Have you noticed that there are people who don’t really like the elderly but really enjoy their grandmother and her friends? There are people who are on the side of the poor but cannot stand to be near any homeless person. I find that sort of thing in myself and in everyone I know. The more I think about it, the more I notice a disconnect between how we view individuals and social groups. This is probably a good thing. What would you do about someone who is great, really the sort of person you like, but has the drawback of one single belief that you just can’t take? Of course, you would continue to like your friend and dislike the people with the nasty belief. When thinking about your friend you who overlook their belief and in thinking about the group with that belief, you would overlook your friend’s membership. We simple accept the disconnect.

Some recent research has shown how we do it. It has long been known that people treat inanimate and animate things differently. A person can lose the ability to recognize one category while still being able to handle the other. And other people can have the problem the other way around. This ‘double dissociation’ is assumed to show that the brain has separate ways of storing/retrieving the items in the two conceptual categories. What the new research shows is a third category that can be dissociated from these two.

The research paper is: Raffaella I. Rumiati, Andrea Carnaghi, Erika Improta, Ana Laura Diez, Maria Caterina Silveri. Social groups have a representation of their own: Clues from neuropsychology. Cognitive Neuroscience, 2014; 1 DOI: 10.1080/17588928.2013.876981. Here is the abstract:

The most relevant evidence for the organization of the conceptual knowledge in the brain was first provided by the patterns of deficits in brain-damaged individuals affecting one or another semantic category. Patients with various etiologies showed a disproportionate impairment in producing and understanding names of either living (fruits, vegetables, animals) or nonliving things (tools, vehicles, clothes). These double dissociations between spared and impaired recognition of living and nonliving things led to suggest that these categories are discretely represented in the brain. Recently social groups were found to be represented independently of traditional living and nonliving categories. Here we tested 21 patients with different types of primary dementia with three word sorting tasks tapping their conceptual knowledge about living and nonliving entities and social groups. Patients double dissociated in categorizing words belonging to the three categories. These findings clarify that knowledge about social groups is distinct from other semantic categories.

More of these sorts of categories are not unheard of. Bantu languages have noun classes in their grammar that correspond roughly to categories like this. For Swahili there are 18 classes, roughly: persons, groups of persons, plants, groups of plants, fruits, groups of fruit, things, groups of things, animals, groups of animals, abstracts, actions, and 3 to do with locations.

In 2012 researchers at MIT showed that the brain organizes objects based on size. “By looking at the arrangement of the responses, they found a systematic organization of big to small object responses across the brain’s cerebral cortex. Large objects, they learned, are processed in the parahippocampal region of the brain, an area located by the hippocampus, which is also responsible for navigating through spaces and for processing the location of different places, like the beach or a building. Small objects are handled in the inferior temporal region of the brain, near regions that are active when the brain has to manipulate tools like a hammer or a screwdriver.”

It seems a puzzle whether these divisions are linguistic or not. Are categories reflecting how we process some types of objects, or are they the categories we learn with our mother tongue? Do we naturally have a lot of categories but lose many, or have naturally a few and create many more? What is the cost/benefit of categories – are they costly to maintain and work with, or do they make thinking easier?