Tacit knowledge and
Tacit (silent) knowledge (Polanyi, 1958) and implicit learning (see Berry [ed.] 1997) have in common the idea of not knowing what you do know or have learned. "Tacit knowledge" has been all but hi-jacked by management gurus (following the economist Friedrich Hayek), who use it to refer to the stock of expertise within an organisation which is not written down or even formally expressed, but may nevertheless be essential to its effective operation.
Originally, Polanyi's interest was in the kind of knowledge which we routinely use and take for granted, such as the ability to recognise the face of a friend: it is irreducible to explicit propositional knowledge and cannot be articulated. It cannot therefore be taught, although of course there is obvious evidence that it can be learned or acquired. It may therefore (and here I wander away from the formal theory) be associated with Gestalt understanding, and procedurally — in the form of "know-how" — with a "knack" for doing something.
If tacit knowledge is about the content of what is learned, implicit learning is about the process, and it remains a contentious debate in psychology. A typical experiment in the field is to expose subjects to strings of letters which are governed by orderly rules (or a "grammar"), such as DEFKLM and JKLPQR, and others which are not: the subjects are not expected to try to articulate the rules. The subjects are later shown further sets of letters and asked to say which are "grammatical" and which not: they tend to be able to distinguish between them without knowing quite how they do it (Reber, 1967). This is taken as evidence that they have "unconsciously" learned a rule: not only can they not specify the rule, but they do not even know that they have learned a rule.
However, in learning in the professions in particular, the process of acquiring the "know-how" of the mature practitioner is still little understood, and its relationship with formal training remains problematic. Berry (1997) reports that in one of her experiments:
It was found that in both cases, practice significantly improved ability to control the tasks, but had no effect on ability to answer post-task, written questions. In contrast, verbal instructions about the best way to control the tasks had no significant effect on control performance, although they did make people significantly better at answering the questions. [...] these basic findings have been replicated and extended in a number of follow-on studies [...] (Berry 1997:2)It is still not clear where this area of research is leading, but it may well be particularly important for educational practice in the future. The quotation certainly poses some interesting questions about skill development (in teaching, for example), and the relevance or otherwise of the ability to talk (or write—for assessment purposes) about it!
See also the "progression of competence" and "situated learning" models; implicit learning also has some relevance to Bateson's original observations about how the skill of learning itself can change, which led to the identification of his levels of learning. And see some of the wider considerations about forms of knowledge, too.
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