Thursday, February 10, 2011

Phrenology, Then and Now

In the November 2010 issue of Perspectives in Psychological Sciences, a Special Section on "Neuroimaging: Voodoo, New Phrenology, or Scientific Breakthrough?" (Diener, 2010) looks back at the infamous paper by Vul et al. (2009) and forward into the future. In one of the articles, an extended analogy is made between modern neuroimaging and the phrenology of yore (Poldrack, 2010):
Imagine that fMRI had been invented in the 1860s rather than the 1990s. Instead of being based on modern cognitive psychology, neuroimaging would instead be based on the faculty psychology of Thomas Reid and Dugald Steward, which provided the mental “faculties” that Gall and the phrenologists attempted to map onto the brain. Researchers would have presumably jumped from phrenology to fMRI and performed experiments manipulating the engagement of particular mental faculties or examining individual differences in the strength of the faculties. They almost certainly would have found brain regions that were reliably engaged when a particular faculty was engaged and potentially would also have found regions in which activity correlated with the strength of each faculty across subjects.
Gall's ambition and vanity are now 'activation for judgment about self versus others', localized to medial prefrontal cortex. Friendly attachment/fidelity have been transformed into 'viewing a friend versus viewing a stranger', associated with right temporoparietal cortex.

-- click on image for larger view--

Table 1 (Poldrack, 2010). A Mapping of Gall's 27 Faculties to Potentially Related Neuroimaging Research.
Although few today would hold that 19th century faculty psychology is an accurate description of the structure of the mind, we can likely all agree that if the phrenologists had created task manipulations to isolate their proposed faculties using fMRI, something would have “lit up.” What would the patterns of activation associated with these faculties have looked like? If we believe, as I think most would agree, that each of the phrenologists' putative faculties relies in actuality upon a combination of basic mental operations, then we would likely expect that the maps obtained for a given faculty would include a large set of activated regions that would tend to overlap across tasks meant to tap into different faculties. Regardless, one can be almost certain that Gall and his contemporaries would have taken these neuroimaging results as evidence for the biological reality of his proposed faculties.
But we know better now, don't we? Because Neural Networks Debunk Phrenology!
The studies show that network interactions among anatomically discrete brain regions underlie cognitive processing and dispel any phrenological notion that a given innate mental faculty is based solely in just one part of the brain.
Does anyone really believe in phrenology any more? Who advocates such a view? Cognitive neuropsychologists? Single-unit neurophysiologists? OR has localization of function in discrete networks (rather than an individual structure or a bump on the head) become the new phrenology? I think the story goes like this: complex adaptive behavior is an emergent property of network interactions. This is certainly not a new idea (see any number of publications by Joaquin Fuster)...

According to Poldrack (2010), neuroimaging research strategies have evolved from “where” (blobology or neophrenology) to “what” (characterize function of a specific brain region) to “fractionation” (determine whether different mental processes engage different brain regions). Ultimately, localization of function is still the final goal... as it was for the original phrenologists:
Phrenology teaches us that in this life every act of the mind is performed through the instrumentality of the brain, and that peculiar states of this organ invariably accompany particular mental dispositions.

-M.B. Sampson Esq. (1842)


Diener E (2010). Neuroimaging: Voodoo, New Phrenology, or Scientific Breakthrough? Introduction to Special Section on fMRI. Perspectives on Psychological Science 5:714-715.

Poldrack, R. (2010). Mapping Mental Function to Brain Structure: How Can Cognitive Neuroimaging Succeed? Perspectives on Psychological Science, 5 (6), 753-761 DOI: 10.1177/1745691610388777


Vul E, Harris C, Winkielman P, Pashler H (2009). Puzzlingly High Correlations in fMRI Studies of Emotion, Personality, and Social Cognition. Perspectives on Psychological Science 4:274-290.

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