An accommodation with the authority of common sense

In Science in Action, Bruno Latour talks of the birth of the modern science of geology, triumphed by Charles Lyell. He discusses Lyell’s attempt to professionalise and win respect for geology, and the need to find funds to support research in the new discipline. One solution to the need for funds it to appeal directly to the public, in Lyell’s case by writing a book that the landed gentry might read and so be convinced to donate to the cause of Geology:

If geology is successful in reshaping the earth’s history, size, composition and age, by the same token, it is also extremely shocking and unusual. You start the book in a world created by God’s will 6000 years ago, and you end it with a few poor Englishmen lost in the eons of time, preceded by hundreds of Floods and hundreds of thousands of different species. The shock might be so violent that the whole of England would be up in arms against geologists, bringing the whole discipline into disrepute. On the other hand, if Lyell softens the blow too much, then the book is not about new facts, but is a careful compromise between commonsense and the geologists’ opinion. This negotiation is all the more difficult if the new discipline runs not only against the Church’s teachings but also against Lyell’s own beliefs, as is the case with the advent of humanity into earth history which Lyell preferred to keep recent and miraculous despite his other theories. How is it possible to say simultaneously that it is useful for everyone, but runs against everyone’s beliefs? How is it possible to convince the gentry and at the same time to destroy the authority of common sense? How is it possible to assert that it is morally necessary to develop geology while agonising in private in the meantime on the position of humanity in Nature?


Replace 19th century geology with ‘cognitive sciences’, and gentry with ‘public’, and the essential tension is still there. The new brain science seeks attention and kudos, and in doing this must reach an uncomfortable accommodation with the ‘authority of common sense’. Psychologists and neuroscientists want to be heard in the public domain, but they will get so much more attention if they flatter received wisdom rather than attempt to overturn strongly held intuitions about human freedom, reasoning and morality.


Quote #290

Life shrinks or expands in proportion to one’s courage.

Anaïs Nin, volume 3 of her diaries (apparently)


Quote #289: There are no solutions here

There are no solutions here – it’s about what problems you choose to address on an ongoing basis

Rob Riordan, via @AlecPatton


I hear new news every day

I hear new news every day, and those ordinary rumours of war, plagues, fires, inundations, thefts, murders, massacres, meteors, comets, spectrums, prodigies, apparitions, of towns taken, cities besieged in France, Germany, Turkey, Persia, Poland, &c., daily musters and preparations, and such like, which these tempestuous times afford, battles fought, so many men slain, monomachies, shipwrecks, piracies, and sea-fights, peace, leagues, stratagems, and fresh alarms. A vast confusion of vows, wishes, actions, edicts, petitions, lawsuits, pleas, laws, proclamations, complaints, grievances, are daily brought to our ears. New books every day, pamphlets, currantoes, stories, whole catalogues of volumes of all sorts, new paradoxes, opinions, schisms, heresies, controversies in philosophy, religion, &c. Now come tidings of weddings, maskings, mummeries, entertainments, jubilees, embassies, tilts and tournaments, trophies, triumphs, revels, sports, plays: then again, as in a new shifted scene, treasons, cheating tricks, robberies, enormous villanies in all kinds, funerals, burials, deaths of Princes, new discoveries, expeditions; now comical then tragical matters. To-day we hear of new Lords and officers created, to-morrow of some great men deposed, and then again of fresh honours conferred; one is let loose, another imprisoned; one purchaseth, another breaketh: he thrives, his neighbour turns bankrupt; now plenty, then again dearth and famine; one runs, another rides, wrangles, laughs, weeps &c. Thus I daily hear, and such like, both private and publick news. Amidst the gallantry and misery of the world: jollity, pride, perplexities and cares, simplicity and villany; subtlety, knavery, candour and integrity, mutually mixed and offering themselves, I rub on in a strictly private life.

Robert Burton (1577-1640), The Anatomy of Melancholy (p.19)


Seeking help: Drawing machines

Matt is making a drawing machine. A robot which will live on a wall and plot out paths which are an algorithmic solution to the artistic seeds that Matt feeds it. I’m helping Matt, but we’re stuck with a bit of the maths.

