Helton, W.S., Warm, J.S., Tripp, L.D., Matthews, G., Parasuraman, R., & Hancock, P.A. (2010). Cerebral lateralization of vigilance: A function of task difficulty. Neuropsychologia, 48, 1683-1688.
Functional near infrared spectroscopy (fNIRS) measures of cerebral oxygenation levels were collected from participants performing difficult and easy versions of a 12 min vigilance task and for controls who merely watched the displays without a work imperative.