Waterboarding the Brain – The Neural Effects of Enhanced Interrogation Techniques

The Question of Morality vs. The Question of Efficacy

The recent Senate Intelligence Committee report detailing the CIA’s use of enhanced interrogation techniques (EITs) like waterboarding has reinvigorated debate over the appropriateness of such methods for counterterrorism efforts. Many protest the use of EITs on moral or legal grounds, citing the inhumanity of the physical and emotional pain imparted by these tactics. Further corroborating protesters’ arguments is ample scientific evidence demonstrating that the aversive effects of exposure to stressors like those involved in EITs are not limited to the duration of those experiences. Instead, enduring high stress circumstances can lead to life-long struggles with post-traumatic stress disorder (PTSD), anxiety, and depression, effects that are likely mediated by physiological changes in the amygdala, an area of the brain that processes emotional information.

Given the harm associated with EITs, it is perhaps important to assess whether EITs provide the desired outcome of enhancing national security. Indeed, harming an individual to spare no one is morally distinct from harming an individual to save many. Though we may determine that neither case is acceptable, the former case is clearly less acceptable than the latter.

Unfortunately, the actual impact of EITs is not clear. Defenders of EITs claim that EITs are critical tactics that have helped the United States thwart terrorist attacks, while opponents argue that the techniques have not significantly contributed to actionable intelligence. Because there are few data that can be used to address the efficacy of EITs as they are currently employed, it may be helpful to draw upon behavioral science research to identify any potential for these EITs to fulfill their stated goal of extracting valuable information.

Are Enhanced Interrogation Techniques Effective?

What are the critical brain processes that determine whether a prisoner will divulge constructive information to his interrogators?

Memory – To convey accurate information, memory must be intact.

Some arguments against the efficacy of EITs have focused on the deleterious effects of stress and sleep deprivation on memory and have pointed to imaging studies that suggest that people suffering from PTSD have different patterns of activation in areas of the brain involved in memory compared to those without the disorder. These arguments emphasize the potential for those undergoing EITs to supply false information.

Much of the literature on the effects of stress and sleep deprivation on memory actually show that these factors influence working memory and diminish the ability to learn new information. However, it is possible that memories of the past could also be affected, particularly if those memories are complex or not stably encoded in the brain. Nonetheless, it is unlikely for stress to demolish highly engrained information. Given that such information, such as the names of family members or close friends, may be valuable for counterterrorism, arguments against the efficacy of EITs that are built on the impact of stress on memory are perhaps not highly convincing.

Executive Functions – The surrender of withheld information may be facilitated by disruption of executive functioning.

The scientific research that is probably most relevant to the efficacy of EITs is that addressing the effects of stress on executive functions. Stress significantly affects the prefrontal cortex (PFC), which is critical for these functions. Executive functions that are likely relevant for those undergoing EITs are the disciplined control over behavior and the ability to keep track of different versions of fact sets.

When the PFC is damaged, people have a harder time regulating their behavior and tend to resort to behavior that is more habitual and less goal-oriented. Thus, it could be argued that the stress-induced diminution of discipline could increase the likelihood that withheld information becomes shared. Nonetheless, there is no evidence to suggest that the extreme measures that appear to accompany EITs are necessary to induce the type of stress needed for this effect.

Motivation – Choosing to share information requires that one deem the value of sharing that information as higher than the value of not sharing that information.

If we consider the effects of EITs on motivation and valuation, the argument of their effectiveness begins to crumble. Stressful circumstances, particularly those that may be interpreted as life threatening, elicit what is known as the fight or flight response, in which the body’s physical and mental resources are focused on escaping or demolishing the perceived threat. In the case of EITs, these responses likely manifest as instincts to survive and to avoid pain.

Some researchers have suggested that those enduring EITs are motivated to talk because time spent talking is time where interrogation, and the associated stress and pain, are avoided. These researchers further claim that there is little correlation between the accuracy of information provided and the degree of pain endured. When this is the case, there is clear incentive to talk but no added value of providing truthful information. Even if we could articulate how EIT practices could incentivize the sharing of accurate information, the argument for the justification of EITs would still suffer from our inability to illustrate how these practices are superior to others that would be considered more civilized.

How Can We Ensure National Security Without EITs?

Behavioral science suggests that the potential for EITs to lead to the acquisition of accurate actionable intelligence is limited. Thus, there is great potential to develop a new system for procuring desired information that is superior to current EITs in both a moral sense and a practical sense.

A significant weakness of EITs is that they are not conducive to scientifically rigorous experimentation. Ethical considerations prevent us from conducting controlled human studies on the impact of EIT implementation, which precludes optimization of these approaches. However, research from a number of disciplines, including neuroscience, computer science, psychology, and economics provide considerable insight into how to affect decision making. If we apply this knowledge to build new innocuous systems for interrogation, we have the opportunity to collect data and optimize these systems accordingly.

In addition to providing general information on the efficacy of specific negotiation tactics, this type of research could also uncover details on how to customize interrogation to individual cases. For example, neuroscience research demonstrates that stress differentially affects male and female decision making tendencies, suggesting that different coercive approaches could be strategically targeted to men and women.


It is difficult to condone EITs given that the aversive neural effects do not appear to be accompanied by significant societal benefits. Further, even if we could establish moral grounds for EITs, our focus should be on how to effectively obtain the information we need to keep our citizens safe. EITs are not conducive to science-backed optimization because they do not allow for controlled experimental manipulations. On the other hand, other persuasive tactics, which may be equivalent or superior to EITs in their efficacy, can be experimentally tested and improved upon as more data are collected. Employing the scientific method to understand specific effects of different coercive techniques could allow us to more effectively acquire the information needed to keep our nation secure.


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Image via jerryjoz / Shutterstock.

Nisha Cooch, PhD

Nisha Cooch, PhD, is a Senior Contributor to Brain Blogger. She holds a PhD in neuroscience and is an expert in the neural basis of decision making. You can follow her on Twitter @NishaKCooch.
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