Understanding how conceptual structures inform stone tool production and use would help us resolve the issue of a pongid-hominid dichotomy in brain organisation and cognitive ability. Evidence from ideational apraxia suggests that the planning of linguistic and manipulative behaviours is not colocalized in homologous circuits. An alternative account in terms of the evolutionary expansion of the whole prefrontal-premotor area may be more plausible.

My target article did not attribute a pervasive ontological significance to phenomenology, so it escapes Bogdan's “epistemological illusion.” Pust correctly pinpoints an ambiguity between contentinclusive and content-exclusive forms of folk functionalism. Contrary to Fodor, however, only the former is plausible, and hence my third argument against functionalism remains a threat. Van Brakel's charity approach to first-person authority cannot deal with authority vis-a-vis sensations, and it has some extremely odd consequences.

In his target article Lockhead calls attention to numerous complications that prevent a valid straightforward or Fechnerian interpretation of psychophysical data. Here I describe three additional sources of bias, all involving the influence of stimuli presented before the start of an investigation.

The following questions are discussed: (1) Who determines the nature of “control variables”? (2) Is the “positional monopoly” healthy? (3) Does a descending command alter reflex threshold alone without eoncomitantly altering stiffness? (4) How does the CNS deal with history-dependent effects? (5) Should we abandon the idea that the CNS controls classical Newtonian variables such as muscle length?

A key feature of the lambda model is the hypothesis of a local spring-like muscle-reflex system defined by a central control variable that has units of position. This is intriguing, especially for a study of postural stability in large-scale systems, but it has limited direct application to skilled everyday movements. If movement is considered as a goal-directed, neuro-optimization problem, however, the availability of lambda-like peripheral models (vs. conventional musculoskeletal models) deserves exploration.

In this response various possible objections to the critique of first-person-authority in Gopnik (1993), are considered. The heart of all three objections is that “beliefs” and other notions of commonsense psychology should not be construed as attempts to describe the functional character of our minds. Rather, they are 1) an evolutionarily determined technique for dealing with our conspecifics (Bogdan) or 2) the result of interpretation (Van Brakel) or 3) self-constitutive entities which exist only when we have the concept of their existence (Greve and Buchner). While the word belief might be construed in all these ways, they do not correspond either to the construals of our commonsense psychology or of a scientific psychology.

Wilkins & Wakefield are clearly right to separate linguistic capacity from communicative ability, if only because other animal species have one without the other. But I question the abruptness of the demarcation they make between a period when hominids evolved enriched conceptual representation for other reasons entirely, and a subsequent later stage when language use became an adaptation.

Psychophysical scales can be constructed under suitable restrictions from appropriate data, but they still do not justify privileged internal sensations.

In terms of physics, mass is the fixed attribute of an object while weight varies with the accelerative force. Neither weight nor mass are simple sensory stimuli as both involve the integration of sensory and motor information with higher cognitive processes. Studies of apparent heaviness yield only vague information about sensorimotor mechanisms.

Three issues related to Feldman and Levin's treatment of biological variability are discussed. We question the usefulness of the indirect component of δλ. We suggest that trade-offs between speed and accuracy in aimed movements support identification of δλ, rather than λ, as a control variable. We take issue with the authors' proposal for resolving redundancy in multi-joint movements, given recent data.

Wilkins & Wakefield's identification of anatomical features in the Koobi Fora endocast, which may be thought to carry some functional significance in relation to organization for language, raises fundamental problems of method: attention is drawn to some limitations of the evidence, of endocasts and of the neuroanatomical map used to interpret them.

This response clarifies the nature of reappropriation and the definition of language. It explicates the relationship between neural systems and language and between homology and evolutionary gradualism. Through a review of ape capacities in the realms of language and tool use, it distinguishes human language acquisition from nonhuman learning. Finally, it suggests the appropriate sorts of evidence on which to base further evolutionary arguments relevant to the origins of language.

Understanding of the λ model has greatly increased in recent years as evidenced by most of the commentaries. Some commentators underscored the potential of the model to integrate aspects of different sensorimotor systems in the production of movement. Other commentators focused on not-yet-fully-developed parts of the model. A few persisted in misunderstanding some of its basic concepts, and on these grounds they reject it. In responding to commentaries we continue to elaborate on some fundamental points of the model, especially control variables, the idea of movement production by shifting the positional frame of reference and the hypothesis of biomechanical correspondence in motor control. We also continue to develop our ideas on the intrinsic generation of the frame of reference associated with external space and utilized for the control of arm movement and locomotion. The dynamic principles underlying the model are discussed in light of the dynamical systems approach.

People cannot make independent judgements of stimulus attributes and so “it is necessary to theorize in terms of stimulus structures” (Lockhead 1992, p. 551) rather than in terms of stimulus features. The new commentaries here further this statement and also support the observations in the target article that psychophysical scaling methods allow us to measure (1) how context determines judgments and (2) what people remember about prior stimuli.

The notion of “multiple drafts” is one that has attracted the attention of researchers working within the “microgenetic” framework to perception and cognition, deriving from the work of Heinz Werner (1948). Dennett and Kinsboume's (1992) position can be further explored with reference to this earlier literature. The present commentary attempts to ground the D&K model within this larger theoretical debate.

Searle (1990) argues that unconscious intrinsic intentional states must be accessible to consciousness because (1) all intrinsic intentional states have aspectual shape, the “ontology” of which cannot be explained in a third-person (e.g., neurophysiological) vocabulary, and (2) ontologically, unconscious mental states are neurophysiological processes. This argument confuses three senses of “ontology,” namely, factuality, individuative properties, and phenomenological presence.