Author: tomstafford

The BPS has published a discussion paper on “Neuroethics”. Neuroethics is an unnecessary phrase which covers a hodge-podge of ethical concerns for psychology researchers and broader societal concerns over the application of findings from the cognitive neurosciences.

The paper, prepared by the impressive team of Carl Senior, Patrick Haggard and John Oates, is mostly a discussion of the particular ethical issues that might arise from research using cognitive neuroscience techniques such as fMRI. Overall, it seems to me that all of the substantive ethical issues mentioned by the paper are treated at length by existing moral philosophy (and in particular by medical ethics). It is not clear that psychology and neurosciences have anything to add, which should be a first clue that the idea of “neuroethics” is inherently dubious.

A particularly revealing moment is the authors’ discussion of the evidence showing that people are more likely to believe an explanation when it is presented alongside a picture of a brain scan (McCabe & Castel, 2008 – covered on Mind Hacks here). This, for the authors of the discussion paper, raises the spectre of BPS members having “undue influence” by accompanying their explanations with pictures of brain scans.

In light of the persuasive power of brain scan imagery its use to illustrate any fact should be restricted as much as possible. Brain scan imagery should not be included on recruitment posters for participation in experiments

Here, the authors seem to have been affected by a peculiar version of the very effect they are warning against! They treat influence due to brain imagery as somehow exceptional, in the same way that people in the experiments treat explanations using brain imagery as somehow exceptional. Consider how the argument would look if it was a prescription against accompanying your communications with partcular phrases, or with offers of financial rewards. The way explanations are phrased affects how often they are believed – that does not mean psychologists should not try to be persuasive, nor that they are wrangling the minds of the public in an exceptional way if they are. There is evidence that monetary rewards, like brain imagery, can distort people’s judgement (see, e.g., Hsee, Zhang & Zhang, 2003) – the BPS has not recommended that members can’t pay people to participate in experiments.

It is part of normal cognitive function to be affected by the environment, and there are many quirks about the way we humans are affected by the exact content and structure of the environment. Examples of that influence are not automatically examples of “undue influence”, regardless of whether they involve brain imagery or not.

There are genuine ethical issues which are peculiar to cognitive neuroscience, but our duty to attend to these is better served by seeing brain related issues in the context of general ethics, rather than pandering to the kind of exceptionalism that the phrase “neuroethics” encourages.

A discussion paper: neuroethics and the british psychological society research ethics code

Hsee, C. K., Yu, F., Zhang, J., & Zhang, Y. (2003). Medium maximization. Journal of Consumer Research, 1–14.

McCabe, D. P., & Castel, A. D. (2008). Seeing is believing: The effect of brain images on judgments of scientific reasoning. Cognition, 107(1), 343-352. doi:16/j.cognition.2007.07.017

In which I suggest applying the methods of experimental psychology to a longstanding question in political science.

Many people feel that there is no “real difference” between political parties (for example, Labour vs Conservatives in the UK). Politians are all the same, right? At least superficially, mainsteam parties will all echo commitments to values such as “community” and “education” and positions such as “tough on crime” and “for a strong economy”.

In perceptual psychology we have a number of methods of calculating how accurate and sensitive a sense, like sight or hearing, is. Using these ‘psychophysical’ methods you can come up with a number which allows you to compare across different senses, or across different people. So, for example, we could show that vision is more sensitive than hearing, or that your vision is more sensitive than mine (or even that your vision is more sensitive than my hearing). These methods account for things like base-rate biases in people’s responding (so, for example, it could account for the fact that you might be more likely to say you can see something when you are in doubt, while I might be more likely to say that I can’t when I am in doubt). This sensitivity statistic I am thinking of is called d’ (“d prime”) by psychologists.

I’ve been considering whether these methods from perceptual psychology could be used to address the question of how similar the positions of political parties are. My way of testing and tracking the difference in the stated policy positions of the parties would work like this: you take a standard public expression of party positions (election manifestos?) and sample policy statements (size of sample to be decided, somewhere between individual sentences and paragraphs). Then, after coding the statements for their year and origin, you anonymise them and ask voters to say which party they think the statements come from. With a few psychophysical calculations we can then come up with a sensitivity statistics which reveals how easy voters find it to distinguish the policy positions of the two parties, and we can then compare how this changes over time, or in different policy areas.

