Eye Tracking.

Eye-tracking research provides designers with a blueprint of sorts to guide them on the priorities with which site visitors generally absorb the information on any given site.

F-Shaped Pattern For Reading Web ContentNielsen Norman GroupNovember 12th, 2017
Eye Tracking: Best Way to Test Rich App UsabilityUX MagazineDecember 8th, 2011
A Brief History of Eye-TrackingUX BoothJanuary 19th, 2010
Eyetracking: Is It Worth It?UX MattersOctober 19th, 2009