Can Cognitive Neuroscience Tell Us Anything About the Mind?
Cognitive neuroscience - essentially brain scanning - has become all the rage in psychology and related fields. Given the headlong rush by, well, practically everyone, into cognitive neuroscience I still entertain a quaintly unfashionable stance: I'm sceptical. My scepticism is not total though, many cognitive neuroscientists claim that there are many exciting findings to come. They're probably right, but while neuroimaging can certainly tell us much about the brain, there's reason to believe it hasn't told us much about the mind. To understand what I mean by this we need to go back to basics by asking what research is for.
"Does cognitive neuroscience really have the power to distinguish between psychological theories?"Like all scientists, psychologists are continually knocking out new theories to explain the way we think and behave. One of the most important functions of research is its ability to differentiate between two theories. If research doesn't at least provide a clue one way or the other then theoretically, and so practically, it's a waste of time. Does cognitive neuroscience really have the power to distinguish between psychological theories? Is it any use to a cognitive psychologist?
A critic's view
Max Coltheart is Professor of Psychology at Macquarie University in Australia and in a recent journal article he wonders whether cognitive neuroscience has really told us anything useful about the mind so far (Coltheart, 2006). It's important to realise that his emphasis is on the mind, as in cognitive processes, as distinct from the brain, as in physiological processes.
"Neuroscience's strength is in physiological processes..."There's no doubt the mind's cognitive processes are a function of the brain's physiological activity but these two things are nevertheless (currently) separate questions. Cognitive neuroscience's strength is in physiological processes, and as imaging technology improves, so will the importance of its findings in this area. But, again, why should a psychologist care that much which part of the brain lights up in a scanner, if the mind's functioning is still so far removed from our understanding of its physiology?
An example
All this can be difficult to grasp in abstract. Take one of Coltheart's examples. Suppose you're a psychologist interested in how people work out what other people are going to do. Their intentions. Suppose there are only two competing theories that you've got to choose between:
- 'Simulation theory': I literally run a crude simulation of your mental state in my own mind. From this I try and work out what you're going to do next.
- 'Theory theory': I create a theory about you, then try to work out what you're going to do from that.
"...evidence from cognitive neuroscience fails to distinguish between theories."This is just two theories and one study - not exactly a scathing criticism of the whole of cognitive neuroscience. But Coltheart does run through four other examples where evidence from cognitive neuroscience fails to distinguish between theories. Again, remember that we're talking about relatively high level psychological theories here, not low-level physiological processes.
Coltheart goes on to pull quotes from a range of people who argue that, in principle, neuroimaging is useless for psychological theory and understanding of the mind. Here's a good computing metaphor:
"No amount of knowledge about the hardware of a computer will tell you anything serious about the nature of the software that the computer runs. In the same way, no facts about the activity of the brain could be used to confirm or refute some information-processing model of cognition." (Coltheart, 2004, p.22)I personally don't know enough about cognitive neuroscience to argue whether or not this statement is true, but it certainly has intuitive appeal. Considering the enormous quantity of money going into cognitive neuroscience right now, it seems unlikely this would be a majority view amongst psychologists. Not that scientist are slaves to money, of course...Ahem...
What's your view?
There's precious little discussion of Coltheart's criticisms in the blogosphere and there's plenty of good neuroscience blogs around. Let me know what you think, leave a comment below.
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ReferencesColtheart, M. (2004) Brain imaging, connectionism and cognitive neuropsychology. Cognitive Neuropsychology, 2, 21-25.
Coltheart, M. (2006). What has functional neuroimaging told us about the mind (so far)? Cortex, 42(3), 323-31.
Ramnani, N., & Miall, R. C. (2004). A circuit in the human brain for predicting the actions of others. Nature Neuroscience, 7, 85-90.
Labels: Neuroscience
30 comments
Hi Jeremy,
I really enjoy your posts and I've been a subscriber of your feed for a few weeks now. However, it really bugs me that from my thirty-something feeds, yours is the only one that doesn't display the whole post. Ususally, I only get the first paragraph. Can you change it so that we can get the whole "package" through RSS? Thanks for your insightful posts and best!