Due to artistic and practical constraints, this is how the robot will work: there will be two motors, top left and top right, from which a ‘pen’ is suspended. Our problem is about how to change the length of the chains from which the pen is suspended to draw a straight line between two points. I’ve done a diagram to make this easier to explain. The crudely drawn black circles are the two motors. There is a small blue circle (a start point), and the two chains in green (with lengths l1 and r1 respectively. The target endpoint is show as a red cross, with the chains shown in purple (with lengths l2 and r2 respectively (obviously there are only ever two chains, one right and one left, not four).

Calculating the length of the chains at the start and the end is fairly trivial. The problem is at what rate to turn the motors to lengthen or draw in the chains to get between the start and the end points drawing a straight line. For artistic reasons it is absolutely essential that the line drawn between two points is straight.

I had a go at solving this. You can have a look at this python code (incidentally, my first ever python script!). The problem is, my solution makes curved lines, like this (points along the path shown as blue dots)

The chains need to be tightened by some amount during travel to stop a curve being described, but I know enough maths to know that I don’t have a hope of solving this one. Can you help?


Quote #287

Style is knowing who you are, what you want to say, and not giving a damn.

Gore Vidal, I’m told


Links for summer 2012


By the same impure urgency

I have no explanation for my own vile ambitions. Confronted with your pus, I could not stop to examine my direction, whether or not I was aimed at a star. As I limped down the street every window broadcast a command: Change! Purify! Experiment! Cauterize! Reverse! Burn! Preserve! Teach! Believe me, Edith, I had to act, and act fast. That was my nature. Call me Dr. Frankenstein with a deadline. I seemed to wake up in the middle of a car accident, limbs strewn everywhere, detached voices screaming for comfort, severed fingers pointing homeward, all the debris withering like sliced cheese out of Cellophane – and all I had in the wrecked world was a needle and thread, so I got down on my knees, I pulled pieces out of the mess and I started to stitch them together. I had an idea of what a man should look like, but it kept changing. I couldn’t devote a lifetime to discovering the ideal physique. All I heard was pain, all I saw was mutilation. My needle going so madly, sometimes I found I’d run the thread right through my own flesh and I was joined to one of my own grotesque creations – I’d rip us apart – and then I heard my own voice howling with the others, and I knew that I was also truly part of the disaster. But I also realized that I was not the only one on my knees sewing frantically. There were others like me, making the same monstrous mistakes, driven by the same impure urgency, stitching themselves into the ruined heap, painfully extracting themselves

F., in Leonard Cohen’s Beautiful Losers (1966), p.175

academic Me psychology

Fundamentals of learning: the exploration-exploitation trade-off

The exploration-exploitation trade-off is a fundamental dilemma whenever you learn about the world by trying things out. The dilemma is between choosing what you know and getting something close to what you expect (‘exploitation’) and choosing something you aren’t sure about and possibly learning more (‘exploration’). For example, suppose you are in a restaurant and you look at the menu:

  • Fish and Chips
  • Chole Poori
  • Paneer Uttappam
  • Khara Dosa

Assuming for the sake of example that you’re not very good with Sri Lankan food, you’ve now got a choice. You can ‘exploit’ – go with the fish and chips, which will probably be alright – or you can ‘explore’ – try something you haven’t had before and see what you get. Obviously which you decide to do will depend on many things: how hungry you are, how good the restaurant reviews are, how adventurous you are, how often you reckon you’ll be coming back ..etc. What’s important is that the study of the best way to make these kinds of choices – called reinforcement learning – has shown that optimal learning requires that you to sometimes make some bad choices. This means that sometimes you have to choose to avoid the action you think will be most rewarding, and take an action which you think will be less rewarding. The rationale is that these ‘sub-optimal’ actions are necessary for your long term benefit – you need to go off track sometimes to learn more about the environment. The exploration-exploitation dilemma is really a trade-off : enjoy more now vs learn more now and enjoy later. You can’t avoid it, all you can do is position yourself somewhere along the spectrum.

Because the trade-off is fundamental we would expect to be able to see it in all learning domains, not just restaurant food choices. In work just published, we’ve been using a new task to look at how actions are learnt. Using a joystick we asked people to explore the space of all possible movements, giving them a signal when they made a particular target movement. This task – which we’re pretty keen on – gives us a lens to look at the relation between how people explore the possible movements they can make and which particular movements they learn to rely on to generate predictable outcomes (which we call ‘actions’).

