Answer:
Overt
Step-by-step explanation:
There are two types of attention: overt attention and covert attention.
OVERT ATTENTION is when an individual's eyes is directly focused on something while the covert attention is when an individual is focused on something without moving he eyes and thus seeing something accessorily.
Therefore, the use of eye trackers can only reveal the shifting of one's overt attention and not ones covert attention because eye trackers focus on the movement of the eyes.