According to Thomas and Irwin in Perception & Psychophysics 2006, 68 (3), 475-488:
Blinks occur on average once every 4 sec, or 900 times per hour, and the average blink duration is approximately 250 msec; thus, a total of 1 h out of every 16âh waking day is spent blinking.
During this time we see absolutely nothing that's going on around us - but what's even more crazy is that many cognitive functions (iconic memory for example) are suppressed shortly before, during and after the blink.
Someone decided to see what he was missing during a blink and created a crazy device that takes pictures whenever he blinks.
The BlinkCam uses custom-built soft conductive thread and conductive fabric swtitches that complete the circuit of the hacked shutter-release button. The thread and fabric is affixed to the face with spirit gum and the simultaneous closing of both eyes triggers the camera to take a picture.
For more info about the blink cam go here.
This is particularly interesting since some of my own research focuses on the impact of blinking on perception. See below the fold for a related abstract.
When a visual target is displaced during a saccade the perception of its movement is suppressed. Its movement can usually only be detected if the displacement is quite large. This suppression of displacement can be eliminated by introducing a short blank period after the saccade and before the target reappears in a new location. This has been termed the "blanking effect" and has been attributed to the use of extra-retinal signals to compare the old location of the target to the new. We examined whether similar effects occur with eye blinks or other visual distractions. We found that suppression of displacement can also occur due to a blink and that introducing a blank period after the blink eliminates the displacement suppression in much the same way as after a saccade. However, the blanking effect does not occur when other visual distractions are used.