The well-known philosopher Jerry Fodor was one of the people who could not picture mental images in their heads. It is a disorder called aphantasia. The disorder has recently been popularised, for example, by the Firefox browser programmer Blake Ross in his widely shared FB post “Aphantasia: How It Feels To Be Blind In Your Mind”.
As early as 1880, however, Francis Galton was investigating how people are able to picture mental images in their heads. In one of his articles he notes, surprisingly, that when he asked fellow scientists about the subject, most of them thought he was pulling their leg, that nothing like “a mental image exists”.
Jerry Fodor reportedly reacted the same way when he first discussed mental images with colleagues. Fodor was so convinced that nothing of the kind exists that he considered mental images an invention and a joke of his colleagues.
If Fodor himself could think “only in language”, that is, verbally, is it not then likely that he inevitably had to come up with a theory claiming that the principle of general human thought resembles language, or perhaps even is a language similar to natural language? That is what Fodor’s hypothesis of the “language of thought” claims.
The opposite of Fodor’s linear, logical and syntactic “language of thought” is Philip Johnson-Laird’s theory of mental models. His theory says that mental models are, on the contrary, visual, spatial, associative, diagrammatic, an expression of thinking in space by means of relations between objects.
Both ways of thinking are important. It is clear that most people will have the ability to use both, even though they will prefer one of them, because it will be more dominant and more developed.
Thanks to Cristina Aguillón I learned about the disorder aphasia, which appears in people who have had a stroke and part of whose brain has died. Depending on the severity and extent of the stroke, these people partly or completely lose the ability to speak, read and write. It was originally thought that the intelligence of these people otherwise remains intact; however, current research on people with aphasia using non-verbal tests shows a decline in intelligence even on tasks that require no language.
It occurs to me that in our society people without language are more or less lost, whereas people without the capacity for mental imagery often live successful lives without ever realising that they lack this important way of reasoning.
Something tells me that aphantasia will be more common than it seems. I even think that, roughly since Gutenberg, biocultural selection has seen to it that people with aphantasia were more important to society, whereas people with aphasia or a similar verbal disorder had trouble finding partners and, consequently, offspring to whom they could pass on their genes.
There are ethnic groups that historically placed such a fundamental cultural emphasis on the verbal way of thinking that the average level of their verbal intelligence gradually increased over hundreds of years, while their visual-spatial intelligence stagnated, indeed even declined. The reason is that it was not needed for their cultural customs, work, education and survival.
This brings me to the most interesting thing that has been occupying my own mind lately: culture and its demands for certain cognitive skills is a selective mechanism that determines which genes, and therefore which cognitive abilities and ways of thinking, will be preferred in future generations. If a given culture remains relatively stable, we can expect these cognitive skills to be preferred more and more through a feedback mechanism, and also to improve in people.
Some cultures did this unconsciously, some dictators tried to do it consciously and by force. In both cases, however, this mechanism and process of selecting certain skills, above all cognitive ones, is called by a single word: eugenics.
Culture as a selective mechanism of our genes can be eugenic or dysgenic. That is, it can prefer the traits that we in Western society consider positive (intelligence, flexibility of thinking, creativity) or negative ones.
For the moment I am focusing only on one small but influential part of our culture, which influences our thinking here and now, but also establishes certain cultural mechanisms for preferring a certain way of thinking, and that part is technology.
My wildest hypothesis is that we can look at history with a method in which we look for great cultural and social changes in the way technologies and other cultural artefacts acted as selective mechanisms for a given way of thinking and given cognitive skills. If we accept this, it further follows that different technologies caused cognitive skills to develop differently within different cultures over time:
Different cultures work out different selective mechanisms of skills and ways of thinking (i.e. of genes as well)
The social constructivists are right. Intelligence is a socio-cultural construct. But perhaps in a different way than they wished and intended.