Has anyone succeeded in measuring where the focus is between saccades? Through some kind of nonintrusive brainscan perhaps? I would like to be able to draw with my thought :) (Something similar would be okay, like the position or shape I am thinking of overlayed on what I see)
The retinal image cannot be refocused on an intermediate target during a saccade.
Psychophysical experiments have shown that during a saccade, attention is aimed at the target location. Instructing the subject to make a saccade from location A to C, while focusing on another point B proved impossible.
The authors conclude that:
[A] saccade executed to a peripheral location in the visual field involves the orienting of attention to that location, prior to the actual execution of the saccade. The inability to orient attention to one location and simultaneously execute a saccade to another location suggests that orienting of attention may be an essential component of preparing and/or executing saccades.
In other words, a saccade is meant to shift the point of focus, and attention cannot be paid to another point during a saccade.
Because of perisaccadic space compression effect, the focus lies inbetween from the saccade onset position to its future offset (target position), but only given the target is inside this region.
In case the target changes its position during saccade; or was not inside it from the start (antisaccade task), there is no compression effect and, therefore, no objects are focused.