Experimental Neuroethics

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Photo credit: Timothy Epp, Shutterstock

Four years ago, Neil Levy gave the concluding lecture at the first Brain Matters conference in Halifax. He alerted the audience of neuroethicists to the fact that the field of philosophy was undergoing a revolution – rather than muse from their armchairs in the ivory tower, a group of renegade philosophers were carrying out real experiments, asking people what their intuitions were about central issues in philosophy. Dubbed experimental philosophy, the new initiative was met with more than passing resistance from traditional philosophers. The apostate experimental philosophers responded by developing a logo of a burning armchair.

The landmark experiment was carried out by Josh Knobe, and its findings subsequently became known as the Knobe effect (you can watch a great recreation of the phenomenon in this YouTube video). Essentially, what Josh did was repurpose an old method from social psychology called the contrastive vignette technique (CVT) [1]. At its simplest, the CVT involves designing a pair of vignettes that carefully describe a particular situation (in the case of experimental philosophy, one that is often morally charged) but crucially differ in one detail, hence the term contrastive. Respondents see one and only one version of the vignette, and are then asked questions about what they have just read, with responses commonly recorded as a numerical rating on a Likert scale. By comparing the averaged responses between separate groups of people who have read the vignettes, the experimenter can systematically investigate the effects of small changes (of which the respondents are entirely unaware) upon attitudes towards nearly any topic. The experimental philosophers tend to use the technique to explore the meaning of concepts. Neil Levy pointed out that this same approach could, in principle, be applied to the full range of issues in neuroethics.

Neil’s presentation struck me like a thunderbolt. I had come to the field of neuroethics with a background in cellular and molecular biology, and had spent much of my career as a card-carrying reductionist: as a graduate student in the 1980’s, I championing the then-novel technique of recording from single neurons in freely moving animals, and as a postdoc I moved on to the better controlled (if less naturalistic) technique of patch clamp analysis of identified neurons in slices of brains. My subsequent rise through the ranks of academia was one in which I applied quantitative rigor to every question that I asked, and in the circles in which I traveled, this was lauded as the ultimate way to provide reproducible (and by inference, meaningful) results. I saw at once that the CVT opened the door towards doing something similar in the field of neuroethics.

My research group at the National Core for Neuroethics has embraced the use of contrastive vignettes wholeheartedly, and with a nod to the experimental philosophy camp, we call the approach Experimental Neuroethics. The team is applying the technique to a range of issues in contemporary neuroethics, probably best exemplified by our recent publications exploring public attitudes towards cognitive enhancement [2] as well as the acceptability of overt and covert nudges [3].

If the vignettes appear simple, I can assure you that properly crafting them is hard work. We begin with a carefully considered hypothesis and regularly find that the hypothesis morphs substantially (usually into something much more insightful) as the process unfolds. We then compose two or more contrastive vignettes, working hard to have the vignettes as minimally contrastive as possible (one word differences between vignettes is the ultimate goal, but this is often not feasible). Finally, we develop questions; we like to have the wording of the questions always be identical irrespective of the contrastive nature of the vignette.

Then the real fun begins. After a day or two, we assemble as a team and attack our previous work. Inevitably, we find it wanting in some respect. Sometimes, embarrassingly so. We find it best to begin by asking whether the vignette and the questions directly address the hypothesis. Sometimes that means that the hypothesis changes. Nearly always, that means that the vignette changes. This process is repeated again and again, over days and weeks and sometimes months (yes, and even sometimes years!) until we have a set of vignettes that get to the heart of the matter.

At some point late in the process we carry out cognitive pre-testing. This involves sharing the vignette and the questions with someone who has no particular expert knowledge (friends of friends are likely culprits), and debriefing them about what they read. We are sometimes amazed to find that what we intended for people to glean from a vignette is at odds with their reading of the vignette. That sends us back to the drawing board.

We also run some metrics to determine whether the words we have used are understandable by a general audience. We use online readability tests such as this one to establish the educational level required for understanding the vignette; our goal is that no more than a high school education is required. Finally, we launch the survey, recruiting respondents from amongst the thousands of people who have signed up on Amazon’s Mechanical Turk – they’re more representative of the real population and aren’t as blatantly WEIRD as typical undergraduate samples. And then we hold our breath.

