Researchers from Alabama have solved the mystery of why we don鈥檛 notice ourselves blinking.
Each time we blink, we hardly notice the interruption because we switch off the visual areas in our brain that normally first register darkness, they say.
Timothy Gawne and Julie Martin of the University of Alabama in Birmingham examined how monkeys鈥� brains respond when the world goes dark.
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Normally, special cells in the V1 area of the cortex respond with a sudden burst of activity. This explains why a brief period of external darkness is startling. The burst emphasises the sudden change from light to dark, they believe.
But when the darkness is caused by a blink, the V1 cell activity is somehow suppressed and there is no burst. Gawne believes that this is triggered by the motor signal that sets off the blink in the first place. That signal may also tell us not to pay attention to the lack of activity, giving us the impression that the visual world has not changed.
Smoothing over the gap
Some researchers think that visual cells somehow smooth over this gap in activity, giving the impression of a continuous image during a blink. 鈥淣eural activity should span the gap,鈥� says Gawne. However, his work shows that is not the case.
鈥淭he apparent continuity of visual perception during a blink does not depend upon continuity of neuronal activity in all of the neurons,鈥� says Gawne. Instead it seems only requires the absence of a signal that something has changed.
The researchers are now trying to establish whether the same suppression process happens during saccadic eye movements.
This research was presented at a conference in New Orleans, organised by the US-based Society for Neuroscience. 快猫短视频鈥檚 full coverage of the conference is here: www.newscientist.com/conferences/
For more about how you don鈥檛 see all that you might think, see: 鈥淏lind to change鈥� in 快猫短视频 magazine, 18 November 2000.