Hey, thanks for pointing out the Coltheart paper. I don't read Cortex, so I might not have noticed it otherwise. First, I think you should be careful when you use the term "neuroscience" to refer largely (entirely?) to cognitive neuroscience, and neuroimaging in particular. Other areas of neuroscience, including neuropsychology that comes close to (if it doesn't qualify as) cognitive neuroscience, have taught us things. And the double dissociation method can be very powerful in testing theory.
That said, I mostly agree with the critique of neuroimagining, and I've said so many times publicly and privately. In addition to the problems with neuroimaging methods, especially the subtraction method, any imaging study will be so reliant on theory (for determining what areas to look at, and for interpreting differences in activation), that it's hard to know what it tells you. And no one has really developed an evidence-based theory of what differences in activation mean anyway.
Honestly, I'm not sure that imaging will ever tell us much. Imaging requires a commitment to a strong belief in that the localization of functions in the brain is universal. And while that may be true at some level (vision utilizes the same cortices across individuals), it may very well not be true at the level at which imaging operates.
Oh, and one thing I dislike about Coltheart's critique: his very old-school functionalism, in which he treats cognition (software) as entirely amodal. It's the strong AI belief that you can take any cognitive program and implement it in any hardware. That's one hell of a philosophical assumption.
Chris, you're welcome. And thanks for reminding me about the term neuroscience. I meant cog-neuro but I forgot to write the cog! I've changed that now.
Also happy to hear from a fellow sceptic.
Any supporters of cog-neuro out there? I've read that cognitive neuroscientist say when they've got enough studies they'll be able to tell us something useful. They argue that it's a matter of steadily accumulating data.
What exactly do you mean by "the mind"? Do you have any genuine evidence that such an entity exists? I understand what the term means in popular parlance, but is it actually meaningful in any concrete or scientific sense? Why should neuroscientists be concerned about competing theories about a phenomenon that may be merely lingusitic? I have no brief for or against cognitive neuroscience, but I am skeptical of claims about the existence of a "mind" that's separate from the brain.
Greg, thanks for your comment. I'm certainly not suggesting the 'mind' is separate in any physical or philosophical sense from the brain. To rely on that well-worn quote: "The mind is what the brain does." Unfortunately there's this huge gap between our knowledge of the brain's physiological functions and it's high-level operations, namely consciousness.
An example: one of the most important functions of the mind is memory. Psychologists have been studying this for ages and are pretty sure it exists (in most people).
This article is questioning what a cognitive neuroscientist can possibly tell you about memory. What can you understand about memory other than which parts of the brain are more active in certain situations? Does this low-level information lead to any high-level conclusions about how memory works? Can you distinguish between, for example, two theories of how memory operates?
Thank you for your clarification! I actually like your blog very much and have found much to ponder in it.
You're welcome Greg, I'm glad you enjoy it.
Also, to the very first commenter on this post 'Anonymous', I'll consider this, but I know many other feeds work in a similar way to mine.
For one thing you miss out on the comments if you don't come to the site. I know you can still comment by clicking through from your feed reader but I think it encourages more participation this way.
Jeremy,
Much work has been done learning how the brain works at the (nuts-and-bolts) level of neurons, and hundreds of years have been spent formally studying the brain from the (finished-product) level of behavior and understanding. I can't help but wonder if cog-neuro is an important first step in bridging the gap between the two. Although it may, by itself, teach us very little about the brain, it may give us important clues such as where and how to study the different parts of the brain.
Thoughts?
I would like to take issue with Coltheart's comparison with knowledge of computer hardware and the uses of functional imaging. In his summary you reproduce (unfortunately I can't get access to the full paper online, and admit making a critique based on a single paragraph is rather shaky ground), the position put forward seems to me to be an apples and oranges comparison: some (computer) hardware in the "off" state and the brain in a snapshot of its "on" state.
It is clear that simple knowledge of the hardware would provide no knowledge of the software running upon the machine. Were one to take snapshots of a computer's running states over time, however, it would be possible to build up a picture of what the computer is doing easily -- all the information you need is there, both the data and the program is stored in the computer's "on" snapshots, and you would be able to see how these progress. I would posit that this time-based snapshot of the "on" state is more similar to functional imaging. The brain, of course, may not have all its functions "on show" in the same way as a computer (which seems to be what you imply cognitive neuroscientists may expect).
