TLRP researcher Michael Eraut (2006) argues in Modes of Workplace Learning and the Factors that Affect it that in a number of professions expertise comprises increasingly intuitive decision-making, in which not only pattern recognition but also rapid responses to developing situations are based on tacit knowledge - the tacit application of tacit rules. He also differentiates between different modes of cognition. Tacit knowledge appears in three different forms:

• Situational understanding based largely on experience and remaining mainly tacit
• Standard, routinised procedures are developed for coping with the demands of work without suffering from information overload. Some of them may have begun as explicit procedural knowledge then become automatised andincreasingly tacit.
• Increasingly intuitive decision-making, in which not only pattern recognition but also rapid responses to developing situations are based on tacit knowledge - the tacit application of tacit rules.

• Eraut M. (2000) Non-formal learning and tacit knowledge in professional work, British Journal of Educational Psychology, Volume 70, Number 1, March 2000 , pp. 113-136. Three types of tacit knowledge are discussed: tacit understanding of people and situations, routinised actions and the tacit rules that underpin intuitive decision-making. They come together when professional performance involves sequences of routinised action punctuated by rapid intuitive decisions based on tacit understanding of the situation. Four types of process are involved (reading the situation, making decisions, overt activity and metacognition) and three modes of cognition (intuitive, analytic and deliberative). The balance between these modes depends on time, experience and complexity. Where rapid action dominates, periods of deliberation are needed to maintain critical control. Tacit knowledge is personal knowledge which may be used uncritically because people either believe that it works well for them or lack the time and/or disposition to search for anything better – the latter is a common feature of situations where people are overworked or alienated. But in more technical areas, or where more strategic decisions are involved, tacit knowledge is more likely to be used for generating hypotheses or possible sources of action, which are then checked out against other evidence or discussed with other people. This behaviour is characteristic of medical diagnosis and decision-making in a wide range of naturalistic settings. Tacit knowledge does not arise only from the implicit acquisition of knowledge but also from the implicit processing of knowledge. The distinguishing feature of experts is not how much they know, but their ability to use their knowledge, because that knowledge has been implicitly organised as a result of considerable experience for rapid, efficient and effective use (Schmidt and Boshuizen, 1993). Most of the episodes from which tacit knowledge is accrued occur within social contexts, and actions, discourse and interpretations of events, both during and after the episodes, are likely also to be influenced by what is noticed and/or remembered by other actors. Thus, an individual’s implicit acquisition and processing of tacit knowledge is influenced by socialisation processes and the local workplace culture.

• Eraut M. (2004) Informal learning in the workplace, Studies in Continuing Education, Volume 26, Number 2, 2004 , pp. 247-273. He seeks to deconstruct the 'key concepts' of informal learning, learning from experience, tacit knowledge, transfer of learning and intuitive practice. ‘The relationship between time and cognition is probably interactive: shortage of time forces people to adopt a more intuitive approach, while the intuitive routines developed by experience enable people to do things more quickly. Crowded contexts also force people to be more selective with their attention and to process their incoming information more rapidly. Under conditions of rapid interpretation and decision making, meta-processes are limited to implicit monitoring and short, reactive reactions. But as more time becomes available the role of meta-processes becomes more complex, expanding beyond self-awareness and monitoring to include the framing of problems, thinking about the deliberative process itself and how it is being handled, searching for relevant knowledge, introducing value considerations, and so on. Even when there is no emergency, experienced people typically prefer to do many things quickly and smoothly if they are confident in their own proficiency. However, there are also situations in which speed beyond what even proficient workers consider appropriate is forced by pressure for productivity. Then quality falls, the level of risk is higher and job satisfaction plummets. Both the development of proficiency and learning to cope with pressures for rapid action involve routinization and further work; but whereas the routines associated with proficiency lead to improvement in both quality and productivity, coping routines increase productivity at the expense of quality. In either case, routinization leads to knowledge becoming less explicit and less easily shared with others, i.e. more tacit. Tacit knowledge of this kind is also likely to lose value over time because circumstances change, new practices develop and people start to take shortcuts without being aware that they are reducing their effectiveness.’ (p. 261).