Friend and political scientist Will Jennings, told me that – of course – political scientists already look at this topic. The British Election Study has been asking voters since 1964 how close the parties are. Projects such as the Comparative Manifestos Project have coded party manifestos from around the world, using techniques such as automated coding of text and expert surveys (i.e. asking academics what they think).

The problem with asking voters how close the parties are, or to code the parties as more “left-wing” or more “right-wing” is that you deal with opinions of voters, not their actual ability to discriminate between the positions of the parties. The problem with coding the manifestos is that it puts a layer of intepretation (as to what counts as left-wing, or converservative, or whatever) before you can judge one manifesto as closer or further away from another.

My psychophysics approach tests directly the ability of voters to discriminate between stated policy positions. We do this by presenting many small fragments of the manifestos and asking a participant to judge which party they are from. By gathering many many judgements we can get a sense of how likely they are to name each particular party (i.e. their bias) and get a sense for how likely they are to be correct (i.e. their sensitivity). We combine these, accounting for any bias towards naming a particular party, to get an estimate of their ability to discriminate between the parties based on their stated policy positions. You can average this index across people, removing random variation in sensitivity between people, to get an estimate of how discriminable two stated positions truly are.

Cross-posted, with some informed comment, at The Monkey Cage

At the University of Sheffield we’ve been teaching psychology using lego robots. This isn’t as peculiar as it might sound. You can learn a lot about your theories by trying to build them into a machine or computer programme. But while teaching the course, I discovered that you can also learn a lot about the methods used in experimental psychology by trying them out on robots.

This is one of the lego robots we were using. They are built using a Lego Mindstorms set and inspired by a book by Valentino Braightenberg called ‘Vehicles: Experiments in Synthetic Psychology‘.

The robot has a light sensor on each side and a nose-bumper which tells it when it has hit something. A simple brain connects these sensors with two independently powered wheels. Here’s the robot in action:

The suprising thing, and a crucial point of Braitenberg’s book, is that you can get what looks like complex behaviour (in this case line following) from simple rules. All that governs this robot’s behaviour is a positive connection between each light sensor and the wheel on the same side. This makes the robot turn away from lighter floor patches, so in this environment it traces the edge of the patten. An additional ‘fixed action pattern‘ makes it spin around and start in another direction if it bumps into something.

Many people look at these robots and over-intepret the complexity of their behaviour. You need skepticism and controlled experiments to discover exactly how simple the rules controlling the robot are. However, while I was trying to use the robots to teach this to my class, the robots and the class conspired to teach me something.

In a more advanced class I put a simple learning rule in the robot’s brain so that they could learn to slow down before hitting walls (actually, it is only true that I put the rule in the robot’s brain in the sense that Hitler invaded Poland. In truth I made a grad student programme the rule into the robot. Thanks Stuart!).

The task I set the class was simple, I thought: run an experiment to see the robot learn over successive trials. Because I’d programmed the rule into the robot I thought I’d be able to predict the robot behaviour. The predicted learning curve of the robot looked like this:

The results from the groups looked like this

Since each robot was identical – same body, same brain in the way only robots can be – and all the groups were doing the same experiment, I expected to get the same results from each group. No luck there! Some get an increase, but with some the line stays almost flat. Some it goes up smoothly, some get wild swings in performance up and down.

And this got me to thinking. If the results are this variable with experimental subjects which we understand completely – their simple bodies are made of lego for goodness sake! the brains are identical and programmed by us! – how unreliable will results be if you experiment on real people? Noisy humans have bodies and brains which are both vastly more complex than lego robots, and each body and brain is unique. With so many sources of variability between individuals it ios amazing that experimental psychologists ever get any results at all.

The moral is that experimental work is hard, really hard. You’d better be sure your experiment reduces sources of variability as much as possible because there will be enough uncontrollable variability without you adding any more.

Fortunately there is a light at the end of the tunnel, in the form of statistics. If you average the different noisy group results you get something a bit more like the underlying pattern I knew to be there:

Trying a simple experiment with the lego robots gave me a new respect for the experimental method, and the difficulty psychologists face when trying to discover the rules underlying the wonderous variety in human behaviour.