Using data gathered from this task, it is possible to see the exploitation-exploration trade-off in action. With each target people get 10 attempts to try to identify the right movement to make. Obviously some successful movements will be more efficient than others, because it is possible to hit the target after going all “round the houses” first, adding lots of extraneous movements and taking longer than needed. If you had a success like this you could repeat it exactly (‘exploit’), or try and cut out some of the extraneous movement and risk missing the target (‘explore’). Obviously this refinement of action through trial and error is of critical interest to anyone who cares about how we learn skilled movements.

I calculated an average performance score for the first 50% and second 50% of attempts (basically a measure of distance travelled before hitting the target – so lower scores mean better performance). I also calculated how variable these performance scores were in the first 50% and second 50%. Normally we would expect people who perform best in the first half of a test to perform best in the second half (depressingly people who start out ahead usually stay there!). But this analysis showed up something interesting: a strong correlation between variability in the first half and performance in the second half. You can see this in the graph

This shows that people who are most inconsistent when they start to learn perform best towards the end of learning. Usually inconsistency is a bad sign, so it is somewhat surprising that it predicts better performance later on. The obvious interpretation is in terms of the exploration-exploitation trade-off. The inconsistent people are trying out more things at the beginning, learning more about what works and what doesn’t. This provides them with the foundation to perform well later on. This pattern holds when comparing across individuals, but it also holds for comparing across trials (so for the same individual, their later performance is better for targets on which they are most inconsistent on early in learning).

You can read about this, and more, in our new paper, which is open-access over at PLoS One A novel task for the investigation of action acquisition.

academic psychology

New paper: A novel task for the investigation of action acquisition

Our new paper, A novel task for the investigation of action acquisition, has been published in PLoS One today. The paper describes a new paradigm we’ve been using to investigate how actions are learnt.

It’s a curious fact that although psychologists have thoroughly investigated how actions are valued (i.e. how you figure out how good or bad a thing is to do), and how actions are trained (i.e. shaped and refined over time), the same effort has not gone into investigating how a behaviour is first identified and stored as a part of our repertoire. We hope this task provides a useful tool for opening up this area for investigation.

As well as the basic description of the task, the paper also contains a section outlining how the form of learning the the task makes available for inspection is different from the forms of learning made available by other ‘action learning’ tasks (such as, for example, operant conditioning tasks). In addition to serving an under-investigated area of learning research, the task also has a number of practical benefits. It is scalable in difficulty, suitable for repeated measures designs (meaning you can do it again and again – it isn’t something you learn once and then can’t be tested on any more) as well being adaptable for different species (meaning you can test humans and non-human animals on the task).

The paper is based on work done as part of the EU robotics project I’m on (‘I’M-CLeVeR‘) and on Tom Walton’s PhD thesis, The Discovery of Novel Actions

idiocy intellectual self-defence

The Natures of Explanation

(Attention conservation notice: mostly me trying to work out what I mean. If you know, feel free to get in touch)

Explanation is not a zero-sum game. You can add additional explanations without negating existing explanations. The loss of life after the flooding of New Orleans was due to Hurricane Katrina. And it was due to climate change. And under-investment in the levees. And a history of social exclusion based on race and class. All these explanations are true, there is no explanatory exclusivity.

I am reading Bruno Latour’s “Science in Action” where he gives the best (only?) account I have seen of how any explanation can be countered or superseded by subsequent explanations. Scientists seek to settle claims – to generate “black boxes” of fact, in Latour’s terms – but the process of scientific debate sees a flux of competing explanations. An experiment by A said X. But two experiments by Y said not-X. But Y isn’t using the correct equipment, of course his experiments give the wrong results. But X’s equipment is biased to give the answer X, Y has to use non-standard equipment. But Z has shown not-X with A’s equipment for sub-case Z. And so on. Explanations seek to settle, but can always be weakened by subsequent explanations which qualify, reframe or negate. It is not just that subsequent claims diminish our confidence that X is the case, on some linear scale where 0>confidence>1. Instead, there is a fundamental uncertainty in the very metrics we are judging.

We seek to define or find (domains) where exclusivity applies. Responsibility and blame feels like a domain where exclusivity applies – almost by definition, because we want it to apply. If it was my fault it is not your fault. We want blame to sum to 1, so that even in complex cases we sort through the responsibility of all involved an apportion a limited amount of blame to each party.

Obviously, when non-exclusive explanations originating from science are used in the moral domain, it is natural for people to interpret them exclusively. If your brain or your environment made you commit a crime, it is not your fault. In a similar way – perhaps essentially similar – freedom of the will is often talked about as an exclusive property. Is your choice at the moment free OR is it pre-determined? This is a fundamental misconception, in my opinion.

