In the blink of an eye – research on blinking as by-product of mental processes

Susan Chollar

In the Blink of an Eye

Some people value eyes as windows to the soul. Others find eyelids more revealing. Nine hundred times an hour, three hundred million times a lifetime, the blink of an eye can tell much about what’s going on in a person’s mind.

Some blinks protect the eyes, others lubricate the cornea. Infants blink for only these reasons; studies of newborns have established that the reflex to moisten and clean the eye occurs only once every two minutes. From infancy on, however, the blink rate steadily increases until, at puberty, people reach a blink-rate plateau–an average of about 15 blinks a minute–which they maintain for the rest of their lives.

The vast majority of these blinks serve no physical function but are by-products of mental processes, says psychologist John A. Stern of Washington University in St. Louis, a pioneer in the study of blinking. Using everything from electrodes to infrared cameras, researchers have shown that the frequency, duration and timing of blinks are influenced by a wide range of physical and mental states.

Tasks involving visual activity decrease blink frequency, particularly when concentration is required. Pilots blink less frequently than copilots do, and drivers blink less often while maneuvering through crowded city streets than they do on lonely stretches of highway.

“When information acquisition in important, you actively inhibit your blinking,” Stern says. While driving a car, for example, people routinely blink as they check their speed–once when they shift their eyes to the speedometer and once again when they return their eyes to the road. However, if they notice a police car hot on their tail, people hold off on the blink as they glance toward the speedometer. The same holds true for checking the rear-view mirror. A routine check is accompanied by a blink, but peope do not blink when they are trying to change lanes.

Increased blinking is often a sign of physical or psychological stress. People blink more when angry or excited, for example. And one of the earliest studies in blink research determined that anxiety can increase the blink rate: While courtroom witnesses were under hostile cross-examination they blinked much more frequently.

Richard Nixon is a case in point, says Stern, who first became interested in blinking during the Watergate era. “President Nixon’s blink rate markedly increased when he was asked a question he was not prepared to answer,” Stern says. “His speech was well-controlled and did not manifest other symptoms of anxiety, but you could see it in his eyes. Most politicians have learned to disguise feelings except in ways they cannot inhibit.”

State-of-the-art blink research involves monitoring each phase of a blink — measuring how long it takes the lid to close, how long the eye stays closed and how quickly the lid reopens. Each portion of the blink can act as a telltale clue to what kind of shape the blinker is in. Fatigue, alcohol and drugs make blinks less crisp, and drowsiness can increase the time the eye remains closed by 50 o 80 milliseconds.

The Air Force is studying blinking as a potential tool for monitoring the alertness of such personnel as pilots and flight controllers. In one study conducted at the Air Force School of Aerospace Medicine, pilots deprived of sleep flew for four and a half hours in a flight simulator. The researchers found that the frequency and crispness of the pilots’ blinks were both good indicators of how many mistakes they would make.

Impaired performance claims thousands of lives in automobile accidents every year. Stern thinks that blink monitors built into cars would save many lives. “I want a light on the top of every car and truck that will indicate when a driver is not performing safely,” he says.

Blink monitors also may someday serve as useful checks for boredom, a condition that proves dangerous in demanding jobs. Blink frequency and blink duration both increase when workers are bored. “Man is not a good animal for maintaining vigilance,” Stern says. “We want to determine what we can do to reduce the likelihood of pilots, air traffic controllers, automobile and truck drivers and nuclear plant operators missing important events.”

Most recently, Stern has turned his attention to another aspect of blinking. “We blink at times that are psychologically important,” Stern says. “Blinks are punctuation marks. Their timing is tied to what is going on in our heads.” Stern and others in the field are using blinks as clues for studying the sequence and timing of the mental events involved in acquiring and processing information.

Blinks, for example, seem to occur at definite points in decision-making processes. “During a mental task, blinks tend to occur during moments of decreased attention, marking a temporary cessation of information intake,” Stern says.

Bursts of blinks also mark the transition from one stage of processing to another. If asked to multiply 12 times 15, an individual will blink as each part of the mental problem is solved. Blinks appear to mark brief breaks that the brain takes at the end of each phase of a mental task.

“Blinks are a window into our thought processes,” Stern concludes. Think about that the next time you find yourself staring into someone’s eyes–you may do better reading their mind than pondering the depths of their soul.

COPYRIGHT 1988 Sussex Publishers, Inc.

COPYRIGHT 2004 Gale Group

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