Summary and Critique by: Jared Leets
Scher, Zeithamova, and Williams begin by stating that the domains affected by sleep deprivation tended to involve complex integrating tasks. These tasks demand flexibility, innovation, and decision-making. There has been plenty of literature focusing on the role of decision-making in the prefrontal cortex. The article examined neural and cognitive changes in association with sleep deprivation. Subjects performed the decision-making tasks while undergoing fMRI scanning in the morning after getting 7-9 hours of sleep and then again at the same time on
Day 2 after remaining awake for 24 hours. Fifteen students participated in this study most of them from West Point and the remaining students attending the University of Texas. A PC-compatible laptop computer presented the visual images using a LCD projection system that was behind the MRI projecting a screen mounted in the bore 16 inches from the participant’s eyes. Participants viewed the images through a mirror placed on the MR head coil and responded to the task, via controllers given to them in their right hand.
Stimuli for the three decision tasks were novel abstract shapes. Every task asked participants to match perceptually similar shapes. In the two-alternative forced-choice task, participants viewed a shape on the top of the screen simultaneously with two test shapes on the bottom of the screen and were asked “Which one?” The participants’ task was to point to which
of the two shapes matched the exemplar shape. The subjects received information explaining that the shapes were hand-written scripts in a foreign language and would not match exactly. In the integrative decision, the task consisted of one exemplar shape and two other shapes with the question in the middle saying, “Exactly one?” The participants had to say either one or only one, of the test items were equal to the exemplar item. For every task there was a time limit, typically 3.6 seconds, and when the time limit passed the display was replaced with a blank screen until the new trial began.
The results indicated that a participant’s ability to make integrative decisions drastically declined from Day 1 to Day 2. The calculation t(11) =2.50,p< .05. The alternative forced-choice task significantly declined as well, t(12) = 2.66 p< .05, but not nearly as much as the integrative decisions. In the end complex decision making that asked its participants to integrate multiple matching decisions was impaired by a large margin.
The researchers received the answer they were likely expecting. The prefrontal cortex was where the decision making occurred and where the lack of sleep affected the subjects. Overall the experiment was a success and proved to be a significant contribution to research on sleep deprivation and how it affects decision-making. It showed how important sleep is when it comes to making complex decisions on the spot.
Source: Schnyer, D. M., Zeithamova, D., & Williams, V. (2009). Decision-making under conditions of sleep deprivation: Cognitive and neural consequences. Military Psychology, 21(S1), S36. http://cognem.uoregon.edu/files/2014/10/Decision-making-under-conditions-of-sleep-deprivation-Cognitive-and-neural-consequences-152m10o.pdf