Inferences made from endocasts of fossil skulls cannot provide information on the function of particular neocortical areas or the subcortical pathways to prefrontal cortex that form part of the neural substrate for speech, syntax, and certain aspects of cognition. The neural bases of syntax cannot be disassociated from “communication.” Manual motor control was probably a preadaptive factor in the evolution of humansyntactic ability, but neurophysiological data on living humans show that speech motor control and syntax are more closely linked. The evolution of fully modern speech occurred fairly recently; though Homo habilis may have had some degree of speech and syntactic ability, it was not fully modern. Stone tools are uncertain indices of language or cognition.

Whereas the λ model provides a useful technique to describe complex movements, the focus on control variables in this model limits its potential for interpreting the activity and function of many cells in motor areas of the CNS.

In my target article, I argued (1) that the relationship between neocortical size and group size in primates implies that there is a cognitive limit on the size of human groups, and (2) that time constraints forced the evolution of language as a more efficient means of bonding the large groups that humans evolved. The doubts about these claims raised by these additional commentaries largely reflect misinterpretation of my original claims.

Problems of definition and identification in the integrated evolutionary model of sociopathy are suggested by Schoenfeld's (1974) criticism of the field of race differences in intelligence. Moral judgments by those labeled primary and secondary sociopaths may offer a way to validate the assumptions of the model.

An alternative multi-joint extension to the lambda model is proposed. According to this extension, the activity of a muscle depends not only on the difference between lambda and length of that muscle, but also on the difference between lambda and length of other muscles. This 2-D extension can describe more neurophysiological experiments than the extension proposed in the target article.

This commentary confronts one of the central tenets advanced in Wilkins & Wakefield's target article: “language is unlikely to have evolved directly from communication-based precursors, nor is it likely to have been based on those structures that subserve communication.” By adopting a very narrow perspective on language, the authors have effectively limited discussion of earlier linguistic capabilities thought to be at least facilitative of, if not prerequisite to language defined as a “formal grammatical system.” An alternative conceptualization for describing semiogenesis is offered.

Psychopathy has as its central traits socialization, sensation seeking, and impulsivity. These are combined in a supertrait: Impulsive Unsocialized Sensation Seeking (ImpUSS). Secondary types are defined by combinations of ImpUSS and neuroticism or sociability. All broad personality traits have both genetic and environmental determination, and therefore different etiologies (primary as genetic, secondary as environmental) for primary and secondary sociopathy are unlikely.

I argue against the mentalist view that commonsense psychology (CSP) is about the intrinsic properties of the mind, and in particular against the notion that the evidence privately or publicly available to the CS psychologists confirms the mentalist view. I suggest that the internal phenomenology of mental attitudes merely provides access to a body of procedural knowledge, and that the propositional forms of the attitudes normally summarize extensive units of procedural knowledge.

Gopnik's argument that instead of having privileged access we must develop a theory about our minds is criticized. First, the theory metaphor is too vague, and scientific concepts of what a theory is are left unexploited. Second, the studies Gopnik interprets as showing that children must develop a theory about their mental states are also compatible with the view that children have to develop these states.

This commentary criticizes Wilkins & Wakefield's thesis that the neurological precursors of language provide a cognitive Rubicon to linguistically divide human from nonhuman primates. A causal model of their theory is presented, followed by a discussion of the relationship between brain expansion and tool use, Broca's area and the parietaloccipital-temporal junction (POT).

Recent studies lend support to the two-pathway model of the evolution of sociopathy with evidence that: 1) psychopathy (primary sociopathy) is a discrete type and 2) in general, sociopaths have relatively high levels of reproductive success. Hare's Psychopathy Checklist may provide a start for the revision of terminology that will be necessary to distinguish between primary and secondary trajectories.

Important similarities exist between the dynamical concepts implicit in Feldman & Levin's extended λ model and those basic to a dynamical systems approach. We argue that careful application of the key concepts of control and order parameters, equilibria, and stability, can relate known facts of neuromuscular processes to the observables of functional, task-specific behavior.

Examination of infant spontaneous and goal-directed arm movements supports Feldman and Levin's hypothesis of a functional hierarchy. Early infant movements are dominated by biomechanical and dynamic factors without external frames of reference. Development involves not only learning to generate these frames of reference, but also protecting the higher-level goal of the movement from internal and external perturbations.

Wilkins & Wakefield's intriguing model of language evolution is deficient in evidence of human uniqueness in metaphorical matching, amodal representation, reference, conceptual structure, hierarchical organization, linguistic comprehension, sign use, laterality, and handedness. Primates show communicative reference, laterality, and handedness, and apes in particular show hierarchical organization, conceptual structure, cross-modal abilities, sign use, and displaced reference.

Alvin Goldman (1993) presents three arguments against the psychological plausibility of representational functionalism (RF) as a theory of how subjects self-ascribe mental predicates. Goldman appears to construe RF as an account of attitude type self-ascription. His “combinatorial explosion” argument, however, proves devastating only to an implausible construal of RF as an account of attitude content self-ascription.

Given that psychophysical responses are not a function of a single property but vary with a variety of stimulus and context variables, Lockhead has little hope for laws relating behavior to the environment. However, progress can be made with tasks that manipulate multiple sources of information to test formal information-processing models.

In contrast to Lockhead's view it is argued that psychology as a genuine science must not be based on other sciences and that psychological measurements have to be validated inside psychology. It is pointed out that psychological scalings, unaffected by judgment contexts, can be obtained if the experimental setting is compatible with everyday situations.

The syntactic structures of natural languages reflect conceptual categories more directly than they reflect communicative categories. This fact supports the main premise of the target article, namely, that the most important event in language evolution was the development of a hierarchical conceptual structure.

It is argued that the equilibrium point model can lead to new insights regarding transition and stability processes in movement coordination. The role of movement control parameters on equifinality and phase-resetting is discussed; not only control but also external control parameters can affect the global dynamical regime.

I argue that the same general principles apply in ascribing mental states and their contents to self and to others. Nevertheless Goldman is right that there is such a thing as FPA (First Person Authority). But Gopnik is right that FPA cannot be explained by reference to a special way of knowing or a special land of knowledge.