The idea that experience is essentially subjective rather than of the real world is paradoxical and deeply flawed. The external world is, much more than a mere constraint, essential to meaningfully describe experience and neural activity. This is illustrated by an analysis of the phenomenology of veridical perception and by the study of experience in psychopathology by the Experience Sampling Method (ESM).

Lachman claims that the Dynamical Hypothesis (DH) is “untenable.” His own position is a version of the “The DH is epistemological, not ontological,” objection to the target article, which is dealt with in section R2.3 of my original response (van Gelder 1998r). Additional objections are that the coverage of the hypothesis is “vast” and that the DH presupposes we have reached the end point of scientific theorizing. Indeed, the DH is very broad, but it does not presuppose that science has ended; that's why we call it a “hypothesis.”

Artificial neural networks have weaknesses as models of cognition. A conventional neural network has limitations of computational power. The localist representation is at least equal to its competition. We contend that locally connected neural networks are perfectly capable of storing and retrieving the individual features, but the process of reconstruction must be otherwise explained. We support the localist position but propose a “hybrid” model that can begin to explain cognition in anatomically plausible terms.

The general applicability of forward models in brain function has previously been recognized. Grush's contribution centers largely on broadening the extent and scope of forward models. However, in his effort to expand and generalize, important distinctions may have been overlooked. A better grounding in the underlying physiology would have helped to illuminate such valuable differences and similarities.

Page is to be congratulated for challenging some misconceptions about neural representation. However, his target article, and the commentaries to it, highlight that the terms “local” and “distributed” are open to misinterpretation. These terms provide a poor description of neural coding strategies and a better taxonomy might resolve some of the issues.

We can live in fantasy only if we survive in reality. Visual experience that carries information about the real world – that is, normal perception – serves that goal. Normal perception is not merely constrained hallucination, and it can usually be distinguished from internally generated images, with which it is rarely confused. Modulatory processes, such as attention, do indeed affect most levels of perceptual processing, but they do so without invalidating the transmission of the signals that they modulate.

Two arguments are critiqued here. The first is that hominin mothers “parked” their offspring; the evidence does not support that position. The second is that motherese developed to control the behavior of nonambulatory infants. However, Falk's case is stronger if we apply it to children who are already walking and more likely to be influenced by verbal information.

I focus on the distinction between sensation and perception. Perceptions contain additional information that is useful for interpreting sensations. Following Grush, I propose that emulators can be seen as containing (or creating) hidden variables that generate perceptions from sensations. Such hidden variables could be used to explain further cognitive phenomena, for example, causal reasoning.

Levelt, Roelofs, & Meyer (henceforth Levelt et al. 1999) propose a model of production incorporating a lemma stratum, which is concerned with the syntactic characteristics of lexical entries. We suggest that syntactic priming experiments provide evidence about how such syntactic information is represented, and that this evidence can be used to extend Levelt et al.'s model. Evidence from syntactic priming experiments also supports Levelt et al.'s conjecture that the lemma stratum is shared between the production and comprehension systems.

It is argued that constructionist theory provides only a partial account of how secure attachment leads to better social understanding. In addition to cooperative parent-child relations, the more efficient arousal and affect regulation system of secure infants, and developmental moderators of the processes of imitation, may play a part in explaining the association and offer clues as to how effective social understanding is generally acquired.

Behrendt & Young's (B&Y's) theory offers a potentially important perspective on the neurobiology of schizophrenia, but it remains incomplete. In addition to bottom-up contributions, such as those associated with disturbances in sensory constraints on cognitive processes, a comprehensive model requires the integration of the consequences of abnormal top-down modulation of input processing for the evolution of “underconstrained” perceptions. Dysfunctional cholinergic modulation of input functions represents a necessary mechanism for the generation of false perceptions.

The following questions are addressed concerning how a theory of lexical access can be realized in the brain: (1) Can a brainlike device function without inhibitory mechanisms? (2) Where in the brain can one expect to find processes underlying access to word semantics, syntactic word properties, phonological word forms, and their phonetic gestures? (3) If large neuron ensembles are the basis of such processes, how can one expect these populations to be connected? (4) In particular, how could one-way, reciprocal, and numbered connections be realized? and, (5) How can a neuroscientific approach for multiple access to the same word in the course of the production of a sentence?

We briefly address three issues that might be important to evaluate the validity of the “emulation theory”: (1) Does it really say something new? (2) Are similar processes engaged in action, imagery, and perception? (3) Does a brain amodal emulator exist?

Two meta-analyses of pharmacological research are presented, demonstrating that psychoactive drugs have consistent effects on EEG and sleep outside of their effects on REM sleep, and demonstrating that drugs other than those affecting sleep neurotransmitter systems and REM sleep can also alter reported nightmare occurrence. These data suggest that the neurobiology data terrain outside activation-synthesis may include sleep and dream electrophysiology, cognitive reports of dreaming, effects of alterations in consciousness on dreaming, immunology and host defense, and clinical therapies for sleep disorders.

Theories that propose a modular basis for developing a “theory of mind” have no problem accommodating social interaction or social environment factors into either the learning process, or into the genotypes underlying the growth of the neurocognitive modules. Instead, they can offer models which constrain and hence explain the mechanisms through which variations in social interaction affect development. Cognitive models of both competence and performance are critical to evaluating the basis of correlations between variations in social interaction and performance on mental state reasoning tasks.

We believe that “caching” a baby would have been too great a danger in human prehistory, and thus could not serve as the context for prelinguistic vocalization. Rather, infants were most likely carried at all times. Thus, the question arises of why the cry of an infant is such a loud vocalization.

The model and framework presented in the target article by Thelen et al. is an interesting effort that is able to account for the contextual variability in the A-not-B performance of 7–12-month-old infants. In the process of developing their framework, the authors discounted the concept of object as a useful notion in discussions of A-not-B performance. For Piaget and other developmentalists, the main evidence for the acquisition of the concept of object was the disappearance of A-not-B errors after age 12 months. However, the Thelen et al. model makes predictions of A-not-B outcomes over a much shorter, trial-to-trial time scale. Given the mismatch in the time scales over which analyses in the two approaches have been based, we wonder if the challenge to the concept of object has been misplaced.

The Kalman filtering technique is considered as a part of concurrent data-processing techniques also related to detection, parameter evaluation, and identification. The adaptive properties of the filter are discussed as being related to symmetrical brain structures.

Falk's paper provides a nice cross-species perspective and an interesting background to formulate a theory of the evolution of human language. However, the author does not provide a complete overview and analysis of the origins of language and takes for granted the “continuity hypothesis.” Also her “infant parking theory” is questionable, as it is not well supported by observations.

Behrendt & Young (B&Y) propose an explanation for schizophrenia in terms of a cortical default in the interaction between consciousness and cognition. However, schizophrenia more likely involves miscommunication between subcortical and cortical affective circuits in the brain, a default in the interaction between consciousness and emotion. The typical “affective” nature of hallucinations in schizophrenia provides compelling evidence for subcortical involvement.