You need a tolerance for ambiguity to deal in non-exclusive explanations. Usually we seek to find a restricted domain where we can argue over explanations which are, temporarily, exclusive. Is it nature or nurture? Is dyslexia caused by cerebellar dysfunction or magnocellular pathway dysfunction? For the non-restricted domain the ground can always shift underneath you. Someone can come along a redefine any element of what you are arguing about, including the tools of argument themselves.


Quote #285: Of Beauty

There is no excellent beauty that hath not some strangeness in the proportion

Francis Bacon (1561–1626), ‘Of Beauty‘.

psychology quotes

Psychology’s missing link

Affordance links perception to action, as it links a creature to its environment. It links both to cognition, because it relates to meaning. Mean­ing is in the world, as much as in the mind, because meaning involves the appropriateness of an organism’s actions to its surroundings

Eleanor Gibson, in Gibson, E. J. (1988). Exploratory behavior in the development of perceiving, acting, and the acquiring of knowledge. Annual review of psychology, 39(1), 1–42.


Links for March-February 2012

academic psychology sheffield

We’re hiring!

The Department of Psychology at the University of Sheffield is hiring! Due to recent departures and a forthcoming expansion we have 6 academic posts to fill, for lecturers, senior lecturers/readers and chairs. Perhaps you, or someone you know, is looking for a job or a change – here’s why you should apply to work with us:

The Department: One of the very best Psychology departments in the UK for research, consistently rated ‘excellent’ (i.e. the top score) in the Research Assessment Exercises over the last 20 years. In the last RAE the department ranked 6th in the UK in terms of Research Power (i.e., quality × quantity of research activity). We have a strong tradition of interdisciplinary research and you’d be joining at a great time to renew that tradition of cognitive science. We have smart and enthusiastic Undergraduate students, 80% of whom have AAA at a-level (ie the top grades). We have one of the largest number of postgraduate students for any UK psychology department, which includes taught masters courses (I teach on this one) and PhD students. The academic faculty are dedicated and collegiate, small enough in numbers to be friendly, large enough to be a resource for you in your research. We have one of the best staff-student ratios of any UK psychology department…All this, and you get me as a colleague

The University: Times Higher Education University of the Year 2011, and globally one of the best universities in the world. The University of Sheffield has academic departments covering all major disciplines and is a ‘research intensive University‘, meaning you wouldn’t spend all your time teaching.

The City of Sheffield. Ah, Sheffield! More parkland within the city limits than any other UK city. 7 trees for every person. The so called “largest village in England”, a city renowned for its friendliness, for its sporting links, creative industries and generally too many good things to list here. And it’s in the middle of the country, so you can get about easily – two hours from the capital, three from Bristol, four Edinburgh. And cheap – I live in a house which makes my London friends who can’t afford a flat sick with jealousy. I can walk to work, or round to friend’s houses. I’m talking quality of life here people.

So, please pass the word around that we’re looking for psychologists of all types to apply for these positions. If you want to get in touch I’m happy to talk informally to anyone who is thinking about applying. Not that I have any significant power over the hiring decision, but I’m happy to spill the beans over what we’re looking for and what the department is like. You can contact me by phone or email.

(In sad, but unrelated news, we lost our Professor of Development Psychology earlier this week. These job adverts are obviously quite separate from this sudden gap we have in Developmental Psychology and about which no plans have yet been made).

advertising politics psychology

Media Violence, Unconscious Imitation, and Freedom of Speech

I really enjoyed the ideas discussed in Susan Hurley’s 2006 article “Bypassing Conscious Control: Media Violence, Unconscious Imitation, and Freedom of Speech“. The basic argument is that if we realised that we tend to automatically and unconsciously absorb and imitate patterns of behaviour that we observe, then our views of freedom of expression would be quite different from what they are. Although the presentation of the empirical psychology is sophisticated, the language does tend to slip into conceding that there is a domain of unconscious, automatic influences on behaviour and a separate realm of conscious, deliberative, choice. This is a failure to recognise, in my opinion, that for all behaviour it is causation all the way down (or all the way through, perhaps). But this quibble aside, the article gives evidential and philosophical reasons for us to be more concerned than we appear to be about the mental environment our culture promotes.

I was sad to find out that we won’t be hearing any more from Prof Hurley: Obituary by Andy Clark.

