I was just pointed to a 1963 paper by anthropologist Jack Goody and literary historian Ian Watt, “The Consequences of Literacy” (pt 1) (pt 2), that’s well worth reading if you’re interested in such things. A sample:
Early British administrators among the Tiv of Nigeria were aware of the great importance attached to these genealogies [which "stretch some twelve generations in depth back to an eponymous founding ancestor"], which were continually discussed in court cases where the rights and duties of one man towards another were in dispute. Consequently they took the trouble to write down the long lists of names and preserve them for posterity, so that future administrators might refer to them in giving judgement. Forty years later, when the Bohannans carried out anthropological field work in the area, their successors were still using the same genealogies. However, these written pedigrees now gave rise to many disagreements; the Tiv maintained that they were incorrect, while the officials regarded them as statements of fact, as records of what had actually happened, and could not agree that the unlettered indigenes could be better informed about the past than their own literate predecessors. What neither party realized was that in any society of this kind changes take place which require a constant readjustment in the genealogies if they are to continue to carry out their function as mnemonics of social relationships…
It is obvious that the process of generation leads in itself to a constant lengthening of the genealogy; on the other hand, the population to which it is linked may in fact be growing at quite a different rate, perhaps simply replacing itself. So despite its increasing length the genealogy may have to refer to just as many people at the present time as it did fifty, a hundred, or perhaps two hundred years ago. Consequently the added depth of lineages caused by new births needs to be accompanied by a process of genealogical shrinkage; the occurrence of this telescoping process, a common example of the general social phenomenon which J.A. Barnes has felicitously termed ‘structural amnesia’, has been attested in many societies, including all those mentioned above…
Among the Vai people of western Liberia, Sylvia Scribner and Michael Cole found the ideal situation to test the effects of literacy. In the 19th century, the Vai invented a wholly original writing system for their language, a syllabic script like the one used for modern Japanese. … But since then, Vai writing has been used only for keeping commercial records and for personal letters; schools in Liberia are conducted in English, the official language, and the Moslem Vai use Arabic for religious purposes. So there is no public writing in Vai — no books or newspapers. Nor is there any formal schooling in the language; literacy is passed on from one individual to another. If there are psychological differences between Vai literates and illiterates, then, they can only be the result of literacy itself, rather than the factors that usually accompany literacy in other cultures.
In ”The Psychology of Literacy,” Miss Scribner and Mr. Cole report the results of four years of research among the Vai. … Miss Scribner and Mr. Cole subjected the Vai to a battery of psychological tests of memory and of abstract and logical thinking — asking them, for example, to sort common objects into categories and then re-sort them according to other principles, or to work out simple logical puzzles. Their surprising finding was that literacy in itself had very little effect on performance in these tests, though formal schooling did. Only when they turned to testing skills that were closely connected to literacy and letter writing, like the ability to work out rebus puzzles or to give road directions to someone who was not present, did unschooled literates do better than illiterates. Miss Scribner and Mr. Cole conclude that the mere fact of learning to read and write doesn’t bring with it any important psychological development. What matters, rather, is the uses that people make of their literacy.
If anyone knows of good recent work on this topic, I’d love to hear about it.
Via this MetaFilter thread on the Scots Gaelic origins of gospel music, which I highly recommend—there are some very knowledgeable people in the discussion.