You searched for: “tachistoscopic
tachistoscope, tachistoscopic, tachistoscopically
1. A scientific instrument used by psychologists which presents visual stimuli for a fraction-of-second exposures.
2. An apparatus that projects a series of images onto a screen at rapid speed to test visual perception, memory, and learning.
3. An instrument by means of which objects may be presented to the eyes for a brief measured period, a fraction of a second.

One of its principal applications being the measurement of the span of apprehension; that is, the amount of detail that can be apprehended by a single act of attention or perception.