Repeatability of the timing of eye-hand coordinated movements across different cognitive tasks

Quantification of eye-hand coordinated behaviour is a relatively new tool to study neurodegeneration in humans. Its sensitivity depends on the assessment of different behavioural strategies, multiple task testing and repeating tasks within one session. However, large numbers of repetition trials pose a significant burden on subjects. To introduce this method in large-scale population studies, it is necessary to determine whether reducing the number of task repetitions, which will lower subject burden, still leads to acceptable measurement accuracy. The objective of this study was to investigate the validity and reliability of eye-hand coordination outcome parameters in eight healthy volunteers using a test-retest approach. Subjects were assessed during a shortened test procedure consisting of eight repetitions of three behavioural tasks: a reflex-based tapping task, a planning-based tapping task and a memory-based tapping task. Eye-hand coordination was quantified in terms of timing (eye and hand latencies), kinematics and accuracy. Eye and hand latencies were found within a normal range (between 150 and 450ms). A paired samples t-test revealed no differences in timing parameters between the first and second measurements. It was concluded that eight trial repetitions are sufficient for quantifying eye-hand coordination in terms of timing, kinematics and accuracy. This approach demonstrates the testing of multiple visuomotor behaviours within a reasonable time span of a few minutes per task.