Susan L. Hurley (2006). Bypassing Conscious Control: Media Violence, Unconscious Imitation, and Freedom of Speech. In S. Pockett, W. Banks & S. Gallagher (eds.), Does Consciousness Cause Behavior? MIT Press.

advertising psychology

What if an evil corporation knew all about you?

Facebook have announced their first share offer. There was a fairly nuanced discussion on the BBC’s Today programme, which contained the useful maxim: if the service is free then you are the product. We pour personal information about ourselves – our locations, likes, friends and activities – into Facebook and Facebook sells that bit of us to advertisers. John Humphrys managed a grumble about whether we could trust a corporation with all that personal information, but nobody in the discussion seems to be able to raise much by way of concrete reasons not to give Facebook that information about yourself, they just had vague worries. Elsewhere, Cory has talked about the privacy bargain we make with corporations, and the dangers of making that bargain unknowingly or carelessly, but I want to leave that aside for a moment. Imagine a world where everyone was aware of exactly what Facebook were doing – ie selling information about our desires to advertiser. In this case, the vague worry about Facebook crystalises around a psychological question – can we be manipulated by corporations that know our desires? Imagine, if you will, that Facebook is the equivalent of the malevolent demon of Cartesian philosophy, still absolutely evil in intent, but different in that it can only control you through precisely targeted marketing messages, not through direct control of yours senses. Would you still sign up for a Facebook account? Say the Facebook Demon finds out you like lemons. Lemon Products Inc advertise you Lemon Perfume, LemonTech advertise you a lemon squeezer and Just Lemons Inc. offer you 10% off the price of lemons in their stores. Is this a bad world? The answer is only yes if you believe in the power of advertisers to make us do things we don’t want.

politics quotes

a site of struggle for control of the conditions of knowledge production

Whether in schools or in other public spheres, public intellectuals must struggle to create the conditions that enable students and others to become cultural producers who can rewrite their own experiences and perceptions by engaging with various texts, ideological positions, and theories. They must construct pedagogical relations in which students learn from each other, learn to theorize rather than simply ingest theories, and begin to address how to decenter the authoritarian power of the classroom. Students must also be given the opportunity to challenge disciplinary borders, create pluralized spaces from which hybridised identities might emerge, take up critically the relationship between language and experience, and appropriate knowledge as part of a broader effort at self-definition and ethical responsibility. What I am suggesting here is that public intellectuals move away from the rigid, ideological parameters of the debate about the curriculum or canon. What is needed is a new language for discussing knowledge and authority and the possibility of giving the students a role in deciding what is taught and how it is taught under specific circumstances. The question is not merely, who speaks and under what conditions? It is also about how to see universities (and public schools) as important sites of struggle over what is taught and for control of the conditions of knowledge production itself.

Giroux, H. A. (1997). Pedagogy and the politics of hope: Theory, culture, and schooling: a critical reader. WestviewPress (Boulder, Colo.), p263.

Me psychology science

It isn’t simple to infer cognitive modules from behaviour

Previously I blogged about an experiment which used the time it takes people to make decisions to try and elucidate something about the underlying mechanisms of information processing (Stafford, Ingram & Gurney, 2011) . This post is about the companion paper to that experiment, reporting some computational modelling inspired by the experiment (Stafford & Gurney, 2011).

The experiment contained a surprising result, or at least a result that I claim should surprise some decision theorists. We has asked people to make a simple judgement – to name out loud the ink colour of a word stimulus, the famous Stroop Task (Stroop, 1935). We found that two factors which affected the decision time had independent effects – the size of the effect of each factors was not effected by the other factor. (The factors were the strength of the colour, in terms of how pale vs deep it was, and how the word was related to the colour, matching it, contradicting it or being irrelevant). This type of result is known as “additive factors” (because they add independently of each other. On a graph of results this looks like parallel lines).

There’s a long tradition in psychology of making an inference from this pattern of experimental results to saying something about the underlying information processing that must be going on. Known as the additive factors methodology (Donders, 1868–1869/1969; Sternberg, 1998), the logic is this: if we systematically vary two things about a decision and they have independent effects on response times, then the two things are operating on separate loci in the decision making architecture – thus proving that there are separate loci in the decision making architecture. Therefore, we can use experiments which measure only outcomes – the time it takes to respond – to ask questions about cognitive architecture; i.e. questions about how information is transformed and combined as it travels between input and output.

