Literally changing the brain

Can culture change basic brain anatomy? Evidence that bears on this question is hard to come by, and the contribution by Castro-Caldas and colleagues in this issue is therefore particularly welcome. Their paper shows direct evidence for changes in the functional organization of the adult brain as a result of a decidedly cultural cause: having learned to read. Obviously, behaviour and brain activation will be changed by learning. Indeed there have been studies showing differences in brain activation by comparing performance at early and late stages of learning (see Passingham, 1997). That is not the point. What is shown here is a difference in how literate and illiterate people speak, without so much as a glimpse of print. Castro-Caldas and colleagues took advantage of a rapidly vanishing opportunity to study the effect of literacy without confounding social or medical factors. They compared people who were modestly literate and those who were illiterate, all from the same small town in southern Portugal. In this community it used to be quite common to keep the eldest daughter at home to help with the work, while the younger ones were sent to school for four years. Even those who had been to school did not read very much, and both groups of participants were screened to be of equal level in a number of simple vocabulary and general knowledge tests. All this makes any differences obtained even more remarkable. Morais et al. (1979) were the first to grasp the opportunity of comparing literate and illiterate Portuguese adults of the same sociocultural background. They showed that illiterates performed very poorly in spoken language games like phoneme deletion (e.g. take away the first sound of 'porto', resulting in 'orto'). They also found that illiterates had poorer short term verbal recall. Similar studies have been conducted with non-alphabetic languages, notably by Read et al. (1986), with similar results. These studies have confirmed that the effect is due specifically to the alphabetic principle of graphically coding segmented speech sounds. In the present paper, illiterates are shown to perform poorly at listening and repeating words, a task just as remote from writing as the language game of phoneme deletion. The conclusion from this and other studies of literacy acquisition is that learning to read has a profound effect on the way the brain analyses speech and how the product of this analysis feeds into memory. The present study …