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TASK-INDUCED STRESS AND MOTIVATION DECREASE FOVEATION-PERIOD DURATIONS IN INFANTILE NYSTAGMUS SYNDROME.

Cham KM, Anderson AJ, Abel LA

Optometry & Vision Sciences, University of Melbourne, Carlton, Victoria, Australia.

Purpose: To investigate the effect of visual demand, task-related physiological stress, and motivation on the nystagmus waveform of nineteen INS subjects. Methods: Subjects viewed a Landolt C of varying orientation and size, indicating its orientation via arrow keys on a keyboard. Mental arithmetic was carried out in conjunction with the visual task. Subjects then undertook a reward/penalty paradigm. Eye movements and heart rates were recorded for all experiments. Results: Task-related physiological stress and motivation were reflected in an increase in heart rate; they led to an increase in the amplitude, frequency and intensity of the nystagmus waveform, and decreased foveation-period durations. Changes in heart rate were uncorrelated with changes in waveform parameters for all experiments. Conclusions: We have shown for the first time the negative impact of task-induced stress and/or motivation upon the characteristics of INS. This has important implications for individuals with INS, since stress may arise in everyday situations, such as driving or when undertaking an exam.

Published 8 April 2008 in Invest Ophthalmol Vis Sci.
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