Byrne has written a terrific book that is, nevertheless, based on a mistaken assumption – that imagination is largely rational. I argue in this commentary that her book follows very well, if one accepts her assumption of rationality, but that the bulk of the evidence available to us contradicts this assumption.

Captive or experimental studies may be of greater utility than field studies in documenting novel behaviors. Social hierarchy affects the spread of innovations. Innovative species should also be found in cases where sociality is low or absent.

Jung & Haier (J&H) have done an admirable job of solving the wrong problem. Their article does not show “where in the brain is intelligence,” because intelligence resides not in the brain but, rather, in the interaction of brain and environment. I describe four reasons why the article does not adequately localize intelligence in the brain.

Gintis argues that disciplinary models of human behavior are incompatible. However, his depiction of the discipline of anthropology relies on a broad generalization that is not supported by current practice. Gintis also ignores the work of cognitive anthropologists, who have developed theories and methods that are highly compatible with the perspective advocated by Gintis.

Human responses to probabilities can be studied through gambling and through experiments presenting biased sequences of stimuli. In both cases, participants are sensitive to base rates. They adjust automatically to changes in base rate; such adjustment is incompatible with conformity to Bayes' Theorem. ”Base-rate neglect” is therefore specific to the exercises in mental arithmetic reviewed in the target article.

The formulation of the conditional probability in classical tasks does not guarantee the effective transmission of the independence of the hit rate from the base rate. In these kinds of tasks, data are all available, but subjects are able to understand them in the specific meanings proper to a specialized language only if these are adequately transmitted. From this perspective, the partitive formulation should not be considered a facilitation, but rather, a way of effectively transmitting the conditional probability.

Psychological science can benefit from a theoretical unification with other social sciences. Social psychology in particular has gone through cycles of repression, denying itself the opportunity to see the calculating element in human interaction. A closer alignment with theories of evolution and theories of interpersonal (and intergroup) games would bring strategic reasoning back into the focus of research.

Indirect identification of innovations in wild populations involves inferring past, unobserved behavioral events. Such historical inference can make simple use of present distribution patterns of differently behaving individuals, but population genetic studies are a potential source of complementary relevant information. Methodological lessons can be taken from phylogeography, that is, molecular approaches to the history of population spatial distribution patterns and gene flows. Opportunities for such studies in primates should increase with the developing population genetic studies used for management and conservation purposes.

How the rational imagination develops remains an open question. The ability to imagine emerges early in childhood, well before the ability to reason counterfactually, and this suggests that imaginative thought may facilitate later counterfactual ability. In addition, developmental data indicate that inhibitory control may also play a role in the ability to reason counterfactually.

High-order constructs such as intelligence result from the interaction of numerous processing systems, one of which is language. However, in determining the role of language in intelligence, attention must be paid to evidence from lesion studies and, in particular, evidence of dissociation of functions where high-order cognition can be demonstrated in face of profound aphasia.

Consistent with Barbey & Sloman (B&S), it is proposed that performance on Bayesian inference tasks is well explained by nested sets theory (NST). However, contrary to those authors' view, it is proposed that NST does better by dispelling with dual-systems assumptions. This article examines why, and sketches out a series of NST's core principles, which were not previously defined.

“Where in the brain is intelligence?” is an intriguing question, and Jung & Haier (J&H) resist the temptation to provide a simple answer. Their concept tries to integrate and transcend previous findings, and, while omitting the contributions from complementary methods, results seem to converge. Whether similarities or differences in such networks are more important, though, is still open for discussion.

Ramsey et al.'s article provides a more sensitive framework for comparative innovation than others' operationalisations have done. Nevertheless, a methodology has to be elaborated in order to determine to what degree a behaviour is novel. Psychological processes have to be considered when evaluating the value of reference groups and in order to figure out where to look for innovation.

Byrne (2005) demonstrates that reasoning and imagination are logical and governed by the same processing principles. In extending those principles to other forms of imaginative functioning, however, problems arise. The meaning of “true possibility” is stretched, and the causal role of the principles is not well established. Nevertheless, consideration of the extent to which ordinary cognitive processes govern creative functioning is valuable.

There are two roadblocks to using game theory as a unified theory of the behavioral sciences. First, there may not be a single explanatory framework suitable for explaining psychological processing. Second, even if there is such a framework, game theory is too limited, because it focuses selectively on decision making to the exclusion of other crucial cognitive processes.

The article by Barbey & Sloman (B&S) provides a valuable framework for integrating research on base-rate neglect and respect. The theoretical arguments and data supporting the nested set model are persuasive. But we found the dual-process account to be under-specified and less compelling. Our concerns are based on (a) inconsistencies within the literature cited by B&S, and (b) studies of base-rate neglect in categorization.

When creating alternatives to reality, people often feel emotions in response to these imaginary worlds. I argue that these emotions serve an important purpose. They signal how the world could have been better and prioritize actions to bring this better world about.

Overall mean performance on intelligence tests by brain-damaged patients with focal lesions can be misleading in regard to localization of intelligence. The widely used WAIS has many subtests that together recruit spatially distant neural “centers,” but individually the subtests reveal localized functions. Moreover, there are kinds of intelligence that defy the localizationist approach inferred from brain damage.

Ramsey et al. present an ingenious method to study behavioral novelty under field conditions within relatively narrow time constraints. This evokes discussion of lateral spread of innovation from individual to individual versus vertical spread from generation to generation. This discussion of incipient culture helps to place the traditional biological tool of cross-fostering into philosophical and anthropological context.

This commentary suggests that an equilibrium framework may be retained, in an evolutionary model such as Gintis's and with more satisfactory results, if rationality is relaxed in a slightly different way than he proposes: that is, if decisions are assumed to be related to rewards probabilistically, rather than with certainty. This relaxed concept of rationality gives rise to probabilistic equilibria.