I was discussing possible PhD labs with a student, and she said, "I was thinking about some fMRI labs, but..."
"Yeah, that's not neuroscience," I said.
I've long held this belief, and when I mention it to other neuroscientists, they generally agree. But I've not heard it vocalized (birdsong term!) publicly, out of politeness or politics (fMRI gets a lot of funding and publicity, so badmouthing it looks envious). Today I'm going to lay out what I think the difference is between cognitive science and neuroscience, and why the distinction has blurred.
What irks me most is the application of the term "cognitive neuroscience" to research that uses techniques like fMRI or EEG. In my mind, there is a clear delineation between cognitive science and neuroscience, due to differences of technique and perspective. If I could summarize the difference in one sentence I'd say, "if it ain't describing neurons, it ain't neuroscience."
The difference between neuroscience and cognitive science is most clear on the technical side. Neuroscience techniques focus, naturally, on individual neurons (patch, imaging, extracellular recording) or groups of neurons (voltage sensitive dyes, wide field imaging, immunoblotting). Cognitive techniques, on the other hand, look at areas of the brain as a whole, like EEG, fMRI, or DTI.
The techniques one uses in turn determine the types of questions one can answer.* In broad terms, neuroscience techniques have specific measures, and so the questions neuroscientists ask are concerned with concrete, well defined inputs and outputs. How does this neuron represent that stimulus? How do two signaling molecules interact? We want to break the brain down like a car, so we can better understand it.
* Intuitively, one might think that the questions drive the technical split, and thus the difference between neuroscience and cognitive science. Certainly, individuals (and labs) are interested in questions, and acquire the techniques to answer those questions. Yet, questions can be answered on multiple levels. For example, if you're interested in sensory perception, your techniques can range from biophysics to neuroscience to psychophysics. You can explore the question via neuroscience or cognitive science.
In the end, I think identity is driving this distinction. I feel kinship with people who perform similar techniques, even in different systems. I feel like I could walk into any neuroscience lab, and start producing data within a few months, while it would take longer to become competent in a psych lab. So when I think of cognitive neuroscientists, I think of not-me, and would like clear labels to distinguish us.
Cognitive science's techniques, on the other hand, are more imprecise, but have much more interesting model organisms: humans and primates. Thus, they leverage their animal model by asking more slippery questions** regarding topics like consciousness, decision making, or emotion, which neuroscience is unable to answer at the moment. They move beyond treating the brain like a black box as in psychology, and do the best they can with the tools available.
** Dale Purves, the former chair of Duke Neurobiology, switched from cellular neuroscience to cognitive science late in his career. Whenever he went to talks, he would quasi-troll people by asking simple questions like, "What is a decision?", and arguing with their answer).
Then there is, of course, the overlapping field of cognitive neuroscience (I love Wikipedia's attribution of the term to two guys in a cab). While others may think fMRI is cognitive neuroscience, in my mind, the only cognitive neuroscientists are those who attempt to address those fuzzy cognitive questions by sticking electrodes in primates and humans
Why the confusion
So why have cognitive scientists coopted the prefix "neuro?" It's a pure status play.
Cognitive science is a small step removed from psychology, and psychology, despite decades of normalization, is still a dirty word to the public. When people think psychology, they think clinical psychology, people laying on couches, and the bizarre, foundational theories of Freud. They don't think rigorous science, they think feelings.
What the public doesn't realize is that most psychology, and most research psychology, is non-clinical, and encompasses cognitive, developmental, and other psychologies. And that non-clinical psychology has undergone tremendous improvement over the last few decades (say, post-Skinner), and employs all the standard tools of science like control groups, replication, etc. I enjoy me a good pop-psychology book.
So, given the low status of psychology, and neuroscience's higher relative status (neuro is an obscure Greek prefix, always a good sign), cognitive scientists doing fMRI rebranded the field "cognitive neuroscience." And lo, the NIH money flowed.
You can see other fields doing this as well, like neuroeconomics. There are some true neuroeconomists doing risk/reward research in primates, but most of it is just rebranded experimental economics.
To recapitulate: cognitive scientists and neuroscientists use different techniques to answer different questions. But cognitive scientists are wary of being mistaken for psychologists, and so coopted the term "neuro." It's mostly just a matter of semantics, but I thought fMRI people should know, when they call themselves neuroscientists, we ain't buying it.
(And I should reiterate here that I like psychology and cognitive science. They study the brain through a different lens, which is important. I just take issue with the misapplication of "neuroscience.")