Obviously, people blink in order to lubricate their eyes.
But that can’t be the only reason. We blink far more often than simple
moistening obligations would require. Plus, we seem to blink most at attention
break points—at the ends of written sentences or during pauses in speech. This
makes sense if you consider that each blink causes a momentary black-out of our
visual system. We’re blinking at times when we’ll miss the least amount of
information. Or are we looking at things the wrong way around? Researchers led
by Tamami Nakano of Osaka University showed that eyeblinks actually cause
attention disengagement rather than occurring after we’ve already briefly
disengaged.
In particular, the researchers were interested in two
regions of the brain: the dorsal attention network, which controls where we
focus our attention, and the default-mode network (DMN), which counteracts the
dorsal attention network and is involved in introspection. They placed ten
healthy volunteers in an fMRI while the subjects watched scenes from a TV show
(Mr. Bean). The subjects blinked an
average of 17.4 times per minute. They compared brain activity during the
spontaneous blinks to activity when the subjects were not blinking and to
moments when the screen was physically blacked out for the same duration and frequency
as normal eyeblinks.
Nakano T, Kato M, Morito Y, Itoi S, & Kitazawa S (2012). Blink-related momentary activation of the default mode network while viewing videos. Proceedings of the National Academy of Sciences of the United States of America PMID: 23267078.
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