The fish-sharing patterns on Ifaluk Atoll underscore several limitations of the explanations of food sharing offered by Gurven and suggest that non-foraging labor activities may provide insights into reciprocity and punishment relevant for understanding food-sharing patterns. I also argue that future food-sharing studies should focus on signaling rather than resource holding potential (RHP).

Each of the food-sharing models that Gurven considers demands unique cognitive capacities. Reciprocal altruism, in particular, requires a suite of complex abilities not required by alternatives such as tolerated scrounging. Integrating cognitive constraints with comparative data from other species can illuminate the adaptive benefits of food sharing in humans.

I agree with Gurven that costly signaling can explain food-sharing phenomena. However, costly signaling may also explain the role of food sharing in deterring rivals. Details of food-sharing interactions may reveal gains and losses in the social prestige of the interacting parties. The evolutionary models of kin selection and of reciprocal altruism are unstable and should be avoided.

Empirical data on food sharing in native Dolgan, Nganasan, and Nenets communities in Siberia provide evidence for hunter control over big game and fish, as well as likely benefits of inter-household sharing. Most food sharing occurs with kin and, thus, kin-selection-based nepotism cannot be ruled out. Reciprocal interhousehold sharing at meals occurs less often. Social context is discussed.

Four models commonly employed in sharing analyses (reciprocal altruism [RA], tolerated scrounging [TS], costly signaling [CS], and kin selection [KS]) have common features which render rigorous testing of unique predictions difficult. Relaxed versions of these models are discussed in an attempt to understand how the underlying principles of delayed returns, avoiding costs, building reputation, and aiding biological kin interact in systems of sharing. Special attention is given to the interpretation of contingency measures that critically define some form of reciprocal altruism.

The relevance of chaotic itinerancy and other types of exotic dynamical behavior described by Tsuda (2001) certainly goes beyond the scope of his target article. These concepts of dynamics may offer a general framework for the understanding of complexity, which could help to restructure the analysis and conceptualization of mental states in novel ways, providing insights for the philosophy of mind.

Kampis proposes the study of chaotic itinerancy, pointing out its significance in domains of cognitive science and philosophy. He has discovered in the concept of chaotic itinerancy the possibility for a new dynamical approach that elucidates mental states with a physical basis. This approach may therefore provide the means to go beyond the connectionist approach. In accordance with his theory, I here highlight three issues regarding chaotic itinerancy: transitory dynamics, diversity, and self-modifying system.

Hommel et al. (2001) try to explain the emergence of distal representations by an evolutionary account which includes their theory of event coding. A closer look at the way the terms “distal representations” and “representations of events” are defined reveals, however, that their hypothesis of a common code for perceived and to-be-produced events is in fact superfluous. Moreover, it shows that they mix up empirical facts with conceptual/definitional facts in the second assumption of their explanation.

In contrast to Pylyshyn's view, there is no such thing as “reasoning in general.” Different types of reasoning tasks are solved with different reasoning strategies. A more specific null hypothesis is that spatial inference with mental images involves the same representational formalism as that of spatial inference with mental models. There is no evidence that this hypothesis must be rejected.

Assuming that the vehicle of imaginal thought is a spatial model may not be quite as egregious an error as assuming it is a two-dimensional picture, but it represents no less a reification error. Because the model is not a literal physical layout, one is still owed an explanation of why spatial properties hold in the model – whether because of architectural constraints or by stipulation. The difference is like the difference between explaining behavior from a principle and predicting it by looking it up in a list. In the latter case no purpose is being served by calling it a mental model.

Phillips & Silverstein (P&S, 2003) propose that NMDA-receptor dysfunction may be the fundamental neurobiological mechanism underlying and associating impaired holistic perception and cognitive coordination with schizophrenic psychopathology. We discuss how the P&S hypothesis shares different aspects of the weak central coherence account of autism from both theoretical and experimental perspectives. Specifically, we believe that neither those persons with autism nor those with schizophrenia integrate visuo-perceptual information efficiently, resulting in incongruous internal representations of their external world. However, although NMDA-hypofunction may be responsible for perceptual impairments in schizophrenia and possibly autism, we suggest that it is highly unlikely that NMDA-hypofunction is specifically responsible for the autistic behavioral symptomology, as described by P&S in their target article.

Phillips & Silverstein (P&S, 2003) have proposed that NMDA-receptor hypofunction is the central reason for impaired cognitive coordination and abnormal gestalt-like perceptual processing in schizophrenia. We suggest that this model may also be applicable to non-pathological (or normal) aging given the compelling evidence of NMDA-receptor involvement during the aging process that results in age-related change in higher-level perceptual performance. Given that such deficits are present in other neurological disorders such as autism, an argument for a systematic assessment of perceptual functioning in these conditions may be posited.

Studies of aging and autism as outlined by Bertone, Mottron, & Faubert (Bertone et al.) and by Faubert & Bertone suggest that disorders of cognitive coordination involving impairments of dynamic gestalt grouping and context-sensitivity may be common to several different disorders. We agree that such studies may shed light on these processes and their neuronal bases. However, we also emphasize that dynamic grouping and context-sensitivity can fail in various ways, and that, although the underlying pathophysiology may often involve NMDA-receptor malfunction, many different malfunctions are possible, and each of these may result from any one of a number of different etiologies.

The metacognitive stance of Smith et al. (2003) risks ignoring sensory consciousness. Although Smith et al. rightly caution against the tendency to preserve the uniqueness of the human mind at all costs, their reasoned stance is undermined by a selective association of consciousness with high-level cognitive operations. Neurobiological evidence may offer a more general, and hence more inclusive, basis for the systematic study of animal consciousness.