Once the data is analyzed, we get mired once again in deep discussion. For it is not just the quantitative aspect of Experimental Neuroethics that it satisfying (to me), but also that the data gives us an entirely new benchmark for engaging in the process of wide reflective equilibrium. Throughout this process we remain aware that an ought can not derive from is, but having the data at hand, our version of ought is very much informed by the is. Ultimately, our data emerge in concert with our normative insights, and then one more advantage of Experimental Neuroethics is realized: it is easy for others to replicate our experiments, or even to improve them by taking our vignettes and modifying them to further test their own. This iterative process of replication, critique, and systematic modification has proven to be a robust strategy for advancing insights into the nature of biological and physical phenomena. Only time will tell whether Experimental Neuroethics catches fire in our discipline as it has in the field of philosophy (where it remains controversial). If it does, we can trace it back to Neil’s presentation in Halifax….

[Cross posted at the Neuroethics Blog]


[1] Burstin K, Doughtie E, Raphaeli A. Contrastive Vignette Technique: An indirect Methodology Designed to Address Reactive Social Attitude Measurement1. Journal of Applied Social Psychology. 1980;10(2):147–65.

[2] Fitz NS, Nadler R, Manogaran P, Chong EWJ, Reiner PB. Public attitudes toward cognitive enhancement. Neuroethics. 2013 doi: 10.1007/s12152-013-9190-z.

[3] Felsen G, Castelo N, Reiner PB. Decisional enhancement and autonomy: public attitudes towards overt and covert nudges. Judgment and Decision Making. 2013;8(3):202–13.

Me trumps We

Neuroessentialist thinking seems to be seeping into popular discourse more and more with each passing day.  Consider this.

When you buy something, you want to get the best deal possible. The internet has made that easier than ever, with online comparison shopping allowing consumers to shave dollars off the purchase price by comparing the costs at competing retailers. One of the remarkable ‘benefits’ of online retailing, it has also allowed for a loophole that represents a moral dilemmas that we must each evaluate.

The loophole in question is the ability of online retailers to avoid charging customers sales tax, at least in the United States (here in Canada, online retailers, charge local taxes). The loophole arises because retailers are allowed to forego charging state tax to out-of-state residents. Amazon, the Goliath of online sales, appears to be everywhere, but legally is nowhere (well, nearly so – it is obviously in Seattle, where headquarters reside). As a result, in most states, Amazon charges no state tax. If you buy their products and are not charged tax, you are supposed to declare it yourself.  And you do that, don’t you? Continue reading

Does the Science of “Prosocial Behaviour” Smuggle in a Political Prior?

Over at Pharyngula, PZ Myers’ reliably lively ScienceBlogs province, a recent post offers some incisive treatment of a philosophically arresting debate between Sam Harris and sundry interlocutors, most prominently Sean Carroll. The topic – whether science can answer moral questions, or, more perilously rendered, whether one can, in fact, derive “ought” from “is” – exerts a tidal attraction upon my blogging muscles, but I can resist for now; Myers’ relevance to this entry issues specifically from a choice bit of phraseology in his write-up.

When Harris claims that the discernment of human well-being (and hence of utility-maximizing courses of action) is a purely empirical matter, Myers finds him guilty of “smuggling in an unscientific prior in his category of well-being.” What I want to explore after the jump is the following possibility:

It may be that the developing body of work in neuroscience and psychology probing various morally charged phenomena has been smuggling in a politically loaded prior under the terminologically neutral guise of the category “prosocial behaviour.”

Continue reading

Hope for humanity after all

01-money-exchangeRobert Wright, author of such thoughtful books as A Moral Animal and The Evolution of God, has an op-ed piece in the Sunday New York Times entitled, “A Grand Bargain over Evolution“.  Without considering the merits of his contentious argument that moral laws exist in the some absolute sense and that we humans discover them as we go along (much like we have discovered the laws of thermodynamics), there was one part of his essay which caught my eye.

