Tuesday, 24 June 2008

Is the brain irrelevant to psychology?

Cognitive neuroscience explores how our mental faculties emerge from, and are organised in, the slimy tissue of our brains, and it's currently a thriving field. But some critics argue it's a dead-end, that biology is irrelevant to psychological accounts of how our minds work. In the words of philosopher Jerry Fodor, "If the mind happens in space at all, it happens somewhere north of the neck. What exactly turns on knowing how far north?"

Now, writing in a special journal issue on the interface between psychology and neuroscience, language expert Peter Hagoort has hit back, arguing that knowing something about the biology of cognition can help to shape psychological models.

Hagoort cites two key examples to support his claims. A little background is required.

When we encounter an unexpected word in a sentence ("He spread his warm bread with SOCKS."), a negative spike in electrical activity recorded from the surface of the scalp is detectable 400ms later and is thought to reflect the extra brain processing required for the surprise word.

Meanwhile, when we encounter a grammatical anomaly (e.g. "The boys kissES the girls") - there is a positive, more posterior, spike of activity, 600ms afterwards. This latter effect is observed even with nonsense sentences that violate grammatical rules, thus showing that the spike is independent from the processing of meaning.

Taken together, Hagoort says these findings have implications for psychological models of language processing because they endorse the idea that meaning and grammar are not handled by a "general-purpose language processor", as he puts it, but rather they are "domain specific" - in other words, processed independently.

For his second example, Hagoort points to a brain imaging study that showed the pleasantness of a smell was rated differently depending on whether it was accompanied by the label "cheese" or "body odour". Crucially, the brain imaging data showed the verbal label affected processing in the actual smell centre of the brain. "This example illustrates something that would not so easily be found out with a behavioral method: that language information acts directly in the olfactory input system," Hagoort said.
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Hagoort, P. (2008). Should Psychology Ignore the Language of the Brain?. Current Directions in Psychological Science, 17(2), 96-101. DOI: 10.1111/j.1467-8721.2008.00556.x (Access is currently free).

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

2 comments:

  1. Anonymous3:05 am

    There are quite a few examples of neuroimaging being relevant to models of language out there. See, for example, http://dx.doi.org/10.1016/j.bandc.2005.11.008

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  2. Anonymous2:52 am

    There are many things that tie into both the brain and psychology,such as studies of the affects of drugs, one of those being the study of LSD which can make someone more prone to schizophrenia which is a disease that not only affects psychology but also neurology.

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