The great advantage of Tenenbaum and Griffiths's model is that it incorporates both specific and general prior knowledge into category learning. Two phenomena are presented as supporting the detailed assumptions of this model. However, one phenomenon, effects of diversity, does not seem to require these assumptions, and the other phenomenon, effects of sample size, is not representative of most reported results. [Tenenbaum & Griffiths]

A common code for integrating perceptions and actions was relevant for simple behavioral guidance well before the evolution of cognitive abilities. We review proposals that representation of to-be-produced events played important roles in early behavior, and evidence that the neural mechanisms supporting such rudimentary sensory predictions have been elaborated through evolution to support the cognitive codes addressed by TEC.

Hertwig and Ortmann imply that failure of many behavioral psychologists to observe several central methodological principles of experimental economics derives mainly from differences in disciplinary culture. I suggest that there are deeper philosophical causes, based (ironically) on a legacy of methodological individualism in psychology from which economists have substantially cured themselves through use of game theory. Psychologists often misidentify their objects of study by trying to wrench subjects out of their normal behavioral contexts in games.

In the course of evolution organisms change both their morphology and their physiology in response to ever-changing environmental selection pressures. This process of adaptation leads to an “internalization,” in the sense that external regularities are in some way “imitated” by the living system. Countless examples illustrate the usefulness of this metaphor. However, if we concentrate too much on Shepard's “universal regularities in the world,” we run the risk of overlooking the many more fascinating evolutionary details which alone have made, and still make possible the evolution of diversity on earth. [Shepard]

Webb's scheme for classifying behavioral models is applicable to a wide range of theories and simulations, nonrobotic as well as robotic. It is suggested that a meta-analysis of existing models, characterized according to the proposed scheme, could identify regions of the seven-dimensional modelling space that are particularly likely to lead to new insights in understanding behavior.

Thelen et al.'s account of cognition as the dynamic interaction of processes of perceiving, reaching, and remembering within a movement planning field is a useful articulation of the Piagetian concept of sensorimotor cognition. The claim that the same kind of analysis applies to all kinds of cognition at all ages, however, is questioned in light of the distinction between sensorimotor and symbolic cognition.

Stoffregen & Bardy provide grounds to suppose that specification requires global arrays and that this information is used by perceptual systems. Three conclusions follow from this supposition; (1) global specification will be taken seriously only if additional examples are discovered; (2) research into single-sense information must take global information into account, and (3) ecological psychologists must account for perceptions based upon non-specific information.

The theory of event coding by Hommel et al. proposes that feature binding is a central component of action planning. To evaluate the binding hypothesis, we consider findings from studies of action-perception interference and bimanual movements. We argue that although binding of action features may be a valuable concept, interference from partial feature overlap does not provide a parsimonious account for the observed phenomena.

Psychologists have long debated the underlying cause of infants' perseverative reaching. Thelen et al. explain the error in terms of general processes that make goal-directed actions to remembered locations. The context- and experience-dependent nature of their model implies that there is no single cause of the A-not-B error, and, more generally, no core essence to cognitive development.

Webb has articulated a clear, multi-dimensional framework for discussing simulation models and modelling strategies. This framework will likely co-evolve with modelling. As such, it will be important to continue to clarify these dimensions and perhaps add to them. I discuss the dimension of generality and suggest that a dimension of integrativeness may also be needed.

The commentary is in general agreement with Roger Shepard's view of evolutionary internalization of certain procedural memories, but advocates the use of Lie groups to express the invariances of motion and color perception involved. For categorization, the dialectical pair is suggested. [Barlow; Hecht; Kubovy & Epstein; Schwartz; Shepard; Todorovič]

Standard practices in experimental economics arise for different reasons. The “no deception” rule comes from a cost-benefit tradeoff; other practices have to do with the uses to which economists put experiments. Because experiments are part of scientific conversations that mostly go on within disciplines, differences in standard practices between disciplines are likely to persist.

Modified action, either artificially induced or occurring naturally during life-span, alters organization and processing of primary somatosensory cortex, thereby serving as a predictor of age-related changes. These findings, together with the interconnectedness between motor-sensory systems and temporally-distributed processing across hierarchical levels, throws into question a sharp division between early perception and cognition, and suggest that composite codes of perception and action might not be limited to higher areas.

In perception science, an alternative to focusing on individual sensory systems is to describe the environment to be perceived. We focus on the emergent dynamics of human-environment interactions as an important category of the environment to be perceived. We argue that information about such dynamics is available in subtle patterns of movement variability that, of necessity, stimulate multiple sensory systems.

The rhetoric of hypothesis testing implies that game theory is not testable if a negative result is blamed on any auxiliary hypothesis such as “rewards are inadequate.” This is because either the theory is not falsifiable (since a larger payoff can be imagined, one can always conclude that payoffs were inadequate) or it has no predictive content (the appropriate payoff cannot be prespecified).

As Hecht points out, finding unequivocal evidence for phylogenetic knowledge structures is problematic, if not impossible. But if phylogeny could be dropped, then internalization starts to resemble the “theory theory” approaches of developmental psychology. For example, an appreciation of falling objects leads to a very strong bias that could be regarded as internalized knowledge acquired during ontogeny. [Hecht; Shepard]

The “A-not-B” error is consistent with an old memory principle, Jost's Law. Quantitative properties of the effect can be explained by a dynamic model for habituation that is also consistent with Jost. Piaget was well aware of the resemblance between adult memory errors and the “A-not-B” effect and, contrary to their assertions, Thelen et al.'s analysis of the object concept is much the same as his, though couched in different language.

Using robots that operate in the real world as opposed to computer simulations of animal behavior is a form of modeling that may provide some biological insights. However, since engineering principles and materials differ significantly from those used in biology, one should be extremely cautious in interpreting robot biomimicry as providing an explanation of biological mechanisms.

The claim that perception and action are commonly coded because they are indistinguishable at the distal level is crucial for theories of cognition. However, the consequences of this claim run deep, and the Theory of Event Coding (TEC) is not up to the challenge it poses. We illustrate why through a brief review of the evidence that led to the motor theory of speech perception.

Stoffregen & Bardy's primary motivation for rejecting current views on specification in favor of the global array is that current forms of specification in single-energy arrays allow the ambiguous or inadequate specification of reality. I show that this motivation is not justified, and that the global array concept still falls prey to inadequate specification.