Henrich et al. reject the “selfishness axiom” within a narrowly-defined economic model, and are premature in claiming that they have demonstrated cross-cultural variability in “selfishness” as defined in broader evolutionary theory. We also question whether a key experimental condition, anonymity, can be maintained in the small, cohesive, social groupings employed in the study.

Thelen et al. have a strong case for linking behavior with mind through nonrepresentational dynamics. Their case linking mind with brain is less compelling. Modified avenues are proposed for further exploration: greater emphasis on the dynamics of perception; use of chaotic instead of deterministic dynamics with noise; and use of intentionality instead of motivation, taking advantage of its creative dynamics to model genesis of goal-directed behaviors.

Byrne & Russon suggest that the production of action by primates is hierarchically organised. We assess the evidence for hierarchical structure in the comprehension of action by primates. Focusing on work with human children we evaluate several possible indices of program-level comprehension.

Any model aiming to explain the enjoyment of negative emotions in the context of the arts should consider how works of art are able to induce emotional responses in the first place. For instance, research on empathy and the arts suggests that the psychological processes that mediate the enjoyment of sadness and horror may be fundamentally different.

The commentaries suggest many important improvements to the target article. They clearly distinguish two varieties of rationalization – the traditional “motivated reasoning” model, and the proposed representational exchange model – and show that they have distinct functions and consequences. They describe how representational exchange occurs not only by post hoc rationalization but also by ex ante rationalization and other more dynamic processes. They argue that the social benefits of representational exchange are at least as important as its direct personal benefits. Finally, they construe our search for meaning, purpose, and narrative – both individually and collectively – as a variety of representational exchange. The result is a theory of rationalization as representational exchange both wider in scope and better defined in mechanism.

The continuous ongoing mentation is experienced as dreams in some functional states. Mentation occurs with high speed, is driven by individual memory, and uses state-dependent processing strategies, context material, storage options, and retrieval access. Retrieval deserves more attention. Multiple state-shifts owing to individual meaning as extracted also during sleep concatenate dream narratives and define access to segments for awake recall.

[Hobson et al.; Nielson; Solms]

PET studies using classical conditioning paradigms are reported. It is emphasized that PET studies show “cerebellar involvement” and not “specific function” in learning paradigms. The importance of dissociating motor performance and learning deficits in human lesions studies is demonstrated in two exemplary studies. The different role of the cerebellum in adaptation of postural reflexes and learning of complex voluntary arm movements is discussed, [THACH]

Constructivism is the most recent in a long line of failed attempts to discredit nativism. It seeks support from true (but irrelevant) facts, wastes its energy on straw men, and jumps logical gaps; but its greatest weakness lies in its failure to match nativism's explanation of a wide range of disparate phenomena, particularly in language acquisition.

The synthesis provided by Kline in the target article is noteworthy, but ignores the inseparable role of play in the evolution of learning and teaching in both humans and other animals. Play is distinguished and advantaged by its positive feedback reinforcement through pleasure. Play, especially between adults and infants, is probably the platform from which human learning and teaching evolved.

The qualitative division between domain-general and domain-specific cognition is unsubstantiated. The distinction is instead better viewed as opposites on a gradual scale, which has more explanatory power and fits current empirical evidence better. We also argue that causal cognition may be more general than social learning, which it often involves.

Because of the complexity of human emotional responses, invariants must be sought not in the responses themselves, but in their generating mechanisms. Lindquist et al. show that functional locationism is a theoretical dead end; their proposed mechanistic framework is a first step toward better models of emotional behavior. We caution, however, that emotions may still be quasi-natural perceptual types.

This commentary focuses on the nature of combinatorial properties for speech and the locus equation. The presence of some overlap in locus equation space suggests that this higher order property may not be strictly invariant and may require other cues or properties for the perception of place of articulation. Moreover, combinatorial analysis in two-dimensional space and the resultant linearity appear to have a “special” status in the development of this theoretical framework. However, place of articulation is only one of many phonetic dimensions in language. It is suggested that a multidimensional space including patterns derived in the frequency, amplitude, and time domains will be needed to characterize the phonetic categories of speech, and that although the derived properties ultimately may not meet the conditions of linearity, they will reflect a higher order acoustic invariance.