Drivers’ Eye Movement Characteristics in a Combined Bridge-Tunnel Scenario on a Mountainous Urban Expressway: A Realistic Study

Table 2

Experiment index.

Eye movement	Unit	Meaning
Pupil diameter	mm	Direct expression of visual perception represents the degree of mental load of the subject
Blink count	N	BC reflects the degree of fatigue
Average blink duration	s	When sleepiness occurs, the blink rate becomes slower and the average blink duration becomes longer
Fixation count	N	The more the time of fixation, the more interested and important the information is in the area of interest
Average fixation duration	s	The time spent on each gaze is a factor of attractiveness, indicating the degree of interest of the subject.
Total fixation duration	s	Total fixation duration reflects the user’s interest in information
Saccade count	N	Represents the attraction of an object
Average saccade duration	s	Refers to the time when the visual perception of the subject changes from perception to cognition
Viewpoint trajectory	—	It can fully interpret the behavior patterns of the subjects to help explore the psychological activities of the users