The average human eye blinks approximately once every four to six seconds, or 15 to 20 times a minute. However, the frequency varies under different conditions. Blinking tends to decrease during times of concentration and increase in nervous or stressful situations.
Blinking also increases when a person is tired and decreases when a person is relaxed. Infants tend to blink less often than adults.
Blinking helps lubricate the cornea by spreading secretions from the tear glands over the exposed part of the eye. Other benefits of blinking include cleaning small dust particles and other foreign bodies from the eyes as well as to block out visual stimuli to aid in concentration.