men were able to complete the task and make the right call on the direction of the lines in only a tenth of a second, and often much less. However, women regularly took about 25 to 75% longer.
The researchers then double-checked with other teams who had used the same test, and found the effect was consistent across studies.
Exactly why men can pick up the movement of high-contrast stimuli quicker remains a mystery. The scientists say it can't be explained by general differences in the speed of visual processing, overall visual discrimination abilities, or potential motor-related differences.
One possibility is that the improvements could be tied to more frequent computer gaming by males. However no other improvements that would normally be expected from playing on computers were seen.
Curiously, the results showed the same gender-based performance difference between men and women with ASD. And that has the authors speculating that men may have reduced gain-control, a neural mechanism that regulates the neural responses to high contrast stimuli. The hypothesis suggests that males with ASD have an even greater reduction in that process.
Discovering why the detection difference exists, the researchers say, could provide clues to the gender bias in people with ASD.
See how you do on the visual test: