Table 5.

Frequency of used observed eye movement related variables.

Code in Appendix A	Eye movement related observed variables	Frequency
GL_num	number (frequency) of glances to a specific target or area of interest in a set time period	49
GL_adur	average duration of glances to a specific target or area of interest in a set time period	44
GL_patt	glance or fixation patterns or heat map	31
FIX_num	number (frequency) of fixations on a specific target or area of interest in a set time period	27
VAR_hor	variance of horizontal range of fixations	26
GL_%	percentage of glances to a specific target or area of interest in a set time period	25
FIX_adur	average duration of fixations on a specific target or area of interest in a set time period	24
GL_tot	total time spent glancing on a target in a set time period	23
GL_%t	percentage of time glancing to a specific target or area of interest in a set time period	21
GL_over	number or percentage of glances over a set threshold (most often 2 seconds)	19
VAR_vert	variance of vertical range of fixations	19
GL_max	longest duration of a glance to a specific target or area of interest in a set time period	18
OTHR	other measures	17
SACC	saccade measures - duration, speed, amplitude...	17
FIX_tot	total time spent fixating on a target in a set time period	14
GZ_andev	deviation of gaze angle from a set point (most often the center of the road)	13
PUP_size	average pupil size (diameter) in a set time period	13
FIX_%	percentage of fixations on a specific target or area of interest in a set time period	12
FIX_%t	percentage of time fixating to a specific target or area of interest in a set time period	10
BL_rate	blink rate in a set time period	10
TTFF	time to first fixation to the target or area of interest	7
BL_dur	blink duration	5
FIX_max	longest duration of a fixation to a specific target or area of interest in a set time period	4
FIX_over	number or percentage of fixations over a set threshold (most often 2 seconds)	1