As described by Coltheart's paragraph, knowledge of the computer's hardware is more analogous to expecting to discover the brain's functioning purely by dissecting a dead and inactive brain. Which I expect is impossible.
Functional imaging is great for finding brain regions that are sufficient for a particular phenomenon. However, to know it is necessary requires the out-of-fashion lesion method.
It's a pity, but there does seem to be a separation occuring in these methods. Fellows had an article a while back showing how the imaging literature is pretty much ignoring the lesion literature, wheras the lesion literature makes use of the imaging literature.
To know a particular region is necessary can be shown using lesion methods. Both imaging and lesion methods have weaknesses, if they work together, we can make much stronger inferences.
We need a more integrative approach.
Anonymous #2, you're talking about bridging the gap between the neurobiology and psychology. Yes, I think you've put your finger on why, intuitively, people feel cognitive neuroscience is/will be useful.
Mike, good point. But I still think Coltheart has a strong argument, as Chris says in an earlier comment: how do you know what activation in a particular part of the brain means? This question also speaks to what anonymous #2 is saying above. The temptation is to see cog-neuro as bridging the gap, but what evidence is there of any bridging going on?
Anonymous #3, yes and the great thing about lesioning studies is you have much stronger evidence that a particular part of the brain is really involved in a whatever function you're examining. Integration is certainly the way forward. I'm constantly amazed in all areas of psychology why there isn't more integration. Or is that like saying: why can't we just all stop fighting, be nice to each other and live in peace? It's not human nature.
There are at least two questions being asked here:
What does imaging tell us about the brain? (see Chris' comments)
What does the brain tell us about the mind?
It should be noted that the field of cognitive neuroscience is interested in both questions, and progressively takes an integrative methodological approach in which I believe brain imaging may have import. That said it is not a minority opinion that 'imaging for the sake of imaging' is a waste of time, and more generally that the 'where' question may be turn out to be largely disinteresting. In the history of science, this kind of machine driven fascination is nothing new.
The second question is certainly interesting, and the numerous attempts to progress our understanding in this regard can be traced from Sherrington's conception of 'the enchanted loom' to Fuster's most recent efforts ('Cortex and Mind' 2003).
Fuster sees a desparate need to identify linearity between the cortical and mental. The crux of Coltheart's argument would seem to be that no such linearity exists, but as Chris points out, his overt functionalism suggests that he really hasn't thought about it that much. Fuster is far less sceptical, and his favoured approach (a PDP network model of cortical representation as physiological - psychological interim, termed the 'cognit') makes me optimistic too.
But finally let's not forget that the study of the mind is similarly the prey of the sceptics - it is no easier to go from mind to brain. Therefore it is reasonable to assume that the growth of cognitive neuroscience and funding thereof is due to a growing (economical) interest in the brain, and a faltering interest in the mind, which at its very crudest can appear to be no more than a arbitarily structured taxonomy of competences.
Sherrington summed up the problem at least 70 years ago:
"Human cognition may like the winged horse take at times its flights toward the stars and forget Earth."
Thanks for your thoughful comment Jonathan. I think that's a useful split you point out between the threads of this discussion.
Overall, though, the discussion in the comments here is quite philosophical. I'm still waiting for some hard evidence that cog-neuro is worth all the attention. For example, if I were to try and write a top ten list of cog-neuro studies as I've done for psychology in general, what would be on there?
Jeremy,
I must confess that I have a hard time understanding the current hostility towards neuroimaging. (Disclaimer: I work with fMRI myself.) Certainly, people have made exaggerated claims about what we can learn about the brain using imaging. But in the end, neuroimaging is just a method - or actually: a number of different methods - for monitoring brain activity. It can be used to learn something about how the brain works, just as single cell recording, neuropsychological testing, genetic knock-out studies, etc., etc. can. I also think it is worth noting that neuroimaging is not only used to locate brain activity. It is also possible to monitor cellular and molecular processes through the use of neuroimaging methods. Indeed, reserachers have recently used MRI to monitor gene expression [1]!
