Volz and Gigerenzer Decisions under risk versus uncertainty For instance, consider the question whether Milan or Mod- take-the-best models how people infer which of two objects has ena has more inhabitants. If one has heard of Milan but not of a higher value on a criterion based on cue values retrieved from Modena, the inference is that Milan is the larger city. Note that memory (Gigerenzer and Goldstein, 1996). The heuristic is deﬁned the RH requires semi-ignorance to be applicable, meaning that if by three building blocks: one has heard of both (or neither) objects, it will not be effective. Experimental studies indicate that a large proportion of subjects Take-the-best heuristic: rely on it in uncertain situations, such as when predicting which (i) Search rule: search through cues according to their validity. tennis player will win in Wimbledon or which political candidate (ii) Stopping rule: stop search on ﬁnding the ﬁrst cue that to vote for, and by animals when choosing food (Gigerenzer and discriminates between the objects. Goldstein, 2011). These studies report a substantial correlation (iii) Decision rule: infer that the object with the positive cue value between the proportion of judgments that follow the RH and the has the higher criterion value. validity of recognition for the task, suggesting an adaptive use of the heuristic. Thus, according to this cognitive process model, information There are two competing hypotheses in the literature: that search is terminated as soon as a cue discriminates between the people use the RH in an adaptive or in an automatic way. The alternatives; other cues are not activated. For instance, if a person adaptive use requires two processes. The ﬁrst assesses whether or has heard of both Milan and Modena and recalls that Milan is a not the alternatives are recognized and hence whether the RH state capital (the most valid cue) but Modena is not, that person can be applied in principle. The second process assesses whether would stop search for further cues and infer that Milan has the the RH should be applied, which is essentially a judgment about larger population. the heuristic’s ecological rationality, that is, the match between Note that take-the-best implies a lexicographic step-by-step mind and environment. In contrast, the automatic use entails process with limited search. This process is quite different from only one process: automatically choosing the recognized alterna- weighting-and-adding all cues, which is assumed in models that tive, without considering why recognition should be predictive of postulate the integration of all cues, such as in value-based deci- the criterion. Such an automatic strategy would also be successful sion models. Experimental studies have provided strong evidence for the Milan–Modena question, where recognition is so highly that many people’s memory-based inferences are consistent with correlated with city size. the predictions of take-the-best (and inconsistent with those of In 2006, we tested these hypotheses with the help of func- adding-and-weighting models) in situations where its use is eco- tional magnetic resonance imaging (fMRI; Volz et al., 2006). logically rational (e.g., Rieskamp and Otto, 2006; Bröder, 2011). To see whether RH-based decision processes depend on addi- Speciﬁcally, experts appear to rely on simple search and stop- tional judgments of ecological rationality, which should draw on ping rules more often than novices (Garcia-Retamero and Dhami, brain areas beyond those known to reﬂect recognition memory 2009). processes, we ran two experiments. In experiment 1, participants Can cognitive neuroscience provide evidence for the hypothesis were presented with the names of two cities and asked to indi- of limited search, as deﬁned in the stopping rule of take-the-best? cate which city in each pair is larger (recognition plus inference). Khader et al. (2011) used fMRI to test the assumption that heuris- In experiment 2, participants were presented with the names of tics simplify decision making by activating long-term memory two cities and asked to indicate which city they knew in each representations of only those attributes that are necessary for the pair (recognition only). Comparing the activation results of the decision, since it is unclear from behavioral studies alone whether two experiments, we found that decision processes in both exper- using heuristics is indeed associated with limited memory search iments 1 and 2 drew on medial parietal areas, which are assumed (with the exception of reaction time studies; see Bröder and Gaiss- to reﬂect recognition memory processes. In contrast, speciﬁcally maier, 2007). Accordingly, the authors monitored the activation RH-based decision processes (in experiment 1) drew addition- of speciﬁc long-term memory representations while participants ally on the anterior medial prefrontal cortex, which is taken to made memory-based decisions using the take-the-best heuristic. reﬂect judgments of the ecological rationality of the RH in terms of Khader et al. (2011) taught their subjects to make decisions assessing one’s own sense of recognition. Thus, RH-based decision using the TTB heuristic while measuring their hemodynamic processes go beyond automatically choosing the recognized alter- response. Particularly, they let their participants ﬁrst learn by native and are guided by judgments about the ecological rationality trial and error to associate each of 16 ﬁctional company names of the RH, as reﬂected by activation in anterior medial prefrontal with a speciﬁc stimulus pattern of four binary cues (objects, cortex. houses, locations, faces). Then, participants learned how to make The study illustrates how fMRI can be used to compare compet- decisions using the TTB heuristic for a ﬁctional job selection ing hypotheses about the selection of heuristics: here, hypotheses scenario (i.e., which of two applicants is more suitable for a on automatic versus adaptive use. job). Thereafter, participants learned by trial and error (i) the importance of the different attributes for predicting which of two TAKE-THE-BEST HEURISTIC companies would be more successful, e.g., the attribute hierarchy The RH draws on the core capacity of recognition of names, faces, objects > houses > locations > faces; and (ii) which stimulus was or other stimuli. If both objects are recognized, the RH is not predictive of higher success, that is, the attribute direction. In each applicable, but the take-the-best heuristic (TTB) is. Like the RH, phase, participants learned until they satisﬁed a criterion. Frontiers in Neuroscience | Decision Neuroscience July 2012 | Volume 6 | Article 105 | 4