“There are plenty of evolutionary biologists who believe that evolution, given long enough, was likely to create a smart, articulate species — not our species, complete with five fingers, armpits and all the rest — but some social species with roughly our level of intelligence and linguistic complexity.

And what about the chances of a species with a moral sense? Well, a moral sense seems to emerge when you take a smart, articulate species and throw in reciprocal altruism. And evolution has proved creative enough to harness the logic of reciprocal altruism again and again.

Vampire bats share blood with one another, and dolphins swap favors, and so do monkeys. Is it all that unlikely that, even if humans had been wiped out a few million years ago, eventually a species with reciprocal altruism would reach an intellectual and linguistic level at which reciprocal altruism fostered moral intuitions and moral discourse?

There’s already a good candidate for this role — the chimpanzee.

Chimps, some primatologists believe, have the rudiments of a sense of justice. They sometimes seem to display moral indignation, “complaining” to other chimps that an ally has failed to fulfill the terms of a reciprocally altruistic relationship. Even now, if chimps are gradually evolving toward greater intelligence, their evolutionary trajectory may be slowly converging on the same moral intuitions that human evolution long ago converged on.”

Yes, chimps have a rudimentary sense of justice, including some version of reciprocal altruism.  But in a 2007 paper in Science, Jensen et al. showed that there are moral decisions that humans make that seem to be absent in chimpanzees.  The findings have implications both for our understanding of what makes humans unique, as well as for economic decision making.

The experiment is a variant of the ultimatum game, and demonstrates a form of altruism called altruistic punishment.  Each of the players in this game get to make one decision.  Player 1 is offered $100, and has to decide how much of this windfall will be shared with Player 2.  As you consider this decision, you are aware that Player 2 is aware of exactly how much money you received.   Once you make your offer (all, some, or none) to Player 2, they get to decide if they view it as fair.  If the conclusion is yes, both of you get to keep your winnings; if they view it as unfair, both of you forfeit the money.

The game has been played many times with humans, and regularly works out like this.  If Player 1 offers $50 to Player 2, everyone is happy and Player 2 accepts the deal.  If the offer is only $40, Player 2 may not be happy but will accept it.  But at some point (usually around $20), humans consider low-ball offers so unfair that they will reject it, even if it means that they get nothing.  The idea is that this reaction punishes Player 1 for their chintzy behavior, but it comes at a cost to Player 2; after all, isn’t $20 better than nothing?  Apparently, the trade-off that our brains make is between money and moral outrage, and at 20%, moral outrage wins out. Because Player 2 is giving something up to achieve this outcome, this phenomenon is called altruistic punishment, and is evident in humans from diverse cultures, suggesting that this form of ethical behavior arose sometime before we spread out and (over)inhabited the entire planet.  Moreover, it is considered to be one of the ways in which we enforce social cohesiveness in human interaction. [For those of you wondering how altruistic punishment might work in real life, imagine a scenario where you are walking down the street and see a small person getting beaten by a big bully.  Classical altruism theory suggests that you would not intervene unless the little guy is related to you – essentially, a variant of the selfish gene hypothesis.  But that is not what humans do – they do intervene, not always but often and even at risk of personal injury, particularly when they perceive the fight as unfair.  This is altruistic punishment in action.]

It turns out that chimpanzees do not exhibit altruistic punishment when playing the ultimatum game.  At least under the conditions that Jensen et al. utilized, chimps readily accepted 20% of the pot (which consisted of raisins instead of dollars).  There are important constraints that are worthy of further exploration (see for example Neiworth et al, 2009), but the interesting point is this: social evolution has conferred on humans more complex moral intuitions than are seen in non-human primates.  It is not known at what point in our cultural evolution altruistic punishment arose, but it seems to me entirely plausible that it is a product of the specific social conditions under which humans have lived for some time.  In the midst of all the handwringing over the (sadly, many) ways in which humans mistreat each other, it is heartening to know that our magnificent brains have developed ways in which to make life with our fellow man more reasonable.  It appears as if there is hope for humanity after all.