I understand that the question posed by Coltheart is whether neuroiamging can tell us anything about cognitive functions. However, I think Coltheart sets an absolutely impossible standard for answering this question in the affirmative. Why should the criteria be that we are able to decide between (pre-existing) cognitive theories? In my view it is clearly possible to say that neuroimaging has contributed to the understanding of cognitive function, even this criteria is not met.
Having said that, I recently spoke to Peter Hagoort, a prominent psycholinguist, at a conference, and he actually told me that he thinks the results coming out of the last 15 years of EEG, PET, and fMRI language studies rather convincingly shows that Chomsky's specific theory cannot be true! So there...
[1] C. Liu et al. (2007): Imaging cerebral gene transcripts in live animals. J. Neuroscience 27: 713-722.
Martin, thanks very much for your comment, very interesting reading.
I'm interested in what you say about current hostility to neuroimaging. Do you find there's a lot?
On the point you make about Coltheart's impossibly high standards, I think there's some truth to what you say. On the other hand, I think you might be setting the bar too low, by just looking for some (any?) contribution.
Thanks for the language example. There's actually a few companion pieces in that issue of Cortex arguing for what neuroscience has contributed. Perhaps I'll write those up in a future post so we can look more closely at its achievements.
Hi,
I do not know a lot about neuroscience, but as a computer engineer I could not help noting the wrong analogy. One can get a lot of information about the software by studying the hardware. All programs are finally translated into a series of zeros and ones and by looking into these machine instructions, one can infer a lot about the software.
It is a very common practice in cracking/ reverse engineering to study the machine instructions and memory contents in order to get insite into a software without source code.
And in reality, your hardware and software are not very different, there are microcircuits that do the same job as a software and they all work on the same mathematical principles. Software is just more flexible ( easier to change ) than hardware.
I do not see any logical principle preventing people from understanding mind by studying the brain, though practically it may be impossible ( which I hope might someday be overcome by new technologies ).
Thanks and regards,
RayS
Cognitive neuroscience is clearly not just about studying the brain-- else there would be no need for the "cognitive" part. On the other hand, I don't think it will ever be a stand-alone tool to study the mind. Any conclusions about the operation of the mind hinted at by brain activations or whatever must ultimately be validated by more traditional kinds of behavioral data to gain real traction.
I think the relevance of cognitive neuroscience is not in studying the mind or brain separately, but in studying the relationship between the two. If the mind is what the brain does, cognitive neuroscience studies how the brain does the mind. It's shedding light on the age old mind body problem.
Of course, in addition to the philosophical insights, there are straightforward practical applications. Knowing how the brain does the mind allows one to treat the impaired mind by means of changing something about the brain.
The analogy of brain/mind hardware/software is naive. In fact, sufficient knowledge of computer hardware could but upper limits on the software's performance or size, for example, among other things.
The analogy could be better drawn if I were to compare the ability to take measurements of the activity of the computer while it is in operation to fMRI. In that case it might indeed be possible, given sufficient knowledge of the constituent parts, to deduce the code the machine is using and understand quite a bit about not only what kind of software is running, but if it similar to other kinds running on different machine.
At the very least neuroimaging, electrophysiology, MEG etc give us a chance to fill in some of those squares the cognitive scientists (such as myself) like to draw.
Thanks for your comments Rays and the two anonymouses. Following on from what you're saying I thought you might find this post at MindHacks of interest about Dr Brad Pasanek who has created a database of metaphors of the mind.
I just like to add a quick comment regarding the perceived hostility towards fMRI approaches both from neuroscientists and from cognitive scientists.
I do not think that there is something fundamentally wrong with fMRI and clearly some results are important (if neither for neuroscience nor for cognitive science at least for medicine). However I guess the reason why many people feel deeply uncomfortable about fMRI approaches is that a technique that has neither had great impact on our understanding of the brain nor had great impact on our understanding of the mind all of a sudden is the most successful approach in terms of funding and visibility.
Clearly fMRI promises new progress in a range of fields. However, there are fundamental dangers. fMRI tends to encourage a way of thinking about the brain as a set of little specialized processors connected to one another. Because fMRi can only visualize localization of function it makes many people believe that the brain is radically localized, an idea that is not supported by electrophysiology. The kind of theory that many scientists derive from fMRI may be neither helpful for neuroscience nor for cognitive science.
