Design: Participants performed a Sternberg working memory task where either one or four items were presented. After a brief period of time, a probe was presented and participants responded to whether or not the probe was a member of the previous Sternberg set. In one condition, the Sternberg task was performed on its own. In the other condition, the time between when the set was presented and when the probe was presented was filled with a visual attention task where participants responded quickly to the central arrow surrounded by distracting arrows. Both behavioral performance and electrophysiological recordings were used.
Hypotheses: Multitasking increases the demands on working memory and reduces the amount of resources available for cognitive control functions. It was expected that working memory deficits would be found in Veterans with PTSD and that the addition of a visually demanding attention task would increase the amount of errors in the PTSD group and diminish the electrophysiological component.
Results: Behavioral analysis found a significant main effect of group, indicating that PTSD patients performed with significantly less accuracy than the military controls. This was followed by a significant interaction that indicated PTSD patients were specifically impaired on the working memory task in the dual task condition. Electrophysiological results indicated that both the PTSD group and the controls showed similar brain patterns from 300 ms to 500 ms when discriminating old and new probes in the single-task condition. However, when taxed with the additional flanker task during the maintenance period, the ERPs of the PTSD group no longer differentiated old and new probes. The lack of differentiation in the ERPs reflects impaired WM performance under more difficult dual-task conditions.
Published in CABN - Honzel, N., Justus, T., & Swick, D. (2013). Post-traumatic stress disorder is associated with limited executive resources in a working memory task. Cognitive, Affective and Behavioral Neuroscience.
