27/22 (19–25), task and gaze were randomly allocated to subjects142 | Direct counting, 2 | Highest during conversation
Lowest during visual acuity (visual task) and the reduction is proportional to the attentional demand of mental task
Difficulty of task had no influence on BF. However, BF depended on the position of the gaze |
70/80 (5–87), fixed order of tasks143 | Videotaping, 2½ | High at conversation
Low during reading
Most common pattern of BF in decreasing order was: conversation < rest < reading
Conclusion: BF does not depend on ocular conditions, age, and wear |
7/1 (21–29)144 | Measure of biopotential at canthi | Significant decrease while TRACON work became more difficult |
32/0 (18–32)145 | Measure of biopotential at canthi, 40 | Blink duration and eyelid closure increased during task
An increase when the attentional process wane |
22 students146 | Measure of biopotential at canthi | Significantly higher for a difficult task than an easy arithmetic task
Unchanged if the task was a letter search |
29/20 (22–50)147 | Measure of biopotential at canthi, 3 | Reduction at visual task, but an increase during conversation
Substantial increase at mental loading and while memorisation
Dopamine activity correlates directly with BF |
16/0 (students)148 | Measure of biopotential at canthi, 32 | Lower at visual task than during auditory tasks, also lower blink duration |
20 students149 | Counting from television screen | An increase at difficult problems, significant differences between easy and difficult tasks
Internal stimuli may cause an increase, however only for easy tasks |
27/14 (20–42)150 | Measure of biopotential at canthi | High at conversation, oral proverb interpretation, memory recitation
Low at proverb interpretation by reading a card |
0/24 (19–20)151 | Measure of biopotential at canthi | Data suggest an inverse relation between BF and visual task difficulty |