Thanks anonymous, I think there's a lot of truth in what you say.
I wouldn't dare disagree with an eminent psychologist but I think Coldheart is wrong. You can tell a great deal about the software on a computer from examining the hardware. Hardware determines the characteristics of the software - apple hardware won't run microsoft software (for example). So by determining that the harware is apple, you can also determine that the software is not microsoft.
In the same way the physical characteristics of the neural network constrain and define what can and cannot be done by the brain (e.g telepathy and telekenisis are impossible because the brain is insufficently sensitive to magnetism).
I simply dont't beleive that the brain and the mind are 2 separate entities. The "mind" is just what the brain does, it's our subjective experience of a particular pattern of neural activation at a particular point in time. Many parts of the body are not fully understood - yet medicine does not see the need to invent metaphysical constructs to fill the knowledge gaps - why does psychology ?
Matt, like earlier commenters, I think we might have pushed this software/hardware metaphor further than it really goes. Also I don't think anyone is suggesting brain and mind are separate. But, as you say there does seem to be a temptation to invent something to bridge the gap between the two.
---------
For example, if I were to try and write a top ten list of cog-neuro studies as I've done for psychology in general, what would be on there?-----
For example, kandel (nobel prize 2000)
for discoveries concerning signal transduction in the nervous system.
I know he didnot use fMRI but he is a neuro scientist.
Author of:
Principles of Neural Science, 4th Edition
I'm no neuroscientist, but you could call me an interested student of this stuff as it applies to my coaching practice.
I'm currently reading Dan Goleman's "Social Intelligence", which as far as I've read is trying to make the information we get from imaging useful, maybe you've already read it, if not it may be worth checking out.
Other thing I thought of is this video of a TED speech by V.S. Ramachandran that also is trying to make the connection between physiology and psychology. Here's the web address: http://www.spring.org.uk/2007/10/ramachandran -on-capgras-syndrome.php
Thanks Hatsch and Thomas.
I'm an italian student, I'm graduated in experimental psychology. I read all your comments.
But there is an experimental technique, TMS (i.e. transcranial magnetic stimulation) that allows to understand both the brain and the mind. It isn't a brian imaging technique but It can "read" the brian functions. The TMS create a magnetic field that modifies the electric field of brian iterferring with the brian activity. If we stimulate a particular area involving in a particular task we observe an interference in that task. So we can acquire information about localization of cognitive functions. But also...
we can analyze the chronometry of mind. With a single-pulse TMS, we can give a single stimulation in a fixed temporal window. If the process occurs in that time it would be modified, if it occurs before or after the stimulation, it would be unmodified. So we can know when a cognitive process is involved.
If you are interest, I suggest a paper: "Studies in cognition: the problem solved and created by transcranial magnetic stimulation" by E.M. Robertson et al.
P.S. I'm sorry for my bad english
Here's the problem as I see it.... using current cognitive neuroscience techniques to understand brain-behavior relationships is currently like trying to understand the functioning of a car's motor by measuring the heat patterns on the hood of the car. We can tell when it's working harder (and which areas show the biggest changes), but that's a far cry from truly understanding motor function.
Claim are often overstated and the work has been too exploratory for too long. Unfortunately, trying to understand an engine while it's working is darn near impossible.
It's hard for me to foresee the future of this work until the technology proceeds much farther. However, precise measurement may simply highlight another problem - no two brains work exactly alike.
Cheers,
Mike
Mike, I couldn't agree more!
For the "pro neuroimaging point of view" check out a recent article by Jason Mitchell that outlines areas in which neuroimaging has contributed to research in social cognition:
http://www.blackwell-synergy.com/doi/abs/10.1111/j.1467-8721.2008.00564.x
A few other places where I think neuroimaging can help understand things that previous psych work has not:
-How do implicit and explicit attitude interact to result in our ultimate evaluations/ attitudes/ behaviors? See Cunningham & Zelazo (2007) for an overview of one theory that integrates past work in psych, cognitive science, and insights provided from neuroimaging.
-On a related point, how do people control race bias? See work by Phelps and colleagues.
-Distinctions between internal and external focus: see review article by Lieberman (2007) on core processes in social cognitive neuroscience.