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Marzieh Salehi Fadardi, Larry A. Abel; The Effect Of Cognitive Load On Saccadic Charactristics. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4865. doi: https://doi.org/.
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To determine how a concurrent mental arithmetic task induced stress and affected saccadic eye movement characteristics.
Reflexive saccades were recorded in 30 young normals (best visual acuity≥ 6/9) during a visually demanding task across gaze angles between ±25 deg, with 5 deg steps, during three task conditions while simultaneously recording heart rate. Subjects were requested to perform a reflexive saccade towards a visually demanding target and look back to the centre while target location and timing randomly varied. A fixed sized Tumbling-E was used as the eccentric target, with orientation identified via a gaming keypad. The time for manual response was limited while subjects were required to do verbalised arithmetic, continuously subtracting a given number between 100-150 by 7. Subjects then completed a similar task but without arithmetic and the response time was not limited. For the last task, eccentric targets were filled squares with neither manual response nor arithmetic required.
Means and SDs of the heart rate and saccadic variables are shown in Table1. Heart rate reflected task-induced stress, increasing significantly during the mental arithmetic task compared to the other task conditions (F=68.294, df=1, p<0.001). Similar results were found for the saccadic latency, which increased significantly with mental arithmetic (F=20.318, df=1, p<0.001). No significant effect of task conditions was found for gain (F=0.365, df=1, p=0.550) or asymptotic peak velocity (F=3.083, df=1, p=0.090).
A cognitively demanding secondary task affected saccade initiation without changing accuracy or peak velocity. A significant increase in heart rate supports the stressful nature of the dual task condition. Saccadic latency may reflect the level of mental workload in such tasks, which should also be useful in future studies of stress-related waveform and visual performance changes in infantile nystagmus syndrome.
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