A Functional Near-Infrared Spectroscopy Study of Sustained Attention to Local and Global Target Features

Abstract

There has been extensive research investigating the differences between global and local feature discrimination. The role that global and local feature discrimination has in sustained attention tasks however has been relatively neglected. In the current research, participants were required to perform a sustained attention task requiring them to engage in either global or local shape stimuli discrimination. Reaction times to local feature discrimination revealed a quadratic trend with time-on-task, with performance levels showing a decline before returning to initial levels towards the end of the task. This trend was not found in the global shape discrimination condition. Functional near-infrared spectroscopy (fNIRS) was employed to assess hemispheric cerebral oxygenation during the tasks. It was found in both conditions that there was greater oxygenation in the right hemisphere compared to the left hemisphere. It was also found that right hemisphere oxygenation increased with time-on-task. Left hemisphere oxygenation decreased during the global task, while it increased during the local task with time on task. Total cerebral oxygenation, collapsed over both hemispheres, increased more over time in the local discrimination task than the global discrimination task. The performance data and the fNIRS results suggest an increased utilization of bilateral cognitive resources with time-on-task in the local discrimination condition, but not in the global discrimination condition. Results and implications are discussed.