The problem with this approach is that it commits a logical fallacy. True separate information processing modules can produce additive factors in response data (A -> B), but that doesn’t mean that additive factors in response time data imply separate information processing modules (B -> A). My work involved taking a widely used model of information processing in the Stroop task (Cohen et al, 1990) and altering it so it contained discrete processing stages, or not. This allowed me to simulate response times in a situation where I knew for certain the architecture – because I’d built the information processing system. The result was surprising. Yes, a system of discrete stages could generate the pattern of data I’d observed experimentally and reported in Stafford, Ingram & Gurney (2011), but so could a single stage system in which all information was continuously processed in parallel, with no discrete information processing modules. Even stranger, both of these kind of systems could be made to produce either additive or non-additive factors without changing their underlying architecture.

The conclusion is straightforward. Although inferring different processing stages (or ‘modules’) from additive factors in data is a venerable tradition in psychology, and one that remains popular (Sternberg, 2011), it is a mistake. As Henson (2011) points out, there’s too much non-linearity in cognitive processing, so that you need additional constraints if you want to make inferences about cognitive modules.

Thanks to Jon Simons for spotting the Sternberg and Henson papers, and so inadvertantly promting this bit of research blogging


Cohen, J. D., Dunbar, K., and McClelland, J. L. (1990). On the control of automatic processes – a parallel distributed-processing account of the Stroop effect. Psychol. Rev. 97, 332–361.

Donders, F. (1868–1869/1969). “Over de snelheid van psychische processen. onderzoekingen gedann in het physiologish laboratorium der utrechtsche hoogeshool,” in Attention and Performance, Vol. II, ed. W. G. Koster (Amsterdam: North-Holland).

Henson, R. N. (2011). How to discover modules in mind and brain: The curse of nonlinearity, and blessing of neuroimaging. A comment on Sternberg (2011). Cognitive Neuropsychology, 28(3-4), 209-223. doi:10.1080/02643294.2011.561305

Stafford, T. and Gurney, K. N.(2011), Additive factors do not imply discrete processing stages: a worked example using models of the Stroop task, Frontiers in Psychology, 2:287.

Stafford, T., Ingram, L., and Gurney, K. N. (2011), Pieron’s Law holds during Stroop conflict: insights into the architecture of decision making, Cognitive Science 35, 1553–1566.

Sternberg, S. (1998). “Discovering mental processing stages: the method of additive factors,” in An Invitation to Cognitive Science: Methods, Models, and Conceptual Issues, 2nd Edn, eds D. Scarborough, and S. Sternberg (Cambridge, MA: MIT Press), 702–863.

Sternberg, S. (2011). Modular processes in mind and brain. Cognitive Neuropsychology, 28(3-4), 156-208. doi:10.1080/02643294.2011.557231

Stroop, J. (1935). Studies of interference in serial verbal reactions. J. Exp. Psychol. 18, 643–662.


A National Eccentricity Index

I’ve been wondering if it would be remotely possible to measure the amount of eccentricity in a culture. In particular, I’m wondering about the historical trend in number of people who are “characters” – ie the distinctly usual. Anecdotally, I’ve been told that 60 years ago there were more people who marched to the beat of a different drum, and it isn’t hard to imagine a story about the homogenising influence of modern and commercial culture. It also isn’t hard to imagine that all sorts of selection biases and preconceptions are at work, so that there really hasn’t been any change in this over recent history. So – could it be measured?

I was doing some research the other day, on what questions people ask about psychology. This tends to overlap, but not by much, with the questions that we as professional psychology researchers invesitgate. If you’re interested you can look for yourself:

Very common, it seems, is the question “Am I normal?” or “is this normal?”. Did people always ask this question, or is it particularly modern? If you do a google ngram search for the words “strange” and “normal” you get an interesting pattern:

More normal (in red), and less strange (in blue) over the last two centuries. They even appear inversely related at points – notice the damping of ‘strangeness’ around WWI and WWII and a surge in ‘normality’.

Me psychology science

An experimental test of ‘optimal’ decision making

I’ve had a pair of papers published recently and I thought I’d have a go at putting simply what the research reported in them shows.

