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Posted on March 14, 2019 at 7:52 AM

By Hazem Zohny and Tom Douglas

Scientists who want to study the effects of passing electric currents through prisoners’ brains have a PR problem: it sounds shady. Even if that electric current is so small as to go largely unnoticed by its recipient – as in the case of transcranial direct current stimulation (tDCS) – for some, such experiments evoke historical abuses of neuroscience in criminal justice, not to mention bringing to mind some of the more haunting scenes in films like One Flew Over the Cuckoo’s Nest and A Clockwork Orange.

And so, last week the Spanish Interior Ministry put on hold an impending experiment in two Spanish prisons investigating the impact of brain stimulation on prisoners’ aggression. At the time of writing, it remains unclear what the ministry’s reasoning for the halt is, though the optics of the experiment might be part of the story.

The experiment builds on another published by the same team earlier this year and involves measuring the impact of tDCS on the self-reported aggressiveness of imprisoned violent offenders. This entails stimulating the part of the brain related to decision making and social behaviour with a tiny electric current (1.5mA) for 15 minutes at a time. The current, halted study was meant to address some of the limitations of the first and had intended to include a non-imprisoned control group.

As the theory goes, enhancing the excitability of this part of the brain might help those disposed to aggression to better rein in these impulses. In the previous study, the imprisoned participants reported up to a 37% drop in feelings of physical aggression after 3 sessions of tDCS. In contrast, prisoners who only wore the electrodes without being administered the current showed no difference. (Typically in these ‘sham groups’ the current is administered only for a few seconds at the start of a session in order to mimic the brief tingling sensations associated with the onset of stimulation).

Of course, whether self-reported aggression tells us much about one’s actual disposition to be physically aggressive is open to question. The researchers had wanted to measure the impact of tDCS on cortisol levels—a less subjective proxy for aggression—but failed to get ethics approval for this.

There are a number of ethical concerns one might have about these types of experiments, though it’s unclear whether those played a role in the Ministry’s apparent ambivalence about this work. One looming issue is consent: can prisoner’s give it meaningfully, considering the coercive conditions they are in? Is being informed about the risks, signing a consent form, and being told they can withdraw at any time, sufficient?

The worry is that prisoners are generally highly incentivized to demonstrate a desire for rehabilitation – any evidence toward that end might be used to help them with, say, obtaining parole. Given how harmful being in prison can be for prisoners, it might be unreasonable for some to refuse an opportunity to participate in such an experiment, even if the likelihood it might reduce their sentences is remote.

This might indeed be a worry in the case of an intrusive experiment that entails some serious harm, or at least some risk of serious harm, to participants. For instance, if this were a deep brain stimulation experiment – which involves implanting a neurostimulator into the brain itself, along with all the associated risks of surgery – the question of attaining valid consent under such circumstances would indeed be paramount. But tDCS? Passing a 1.5mA current into the frontal cortex for 15 minutes a day for three consecutive days involves negligible risks. There is no evidence that unintended off-target effects (say, if an electrode is misplaced on the scalp) pose a risk from one session of tDCS  – instead, the most common side effects are slight tingling sensations and temporary skin redness where the electrodes were placed.

And this is relevant to consent: the importance of ensuring that consent isn’t coerced is related to the harm potential of what is to be done to someone. The greater the potential for harm, the more care we should take to ensure that all who agree to an intervention are doing so voluntarily. When the potential for harm is minimal, we might think that some risk of coercion can be tolerated in order to secure the benefits of research. Thus, many would think that some forms of low-risk medical research can justifiably be performed in prison settings, despite concerns that some prisoners may simply be agreeing to participate in order to please the prison authorities.

The other, and perhaps more serious concern here is what these experiments might entail – if successful – for prison reform, and indeed for crime prevention more generally.

For instance, the lead researcher on this project, Andrés Molero-Chamizo, told New Scientist that tDCS might be good for prisons themselves: “It could help to keep order inside a prison.” However, for many, prisons are long overdue for radical reforms in terms of how inmates are treated and the conditions they are kept it. We should not be supporting measures that put the burden of change on prisoners, we should be supporting measures that change the conditions that make prisoners hard to control to begin with – like overcrowding, for instance.

Moreover, some might argue that if these sorts of neurointerventions prove effective at altering offenders’ behaviours, this might relieve the much needed pressures driving social progress. Why bother understanding and amending whatever the underlying factors contributing to, say, domestic abuse or armed robbery, when we can instead merely alter the dispositions that led to those offenses?

These are valid questions, but it’s doubtful that they are decisive in this particular case. Firstly, it is a mistake to assume that individualised interventions, on the one hand, and the reform of prisons and wider society, on the other, are mutually exclusive. The two can, do, and often should go together. Perhaps we should solve problems like over-crowding and poor healthcare in prisons, and offer prisoners tDCS for aggression control.

Moreover, there is nothing suspect about behaviour modification in and of itself – that is precisely the goal of many existing rehabilitative efforts, like anger management courses and 12-step addiction programmes. Of course, if the end result of a brain stimulation intervention will be more than just a somewhat less impulsively aggressive prisoner, but one who has also lost crucial traits associated with, say, defending themselves or standing up for themselves, then that could be a serious moral concern.

But from what we know of the effects of tDCS, such a drastic effect seems unlikely. Incidentally, the halted study had intended to shed more light on whether tDCS would likely only reduce the aggression of those particularly disposed to it (such as violent prisoners, presumably), or whether it would have a similarly diminishing impact even on those who are comparatively less disposed to aggression. We’ll have to wait and see if the study is allowed to move forward.

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