A large percentage of veterans report symptoms of posttraumatic stress (PTSD) as a result of having been in or been exposed to combat situations. In fact, some reports suggest that among Iraq and Afghanistan veterans, the prevalence of PTSD is as high as one in five. Individuals who do not have clinical levels of PTSD, but only symptoms of PTSD, can also experience significant impairment due to their psychological state. PTSD symptoms are associated with hyperarousal, re-experiencing of traumatic events, avoidance of punishment, externalizing, and attempts to numb emotions.
However, the attainment of rewards and avoidance of punishments linked to PTSD were what Catherine E. Myers chose to focus on in a recent study. Myers, from the Department of Veterans Affairs New Jersey Health Care System, enrolled 48 male veterans with clinical PTSD or severe PTSD (PTSS) and 42 veterans without who served as control participants. The men were given two separate risk/reward tests. In the first task, stimuli were provided for the punishment, but not the reward. In the second task, positive feedback was given for the reward but there were no stimuli for the punishment.
Myers discovered that the PTSD and PTSS men scored more points overall than the control men. However, the PTSD/PTSS group outperformed the control group on the second task that provided positive stimuli and feedback for rewards, but performed slightly more poorly than the controls on the first task. Myers believes the PTSD/PTSS men were aroused by the possibility of reward and therefore exerted more effort in the second task. In the first task, Myers believes that the control group may have viewed the neutral reward as positive while the PTSD/PTSS men may have viewed neutral reward feedback as negative. This perception could explain why the control group outperformed the PTSD/PTSS group on this task.
These results are similar to other research efforts that suggest a bias toward positive outcomes in PTSD. “If this facilitation pre-dates onset of PTSD, then it might represent a pre-existing vulnerability that would bias an individual to develop PTSD following exposure to a traumatic event,” said Myers. However, it could be possible that the bias develops as a result of trauma exposure. Future work should explore this issue further to better understand the nuances associated with cognitive bias in PTSD.
Myers, C.E., Moustafa, A.A., Sheynin, J., VanMeenen, K.M., Gilbertson, M.W., et al. (2013). Learning to obtain reward, but not avoid punishment, is affected by presence of PTSD symptoms in male veterans: Empirical data and computational model. PLoS ONE 8(8): e72508. doi:10.1371/journal.pone.0072508
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