Task-induced stress and motivation decrease foveation-period durations in infantile nystagmus syndrome.
OBJECTIVE
To investigate the effect of visual demand, task-related physiological stress, and motivation on the nystagmus waveform of 19 subjects with infantile nystagmus syndrome (INS).


METHODS
Subjects viewed a Landolt C of varying orientation and size, and indicated its orientation via arrow keys on a keyboard. Mental arithmetic was performed in conjunction with the visual task. Subjects then underwent a reward-penalty paradigm. Eye movements and heart rates were recorded during all experiments.


RESULTS
Task-related physiological stress and motivation were reflected in an increase in heart rate and led to an increase in the amplitude, frequency, and intensity of the nystagmus waveform and a decrease in foveation-period durations. Changes in heart rate did not correlate with changes in waveform parameters for all experiments.


CONCLUSIONS
The results show, for the first time, the negative impact of task-induced stress and/or motivation on the characteristics of INS. This finding has important implications for individuals with INS, because stress may arise in everyday situations, such as driving or when undertaking an examination.
Cham
Kwang M
KM
Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, Victoria, Australia.
Anderson
Andrew J
AJ
Abel
Larry A
LA
D000293:Adolescent; D000328:Adult; D002908:Chronic Disease; D005133:Eye Movements; D005260:Female; D005584:Fovea Centralis / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009042:Motivation; D020417:Nystagmus, Congenital / Q000503:physiopathology* / Q000523:psychology*; D013312:Stress, Physiological / Q000503:physiopathology*; D013315:Stress, Psychological; D013997:Time Factors