Tversky and Kahneman (1974) originally discussed three main heuristics: availability, representativeness, and anchoring-and-adjustment. Research on judgemental forecasting suggests that the type of information on which forecasts are based is the primary factor determining the type of heuristic that people use to make their predictions. Specifically, availability is used when forecasts are based on information held in memory; representativeness is important when the value of one variable is forecast from explicit information about the value of another variable; and anchoring-and-adjustment is employed (...) when the value of a variable is forecast from explicit information about previous values of that same variable. Although there has been increased emphasis on the adaptiveness of heuristics and increased interest in specifying their use in terms of computational models, this way of structuring our knowledge about judgemental forecasting continues to be a useful one. I use it to frame discussion of some recent debates in the area. (shrink)

I make three points. First, processors and depletable resources should not be regarded as alternative means of processing information: they are both necessary. Second, comparing a processor account with a rational allocation mechanism to a depletable-resources account without one is not a fair comparison. Third, depletable resources can act as signals as well as fuels.

The previous papers raise a number of issues. How should we develop task typologies both to separate judgement from related cognitive tasks and to classify tasks within the judgement domain? Are there grounds for selecting between models of judgement when empirical tests fail to do so? What techniques can be used to find out more about the cognitive processes underlying judgement behaviour? I discuss these issues and give a brief assessment of the current state of play in this rapidly changing (...) area. (shrink)