Individualism is not inconsistent with social interaction; it is required to explain it. Social exchanges, evidenced in gaze monitoring, social referencing, emotional responses, protodeclarative and imperative pointing, pretence, play, and conversation all play a role in development, but the nature of that role is opaque without an understanding of the cognitive mechanisms on which they depend.

How can one conceive of the neuronal implementation of the processing model we proposed in our target article? In his commentary (Pulvermüller 1999, reprinted here in this issue), Pulvermüller makes various proposals concerning the underlying neural mechanisms and their potential localizations in the brain. These proposals demonstrate the compatibility of our processing model and current neuroscience. We add further evidence on details of localization based on a recent meta-analysis of neuroimaging studies of word production (Indefrey & Levelt 2000). We also express some minor disagreements with respect to Pulvermüller's interpretation of the “lemma” notion, and concerning his neural modeling of phonological code retrieval. Branigan & Pickering discuss important aspects of syntactic encoding, which was not the topic of the target article. We discuss their well-taken proposal that multiple syntactic frames for a single verb lemma are represented as independent nodes, which can be shared with other verbs, such as accounting for syntactic priming in speech production. We also discuss how, in principle, the alternative multiple-frame-multiple-lemma account can be tested empirically. The available evidence does not seem to support that account.

The interests of mother and infants do not exactly coincide. Further, infants are not merely objects of attempted control by mothers, but the sources of attempts to control what mothers do. Taking account of the ways in which this is so suggests an enriched perspective on mother-infant interaction and on the beginnings of conventionalized signaling.

This commentary challenges the argument that the diathesis for hallucinations is equivalent to that for schizophrenia. Evidence against this comes from data on the prevalence of hallucinations in schizophrenia, their nonspecificity, and their relationships with moderating variables. We also highlight, however, the manner in which the Behrendt & Young (B&Y) hypothesis extends recent neuroscientific theories of schizophrenia, and its potential treatment applications.

In the A-not-B situation children reach toward location A when the object is at location B. Researchers interpret this as an error. I question this interpretation. Reaches are inaccurate only if the intention actually is to obtain the hidden object. If this is not the goal, then reaching for A may be accurate and there may be no error to be explained.

Adopting a constructivist stance is not irreconcilable with executive function accounts of emerging social understanding. The executive function view allows for a gradual transition in theory of mind, while specifying the underlying cognitive processes that push that development forward. Executive function abilities can be seen as an important interactional component in the epistemic triangle.

Inspired by Rick Grush's emulation theory, we reinterpreted a series of our neuroimaging experiments which were intended to examine the representations of complex movement, modality-specific imagery, and supramodal imagery. The emulation theory can explain motor and cognitive activities observed in cortical motor areas, through the speculation that caudal areas relate to motor-specific imagery and rostral areas embrace an emulator for amodal imagery.

O'Brien & Opie's connectionist vehicle theory of consciousness is heavily dependent on their notion of explicitness as (1) structural and (2) necessary and sufficient for consciousness. These assumptions unnecessarily constrain their position: the authors are forced to find an intrinsic property of patterns that accounts for the distinction between conscious and unconscious states. Their candidate property, stability, does not capture this distinction. Yet, I show that we can drop assumptions (1) and (2) and still develop a vehicle theory of consciousness. This alternative is better served by models that incorporate both connectionist and symbolic representations.

I propose that hyperactivity (or increased numbers) of neurons in the brainstem reticular core promote hallucinations by excessive excitation, coupled with disinhibition, of target thalamocortical neurons. This idea stems from animal experiments using kainate-induced overexcitation of midbrain reticular neurons leading to hallucinatory-type behavior during wakefulness, as well as from data in schizophrenic patients showing an increased number of neurons in mesopontine cholinergic neurons.

Martínez-Manrique contends that we overlook a possible nonconnectionist vehicle theory of consciousness. We argue that the position he develops is better understood as a hybrid vehicle/process theory. We assess this theory and in doing so clarify the commitments of both vehicle and process theories of consciousness.

In this commentary we discuss a predictive sensorimotor illusion, the size-weight illusion, in which the smaller of two objects of equal weight is perceived as heavier. We suggest that Grush's emulation theory can explain this illusion as a mismatch between predicted and actual sensorimotor feedback, and present preliminary data suggesting that the cerebellum may be critical for implementing the emulator.

The authors' results support a functionalist conception of working memory: a manifold repertoire of schemes/schemas (long-term memory) and a small set of general-purpose “hidden operators.” Using some of these operators I define mental (i.e., endogenous) attention. Then, analyzing two of the authors' unexplained important findings, I illustrate the mental-attention model's explanatory power. Multivariate methodology that varies developmental, task differences, and individual differences is recommended.

Interpersonal understanding is rooted in social engagement. The question is: How? What features of intersubjective coordination are essential for the growth of concepts about the mind, and how does development proceed on this basis? Carpendale & Lewis (C&L) offer many telling insights, but their account begs questions about the earliest forms of self-other linkage and differentiation, especially as mediated by processes of identification.

The hypothesis that language began as a multimodal, gestural complex finds support in data from spoken languages on the connection between intonation and gesture, as well as from the process by which intonation becomes codified into grammar. Also, data from signed languages show a similar process at work, in which gestural elements become incorporated as intonation and conventionalized as grammatical markers.

My responses to the observations and criticisms of 26 commentaries focus on the coregulated and affective nature of initial mother/infant interactions, the relationship between motherese and emergent linguistic skills and its implication for hominin evolution, the plausibility of the “putting the baby down” hypothesis, and details about specific neurological substrates that may have formed the basis for the evolution of prelinguistic behaviors and, eventually, protolanguage.

Carpendale & Lewis (C&L) provide a convincing argument for how children construct social understanding through social interaction. Certainly mothers are important in family interaction; however, sibling interaction may also be key in the process of developing social understanding. In particular, the highly affective and reciprocal dynamics of the sibling relationship in both positive and conflictual interaction may be critical.

The application of evolutionary perspectives to analyzing sex differences in aggressive behavior and dominance hierarchies has been found useful in multiple areas. We draw attention to the parallel of gender differences in the worsening health status of restructuring societies. Drastic socio-economic changes are interpreted as examples of hierarchy disruption, having differential psychological and behavioral impact on women and men, and leading to different changes in health status.

Gamma rhythms are associated with external and internal sensory processing. Within the conceptual framework of “top-down” and “bottom-up” processing, this suggests that gamma represents a format common to both camps. As these oscillations facilitate communication in the temporal domain, they may represent a mechanism by which top-down and bottom-up processing can interact. A breakdown in this interaction may lead to hallucinations.

Grush makes extensive use of von Holst and Mittelstaedt's (1950) efference copy hypothesis. Although his embellishment of the model is admirably more sophisticated than that of its progenitors, I argue that it still suffers from the same conceptual limitations as entailed in its original formulation.

The commentators provide a wealth of additional neurobiological data that ought to be integrated in a comprehensive model. This response article, however, focuses on clarification of conceptual queries, thereby outlining the proposed theory of hallucinations more sharply, discussing its relationship with schizophrenia, and explaining why underconstrained thalamocortical activation may well be a candidate mechanism responsible for acute schizophrenic symptoms other than hallucinations.