The relation of cognitive load and pupillary unrest.
OBJECTIVE
This study examines the relationship between pupillary unrest (PU) and cognitive load.


BACKGROUND
PU represents a measure of reduced central nervous tonic arousal (sleepiness). A loss of tonic arousal can be associated with difficulties in maintaining the required level of performance. Thus, the measurement of tonic arousal in occupational contexts can help to prevent overload or errors.


METHODS
We compared a group with high cognitive load (30 apron controllers of an international airport) with a control group with low cognitive load (63 healthy people during their free time) in a non-randomized experimental design with pre- and post-test assessment of PU. PU was scanned by an infrared sensor with a frequency of 25 Hz and a resolution of .05 mm. To control for circadian effects, measurements for both groups were taken at the same time of the day.


RESULTS
High PU at the start of the shift correlated with high perceived load during the shift. There were no indications of reverse effects. Analyses of group x time effects with generalized linear models (repeated measures) revealed that cognitive load did in no way affected PU.


CONCLUSIONS
Initially low tonic arousal (indicated by high PU) may predict subsequent workload, but being exposed to high cognitive load does not influence tonic arousal after the end of the shift. With that, the study contributes to valid interpretations of pupillary unrest measurements in occupational contexts.
Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, Ludwig-Maximilians-University Munich, Ziemssenstr. 1, 80336 Munich, Germany. andreas.mueller@med.lmu.de
Andreas
A
Müller
Raluca
R
Petru
Lucia
L
Seitz
Ines
I
Englmann
Peter
P
Angerer
D000328:Adult; D000339:Affect / Q000145:classification / Q000502:physiology; D001359:Aviation; D003071:Cognition; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D011681:Pupil Disorders / Q000503:physiopathology*; D012025:Reflex, Pupillary / Q000502:physiology*; D014732:Vibration; D014851:Wakefulness / Q000145:classification / Q000502:physiology; D016526:Workload