Task-induced stress and motivation decrease foveation-period durations in infantile nystagmus syndrome

Abstract

Purpose: 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.