The relevance of intuition in educational and professional settings is developed further in ‘The Intuitive Practitioner: a critical overview’, in Atkinson, T, Claxton, G (Eds) (2000) The Intuitive Practitioner. Open University Press 253-268. In case you cannot get hold of the, there is linked book review essay at: Inviting Intuitive Understandings in Teaching and Professional Practices: Is Intuition Relationally and Culturally Neutral?

Other TLRP research focused on the "Recognition of Tacit Skills and Knowledge in Work Re-entry". The project, led by Karen Evans, was carried out as a part of the TLRP Research Network 'Improving Incentives to Learning in the Workplace'. The study investigated the part played by tacit forms of personal competences in the education, training and work re-entry of adults with interrupted occupational or learning biographies. It aimed to identify ways in which the recognition and deployment of tacit skills can strengthen their learning success and learning outcomes in new learning and working environments. The part played by such skills and knowledge in work performance is recognised but not well understood. These implicit or hidden dimensions of knowledge and skill are key elements of 'mastery', which experienced workers draw upon in everyday activities and continuously expand in tackling new or unexpected situations. What is known about tacit skills at work has come mainly from studies of development of expert knowledge in particular occupations or professions. There is a tendency to assume that adults develop and use their skills in more or less continuous occupational careers. The project on tacit skills and work re-entry has taken as its starting point the importance of understanding better the part played by tacit forms of personal competences in the education, training and work re-entry of adults with interrupted occupational or learning biographies. It has aimed to identify ways in which the recognition and deployment of tacit skills can strengthen their learning success and learning outcomes in new learning and working environments.

To uncover the tacit skills of adults, sixty-one people studying at six different colleges in London were interviewed. The next stage of research involved tracking them into their workplaces and reviewing with them what they have gained from their learning and how this facilitates their learning achievements and outcomes in new learning and working environments. The results showed that:

• students' learning outcomes have both "formal"and "informal" dimensions, with informal outcomes identified as those associated with self-assurance, increased capability, improved attainments and greater abilities to exercise control over their situations and environments;
• harnessing tacit skills in stimulating and expansive working environments sustains learning outcomes and facilitates the process of work re-entry;
• the way employees experience an expansive environment has to do with the feeling of being a part of a team, allowing them to deploy their tacit skills in ways, which enhance their confidence and self-assurance, whereas a restrictive environment is often associated with being an outsider or mere observer in the workplace.

Recognising Tacit Skills: some of the key findings

• Adults often gain tacit skills from a range of life and work experiences, but do not necessarily think they have gained anything of value.
  
• There is a link between recognition, deployment and development of tacit skills.
  
• Positive deployment and recognition of their skills strengthens their learning success.
  
• Gender differences are important: males and females perceive their tacit skills differently. Females value their skills acquired as a result of household and family experience, although they claim that such skills are not recognised by the job market except in low status caring and 'women's work'. Males tend to disregard skills gained outside formal learning while attaching importance to 'formally acquired' skills.
  
• Recognising and deploying tacit skills in stimulating, 'expansive' workplace/learning environments sustains learning outcomes; they boost confidence as well as ability to resist imposition by others of inappropriate expectations.
  
• Modelling of individual learning processes can provide better understanding of adult returners' experiences in re-entering work.

Footnotes:

One problem with this area is that in practice the neat divisions of different types of knowledge and understanding start to become less sharp when looking at complex behaviours particularly when a time dimension is introduced. Some aspects of tacit knowledge, which are not readily articulated, may become more explicit through processes of active reflection, while other aspects remain tacit. Also even if particular episodes are being recalled they may not be accurately recalled or aspects of several episodes may become mixed. So aggregated information being used for a decision may be tacit, explicit or mixed with some aspects of selection and interpretation of information from these episodes being harder to explain than others, and the reasons given may be partly influenced by post-hoc rationalisations.

The ideas expressed here are also linked to understandings of the differences between between episodic, semantic and procedural memory. Episodic memory holds specific, personally experienced events. Semantic memory holds knowledge linked to meanings, understandings and concepts; transcends particular episodes; and is most often acquired through formal teaching and learning, or through reflection on episodes from experience. Procedural memory is the long-term memory of skills and procedures, and is the basis of knowledge of 'how to' act in given situations. Tacit knowledge, which is not readily articulated, develops in particular situations and if it is used at a later date one important advantage is it has already been contextualised.