The first is called ‘Pieron’s Law holds during Stroop conflict: insights into the architecture of decision making‘. It reports a variation on the famous Stroop task. The Stroop task involves naming the ink colour of various words, words which can themselves be the name of colours. So you find yourself looking at the word GREEN in red ink and your job is to say “red”. If the word matches the ink colour people respond faster and more accurately; if the word doesn’t match, they are slower and less accurate. What we did was vary the strength of the colour component of the stimilus – e.g. we used more and less intense red ‘ink’ (actually we presented the stimuli on a computer screen, so the ink was pixel values). There’s a well established relationship between stimulus strength and responding – the ‘Pieron’s Law’ of the title – showing how response speed decreases with increasing stimulus strength.

So our experiment simply took two well know psychological findings and combined them in a single experiment. The result is interesting because it can help us arbitrate between different theories of how decisions are made. One popular theory of decision making is that all the information relevant to the decision is optimally combined to produce the swiftest and most accuracte response (Bogacz, 2007). There’s lots of support for this theory, including evidence from looking at responses of humans making simple judgements, recordings from the brain cells of monkeys and deep connections to statistical theory. It’s without doubt that the brain can and does integrate information optimally in some circumstances. What is interesting to me is that this optimal information integration perspective is completely at odds with the most successful research programme in post-war psychology: the heuristics and biases approach. This body of evidence suggest that human decision making is very non-optimal, with all sorts of systemmatic errors creeping into the way people combine information to make a decision. The explanation for these errors is that we process information using heuristics, mental shortcuts which give a good answer most of the time and cut down on the amount of effort which have to expend in deciding (“do what you did last time” is probably the most common decision heuristic).

My experiment connects to these ideas because it asked people to make a simple judgement (the colour of the ink), like the experiments supporting an optimal information integration perspective on decision making, but the judgement requested was just marginally more complex because we manipulate both Stroop condition (whether the word and ink matched) and colour strength. If you are a straight-down-the-line optimal information decision theorists then you must believe that evidence about the decision based on the word is combined with evidence about the decision based on the colour to make a single ‘amount of evidence’ variable which drives the decision. In the paper I call this the ‘common metric’ hypothesis. The logic is a bit involved (see the paper), but a consequence of this hypothesis is that the size of the effect of the word condition should vary across the colour strength condition, and vice versa. In other words, you should see an interaction. Visually, the lines on the graph of results would be non-parallel.

Here’s what we found:

What you’re looking at is a graph of response times (the y-axis) for different colour strengths (the x-axis). The three lines are the three Stroop conditions: when the word matches the colour (‘congruent’), when it doesn’t match (‘conflict’) and when there is no word (‘control’). The result: there is no interaction between these two factors – the lines are parallel.

The implication is that you don’t need to move very far from simple perceptual decision making before human decision making starts to look non-optimal – or at least non optimal in the sense of combining information from different sources. This is important because of the widespread celebration of decision making as informationally optimal. Reconciling this research programme with the wider heuristics and biases approach is important work, and fits more generally with an honourable tradition in science of finding “boundary conditions” where one way the world works gives way to another way.

Coming up next: Infering from behavioural results to underlying cognitive architecture – its not as simple as we were told (Stafford & Gurney, 2011).


Bogacz, R. (2007). Optimal decision-making theories: linking neurobiology with behaviour. Trends in Cognitive Sciences, 11(3), 118–125.

Stafford, T., Ingram, L. and Gurney, K.N.(2011), Pieron’s Law holds during Stroop conflict: insights into the architecture of decision making, Cognitive Science 35, 1553–1566.

Tom Stafford and Kevin N. Gurney (2011), Additive factors do not imply discrete processing stages: a worked example using models of the Stroop task, Frontiers in Psychology, 2:287.

events Me

Psychology in the Pub, Sheffield

(Local news warning: just details of a talk I’m giving)

Psychology in the Pub is a Sheffield event which happens in the Showroom Cinema Bar. I’m giving a talk there on the 15th of March and I’ve just written the blurb. Here it is for your enjoyment

Thinking Meat: Understanding brain and mind

You’re brain weighs the same as half a brick and has the consistency of warm butter. Yet such a mundane object allows you to have every thought you’ve ever had, every feeling, dream or hope. This talk will be an introduction to what I view as the central puzzle of psychology: how the brain creates the mind. I’ll discuss fundamental insights from the study of perception and action and suggest how these provide important clues for understanding all of human psychology. The talk will feature: Lego Robots! ‘Subliminal messages’! Britney Spears! Pirates! And a no-holds-bared personal revelation from the speaker

The content will be similar to the talk I gave in Manchester recently, which you can hear here


Quote #282

But I don’t want comfort. I want God, I want poetry, I want real danger, I want freedom, I want goodness. I want sin.

