ALTHOUGH it may not seem a matter of great importance at first glance (no pun intended), the matter of why we blink so often is quite an interesting question.
It is commonly agreed that blinking acts to cleanse the eye and also to protect it under certain circumstances. It is also claimed that normal blinking is an aid to good vision.
However, psychologists have also studied blinking and have come up with the interesting theory that blinking is intimately connected to thinking, and is the mind's way of punctuating thought.
When you blink, the eye lids close and then retract, coating the eyes in a film of tears. This cleans and polishes the outer surface of the eye and also rinses out any debris that is adhering to the eye.
In order to carry out this cleaning action, we need blink only once or twice a minute. However, we blink 15 times per minute on average, and 15,000 times per day. This would seem to be far in excess of what is required to keep the eyes clean, and suggests that blinking also serves other functions.
If you stare fixedly at an intense light source, your eyes will be damaged. However, we are all equipped with an involuntary reflex action which protects us in this regard.
If your eye is surveying a scene and suddenly, without warning, encounters an intense source of light, the eye will immediately close in an involuntary reflex blink. It is also argued (e.g. The Art of Seeing, by Aldous Huxley, Triad/Panther Books, 1985) that frequent relaxed blinking is an essential aid for optimum vision. This is a fascinating little book written in Huxley's inimitable razor sharp style.
In the 1920s it was noted that rates of blinking vary according to the tasks a person performs. People blink less frequently when performing wholly visual activities e.g. dot to dot drawing.
People blink more often when tired than when resting. People blink more frequently when excited, when angry and when speaking. Such observations suggested a connection between blinking and the mind.
There are several forms of blinking. There is blinking which cleanses the eyes, blinking associated with being startled (say, by a loud and blinking to indicate anger or amazement.
The term endogenous blinking indicates the type that - is neither voluntary nor precipitated by being startled. Since the 1970s, endogenous blinking has been closely studied by psychologists.
It was noticed that increasing alertness reduced the rate and the duration of blinks. For example, a pilot in a flight simulator blinks only half as often as when sitting in the co pilot seat.
The blink interval is also shorter for the pilot than the co pilot. You may also notice that you blink more often when driving on a quiet open road than when driving down a busy street. You may also have is when performing a potentially dangerous operation, for example when overtaking a long truck on the highway.
On the other hand, psychologists have determined that when you are bored you not only blink somewhat more frequently, but the eyes remain shut during the blink about 30 per cent longer than normal.
Rates of blinking also change with different levels of anxiety. Learner drivers blink more often than instructors. It has been noted that witnesses confronted by unfriendly attorneys blink more rapidly than those facing friendly lawyers.
It is interesting to note the rate of blinking of politicians and others during television interviews, as it is a sensitive indicator of levels of anxiety. Television news casters are instructed not to blink in order to appear controlled and calm.
Psychologists seem to have established a definite link between blinking and memorising. When subjects are asked to memorise - series of letters, they are most likely to blink shortly after considering the information to be stored.
The greater the number of letters be memorised, the greater the time elapsing between presentation and blink. The blink appears to occur at the point when the memory forms and when the brain anticipates no further material.
THERE is also a relationship between decision making and blinking. In a typical experiment subjects are asked to identify short tones and long tones. They blink before the end of a long tone but after the end of a short tone.
Obviously the decision that a tone is long can be made before the tone is finished. This is not possible with a short tone, and the brain will wait an instant after the tone has stopped in order to be sure.
In other words, the brain structs the eye to blink when it satisfied it has made a decision. Something in reading. You are most blink when your eyes reach the end of a line.
It seems that the brain likes to pause between discrete sensory episodes. The blink indicates the pause - a kind of mental punctuation.
The blink can be visualised either as a comma or a full stop.
When you drive down a busy city street your blinks are brief and infrequent. This can be as dividing up the fist changing images presented to you into manageable chunks.
During memorising and decision making, blinks last longer and are more frequent. These blinks are like full stops and provide more definite interruptions of the inflow of visual information, thereby allowing the brain to organise the information as simply taking it in.