Humans blink in response to environmental demands: study

Humans unconsciously trade off the loss of information during a blink with the physiological urge to blink, a study suggests.

Blinking is an omnipresent involuntary process that maintains stable and healthy vision. With 15 blinks per minute on average it is one of the most frequent human actions, researchers from Technische Universitat Darmstadt in Germany said.

However, during a single blink, our visual perception is interrupted for about a third of a second, they said.

Although our conscious perception suggests a continuous and stable world, about 10 percent of the time we are missing potentially important visual information from our surroundings.

For this reason, it is advantageous, whether for our ancestors roaming the savanna or the modern human crossing a busy road, to coordinate our blinking intelligently.

Previous studies have revealed an intriguing multitude of additional factors influencing human blink rates.

Blinking is closely intertwined with cognitive functions connected to dopamine, a neuromodulator involved in reward-related behaviour and learning.

In particular, blink rates are elevated when we are tired and are related to our activities, as they go up when we are talking and go down when we are reading.

While blinking is clearly related to these cognitive processes, so far it has been unknown, how blinking relates quantitatively to properties of our environment.

Researchers led by professor Constantin Rothkopf from Technische Universitat Darmstadt, showed for the first time quantitatively, how blinking is related to environmental task events.

Participants in an experiment were instructed to detect short events presented on a computer monitor. The probability of an event occurring was systematically modified by the researchers to reveal participants' blinking strategies.

Participants learned the hidden regularities of the visual events and progressively improved their performance of detecting the events.

The analysis of the blinking behaviour showed that participants unconsciously blinked less and less the more probable they believed an event was about to occur.

"The computational model we have developed is able to reproduce this behaviour," said PhD student David Hoppe, first author of the study.

"As the model also contains physiological parameters, which differ between individual participants, it is possible to predict the likelihood of times between two successive blinks," Hoppe said.