The Savage to Mustapha Mond, in Aldous Huxley’s Brave New World (1932), p187


Quote #281

Do not seek to follow in the footsteps of the wise. Seek what they sought.

Matsuo Basho (attrib.)


Quote #280: Butterfly dreams

Once upon a time, I, Chuang Chou, dreamt I was a butterfly, fluttering hither and thither, to all intents and purposes a butterfly. I was conscious only of my happiness as a butterfly, unaware that I was Chou. Soon I awaked, and there I was, veritably myself again. Now I do not know whether I was then a man dreaming I was a butterfly, or whether I am now a butterfly, dreaming I am a man. Between a man and a butterfly there is necessarily a distinction. The transition is called the transformation of material things.

Master Chuang (c. 369 BC – c. 286 BC)


Control your dreams (ebook)

Anyone can learn to have lucid dreams, and this ebook tells you how. Lucid dreams are those dreams where you become aware you are dreaming, and can even begin to control the reality of the dream. Adventure, problem-solving and consequence-free indulgence await! And for those interested in the mind, lucid dreams are a great place to explore the nature of their own consciousness. The ebook is written as a sort of travel guide, telling you what you need to take on your journey and what to expect when you start to lucid dream. It finishes off with a quick review of the scientific literature on lucid dreaming and links and references for further reading if you want to continue your exploration of lucid dreaming.

I wrote this with friend, and lucid dreamer, Cat Bardsley. My wife Harriet Cameron provided some beautiful illustrations which you can find throughout the book (and on the cover you can see here). The book is Creative Commons licensed so you can copy it and share it as you will, and even modify and improve (as long as you keep the CC licensing). It’s available on smashwords on a pay-what-you-want-basis (and that includes nothing, so it is yours for free if you’d like).

“Control your dreams” is my second self-published ebook. You can also get “Explore your blindspot” from smashwords (which is completely free, and also CC licensed). The wonderful folk at 40k books published my essay The Narrative Escape last year (and after doing all the formatting and admin associated with these two new ebooks I am more and more in awe of what they did).

Sweet Dreams!

(Cross-posted at


G. A. Cohen’s “Freedom and Money” (2001)

In which Cohen argues that lack of money is a lack of political freedom, and that the issue of private property (which is axiomatic to libertarians) cannot be determined independently of issues of political freedom. In other words, you can’t reasonably set aside the issue of distribution of property (i.e. wealth) from your consideration of freedom. This pervasive confusion, Cohen argues, arises because of a misperception of the nature of money, which appears as a real thing, like rocks or even like physical strength, but is actually “social power in the form of a thing” (Marx).

Anyway, it is a great read, lucid and mind expanding, and a great example of political philosophy . I can’t find a journal reference for it, but it is – apparently – reprinted in On the Currency of Egalitarian Justice, and Other Essays in Political Philosophy (2011)

Link to PDF (thanks Josie!)


links for December 2012


Quote #279

Lord, we know what we are, but not what we may be

Ophelia, in Hamlet,Act 4, Scene 5, by William Shakespeare (1599-1602 ish)

intellectual self-defence quotes

The Principles of Newspeak

The purpose of Newspeak was not only to provide a medium of expression for the world-view and mental habits proper to the devotees of IngSoc, but to make all other modes of thought impossible. It was intended that when Newspeak had been adopted once and for all and Oldspeak forgotten, a heretical thought — that is, a thought diverging from the principles of IngSoc — should be literally unthinkable, at least so far as thought is dependent on words. Its vocabulary was so constructed as to give exact and often very subtle expression to every meaning that a Party member could properly wish to express, while excluding all other meaning and also the possibility of arriving at them by indirect methods.

From the foregoing account it will be seen that in Newspeak the expression of unorthodox opinions, above a very low level, was well-nigh impossible. It was of course possible to utter heresies of a very crude kind, a species of blasphemy. It would have been possible, for example, to say Big Brother is ungood. But this statement, which to an orthodox ear merely conveyed a self-evident absurdity, could not have been sustained by reasoned argument, because the necessary words were not available. Ideas inimical to Ingsoc could only be entertained in a vague wordless form, and could only be named in very broad terms which lumped together and condemned whole groups of heresies without defining them in doing so.

George Orwell, ‘The Principles of Newspeak’, the appendix to his ‘1984’ (1949)