One of the main aspects of a neurobiological theory of language is the problem of meaning (or semantic content) in the brain. A full explanation of meaning requires a combined approach to semantic typing and the semantic success of cerebral states or processes. Pulvermüller presents his Hebbian model of language in the brain (HML) as an account of semantic success. If his proposal turns out to be viable, however, it may also promote a theory of semantic typing.

The target article argues for the modularity of language interpretive processes without the usual criterion that a module be informationally encapsulated. It is the encapsulation criterion, however, that gives modularity most of its testability. Without the criterion of encapsulation, testing whether relatively automatic comprehension processes use their own unique resource is a very tricky matter.

Perirhinal cortex contributes to judgements about stimulus familiarity, but its role is far greater than this. Impairments on tasks that do not involve familiarity judgements attest to the fact that perirhinal cortex is involved in the greater role of knowing about objects, including, but not limited to, their relative familiarity.

Empirical evidence suggests that high frequency electrographic activity is involved in active representation of meaningful entities in the cortex. Theoretical work suggests that distributed cell assemblies also represent meaningful entities. However, we are still some way from understanding how these two are related. This commentary also makes suggestions for further investigation of the neural basis of language at the level of both words and sentence planning.

Clahsen reports the results from two sets of word-recognition experiments with adult native speakers of German supporting the notion that the processing of regular (or default) inflection differs from the processing of irregular inflection. My commentary points to shortcomings in stimulus selection and inconsistencies in the pattern of results, revealing that the empirical support for the proposed dual mechanism is much weaker than Clahsen suggests.

I argue that Gold & Stoljar's “trivial neuron doctrine” is not in fact trivial. Many familiar positions in the philosophy of mind run afoul of it, and it is unclear that even those whom Gold & Stoljar identify as adherents of the trivial neuron doctrine can be comfortably described as such.

In the model proposed by Findlay & Walker, the programming of saccadic eye movements is achieved by two parallel processes, one dedicated to the coding of saccade metrics (Where) and the other controlling saccade initiation (When). One outcome of the “winner-take-all” characteristics of the salience map, the main node of the model, is an independence between the metrics and the latency of saccades. We report on some observations, made in the head-unrestrained cat under pathological conditions, of a correlation between accuracy and latency of saccadic gaze shifts. To account for such a correlation, the link between metrics specification (Where) and saccade triggering (When) should be amended in the model.

Caplan & Waters argue that the processing resources used for sentence comprehension are not drawn from an undifferentiated verbal working memory resource. This commentary cites data from normal aging to support this position. Still lacking in theory development is a specification of the transient memory representations necessary for interpretive and post-interpretive operations.

The trivial neuron doctrine (TND) holds that psychology merely depends on neurobiology. The radical neuron doctrine (RND) goes further and claims that psychology is superfluous in that neuroscience can “replace it.” Popular among RND notions of “replacement” is “reduction,” and in our commentary we challenge Gold & Stoljar (G&S) to make clear their distinction between merely depends on (TND) and is reducible to (RND). G&S give us a TND–RND distinction that is a distinction without a difference; a defensible TND–RND distinction must have a metaphysical basis. We suggest a denial of compositionalism as such a basis.

Commentaries on our target article raise further questions about the validity of an undifferentiated central executive that supplies resources to all verbal tasks. Working memory tasks are more likely to measure divided attention capacities and the efficiency of performing tasks within specific domains than a shared resource pool. In our response to the commentaries, we review and further expand upon empirical findings that relate performance on working memory tasks to sentence processing, concluding that our view that the two are not strongly related remains viable in light of the material presented in the commentaries. We suggest that a productive research enterprise would be to develop the concept of working memory as a pool of resources in relation to specific tasks.

Experiments using a modified gap paradigm, where regular trials are intermingled with catch trials (trials without saccade target), demonstrate that the relative frequency of express versus regular saccades distinctly depends on catch trial frequency. More specifically, it has been shown that the probability of an express saccade depends stochastically on the type of the preceding trial, that is, on the sequence of stimuli. We discuss whether such contextual effects can be accommodated within the framework of Findlay & Walker's model.

