We're all familiar with false popular memes that spread faster than they can be stomped out: You only use 10% of your brain. Al Gore said he invented the internet. Perhaps it doesn't surprise you that some memes in popular culture can't be killed. But does the same thing happen in science?
Most of you have probably heard of Broca's aphasia and Wernicke's aphasia. Every textbook and every college course on language and the brain describes the connection between damage to these areas, and the speech deficits named after them.
Also, both are probably wrong. Both areas were mistakenly associated with their aphasias because they are near or surrounded by other areas which, when damaged, cause the aphasias. Yet our schools continue teaching the traditional, erroneous story; including a lecture in 9.14 at MIT given in 2005. Both the Wikipedia entry on Wernicke's aphasia and the Wikipedia entry on Broca's aphasia are still in error; the Wikipedia entry on Wernicke's area has got it straight.
Is it because this information is considered unimportant? Hardly; it's probably the only functional association you will find in every course and every book on the brain.
Is it because the information is too new to have penetrated the field? No; see the dates on the references below.
In spite of this failure in education, are the experts thoroughly familiar with this information? Possibly not; this 2006 paper on Broca's area by a renowned expert does not mention it. (In its defense, it references many other studies in which damage to Broca's area is associated with language deficits.)
So:
- Am I wrong, and the evidence still implicates Broca's area and Wernicke's area in their aphasias above other areas?
- If I'm right, why can't the new understanding displace the old understanding?
- Is this a general failure in the way we do science? Can you think of other examples where an important discovery can't penetrate its field?
References
Bogen JE, Bogen GM (1976). Wernicke's region—Where is it? Ann. N. Y. Acad. Sci. 280: 834–43.
Dronkers, N. F., Shapiro, J. K., Redfern, B., & Knight, R. T. (1992). The role of Broca’s area in Broca’s aphasia.
Journal of Clinical and Experimental Neuropsychology, 14, 52–53.
Dronkers NF., Redfern B B., Knight R T. (2000). The neural architecture of language disorders. in Bizzi, Emilio; Gazzaniga, Michael S.. The New cognitive neurosciences (2nd ed.). Cambridge, Mass: MIT Press. pp. 949–58.
Dronkers et al. (2004). Lesion analysis of the brain areas involved in language comprehension. Cognition 92: 145-177.
Mohr, J. P. (1976). Broca’s area and Broca’s aphasia. In H. Whitaker, Studies in neurolinguistics, New York: Academic Press.
1- I can't remember anybody stating that "global warming has a serious chance of destroying the world". The world is a pretty big ball of iron. I doubt even a 10K warming would have much of an impact on it, and I don't think anybody said it would - not even Al Gore.
2- I can remember many people saying that "man-made global warming has a serious chance of causing large disruption and suffering to extant human societies", or something to that effect.
3- If I try to apply "reference class forecasting" to this subject, my suggested reference class is "quantitative predictions consistently supported by a large majority of scientists, disputed by a handful of specialists and a sizeable number of non-specialists/non-scientists".
4- More generally, reference class forecasting doesn't seem to help much in stomping out bias, since biases affect the choice and delineation of which reference classes we use anyway.
Well, I do recall a scientist using explicit "save the word"/"destroy the world" rhetoric. Of course this was rhetoric, not a scientific claim. A lot of non-scientist environmentalists do seem to think that global warming threatens the whole biosphere, though that seems very implausible based on what I know.