Saturday 10 September 2022

This is your rationality on drugs

Are people less rational (or, perhaps, more rational) when affected by drugs? We know that alcohol affects decision-making (see here and here). But, what about other drugs? This 2018 article by Gillinder Bedi (University of Melbourne) and Daniel Burghart (California State University Sacramento) looks at the effect of THC (the psychoactive component of cannabis) and MDMA (ecstasy) on the rationality of decision-making in a lab experimental setting. Specifically, they look at:

...whether choices satisfy the generalized axiom of revealed preference (GARP) after decision makers have been orally administered THC... MDMA, and a placebo.

The generalised axiom of revealed preference (GARP) essentially says that if a consumer chooses Bundle A rather than Bundle B when both are available and affordable, then the consumer should always prefer Bundle A to Bundle B when both are available and affordable. So, if prices of available income change, and Bundles A and B both remain available, the consumer shouldn't switch their preference. It sounds simple, but experimental studies often show that people violate this axiom over the course of many choices.

Bedi and Burghart have a sample of 15 research participants, who each completed three experimental sessions, with each session seven days apart. In one session, the participant received 10 mg per 70kg body weight of THC, in another session they received 1.5 mg per 70 kg body weight of MDMA, and in another session they received a placebo. This is what we refer to as a within-subjects research design, because all of the comparisons of experimental groups and control groups are comparing the same people in each condition. The order of conditions was randomised for each research participant. To measure rationality, each participant was asked to select from a set of bundles of cash and 'social time' (which they could 'spend' later in the experimental session on accessing their cell phone later in the (seven hour!) experimental session. There were 11 different 'budget lines', so I think that means that each research participant made 11 choices in each experimental session. The results are fairly clear though, with Bedi and Burghart finding:

...little perturbation from unity (i.e. perfect GARP compliance). Indeed, in just three instances... [out of 43] are AEIs less than 0.999. Pairwise t-tests all fail to reject the null of a difference in average AEI between treatments.

The AEI is their measure of the extent of deviation from rationality. So, it appears that people are just as rational when affected by THC or MDMA as when they are not. At least, for this particular measure of rational decision-making (GARP). There are less serious but much more common violations of rational behaviour that Bedi and Burghart didn't assess. For example, it might be interesting to look at the sunk cost fallacy (are intoxicated people more (or less) affected by sunk costs?), or loss aversion (are intoxicated people less loss averse?). Alternatively, looking at altruistic or cooperative behaviour would also be interesting. Some ideas for future work, perhaps (and certainly more serious than getting crayfish drunk)?

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