The received view in historical linguistics is that there is always an inverse relation between token frequency and likelihood of analogical change. I have found evidence, however, of a sharp difference in frequency effects between regularization and nonregularizing analogical change. I argue that this difference can easily be accounted for by dual-mechanism models of inflection but is very problematic for pure associative-memory models.

Pulvermüller advocates an experimental design in which well-matched tokens from various word categories are presented in list form to subjects making rapid lexical decisions about these stimuli. Implicit in this paradigm are several problematic assumptions. We conclude that such experiments are not likely to tell us much about the biological bases of human language.

This commentary attempts to reconcile the predictions of Aggleton & Brown's theoretical framework with previous findings obtained from experimental tests of laboratory animals with selective hippocampal lesions. Adopting a convergent operations approach, the predictions of the model are also related to human neuroimaging data and to other complementary research perspectives (cognitive, computational, psychopharmacological).

When cognitive scientists apply computational theory to the problem of phenomenal consciousness, as many have been doing recently, there are two fundamentally distinct approaches available. Consciousness is to be explained either in terms of the nature of the representational vehicles the brain deploys or in terms of the computational processes defined over these vehicles. We call versions of these two approaches vehicle and process theories of consciousness, respectively. However, although there may be space for vehicle theories of consciousness in cognitive science, they are relatively rare. This is because of the influence exerted, on the one hand, by a large body of research that purports to show that the explicit representation of information in the brain and conscious experience are dissociable, and on the other, by the classical computational theory of mind – the theory that takes human cognition to be a species of symbol manipulation. Two recent developments in cognitive science combine to suggest that a reappraisal of this situation is in order. First, a number of theorists have recently been highly critical of the experimental methodologies used in the dissociation studies – so critical, in fact, that it is no longer reasonable to assume that the dissociability of conscious experience and explicit representation has been adequately demonstrated. Second, classicism, as a theory of human cognition, is no longer as dominant in cognitive science as it once was. It now has a lively competitor in the form of connectionism; and connectionism, unlike classicism, does have the computational resources to support a robust vehicle theory of consciousness. In this target article we develop and defend this connectionist vehicle theory of consciousness. It takes the form of the following simple empirical hypothesis: phenomenal experience consists of the explicit representation of information in neurally realized parallel distributed processing (PDP) networks. This hypothesis leads us to reassess some common wisdom about consciousness, but, we argue, in fruitful and ultimately plausible ways.

In this commentary we describe findings in normal human subjects and in patients with visual hemineglect that support the importance of higher-level influences on saccade generation during visual exploration. As the duration of fixations increases with increases in the cognitive demand of the task, the timing of exploratory saccades is controlled more by centers of cognitive and perceptual processing at levels 4 and 5 than by reflex-like automatic processes at level 3. In line with this, unilateral frontal eye field lesions impair systematic, intentional saccadic exploration of visual scenes, causing prolonged fixations and contralesional hemineglect, but leave visually triggered reflexive saccades largely intact.

We applaud Aggleton & Brown's affirmation of limbic diencephalic-hippocampal interaction as a key memory substrate. However, we do not agree with a thesis of diencephalic-hippocampal strict dedication to episodic memory. Instead, this circuitry supports the production of context-specific patterns of activation that subserve retrieval for a broad class of memory phenomena, including goal-directed instrumental behavior of animals and episodic memory of humans.

The history of the natural sciences repeatedly shows that the unification of a higher level theory with a lower level theory by reduction does not eliminate the need for the higher level theory nor preclude its further development, leading to changes in the understanding of the lower level. The radical neuron doctrine proposes that the future science of psychology or linguistics will derive principally from the evolution of understanding at the neural level and not from current theories based on the observation of behavior. It is far more likely that the two bodies of theory will coevolve in semiautonomous fashion.

Clahsen's characterization of nondefault inflection as based exclusively on lexical entries does not capture the full range of empirical data on German inflection. In the verb system differential effects of lexical frequency seem to be input-related rather than affecting morphological production. In the noun system, the generalization properties of -n and -e plurals exceed mere analogy-based productivity.

We raise the possibility that the roles words typically play in sentence context, rather than their motor or visual associations, determine the organization of language in the brain. We also discuss time-sensitive functional imaging approaches that allow experimentation both on isolated words and connected language.