Pylyshyn circumvents an even more fundamental question: Are the mechanisms of visual perception accessible to the theoretician? Neurophysiology, computer modeling, and psychophysics, as well as his definitions of visual phenomena suggest that he has asked an unanswerable question.

In this Response, I defend the notion of intrinsic qualities of experience, discuss the distinction between relational experience and relational structure, clarify the difference between narrow and broad interpretations of color experience, argue against externalist approaches to color experience, defend the concept of isomorphism as a limitation in understanding color experiences, examine critiques of the color machine and color room arguments, and counter objections to within-subject experiments based on memory limitations.

Following much work in linguistic theory, it is hypothesized that the language faculty has a modular structure and consists of two basic components, a lexicon of (structured) entries and a computational system of combinatorial operations to form larger linguistic expressions from lexical entries. This target article provides evidence for the dual nature of the language faculty by describing recent results of a multidisciplinary investigation of German inflection. We have examined: (1) its linguistic representation, focussing on noun plurals and verb inflection (participles), (2) processes involved in the way adults produce and comprehend inflected words, (3) brain potentials generated during the processing of inflected words, and (4) the way children acquire and use inflection. It will be shown that the evidence from all these sources converges and supports the distinction between lexical entries and combinatorial operations.

Our experimental results indicate that adults have access to two distinct processing routes, one accessing (irregularly) inflected entries from the mental lexicon and another involving morphological decomposition of (regularly) inflected words into stem+affix representations. These two processing routes correspond to the dual structure of the linguistic system. Results from event-related potentials confirm this linguistic distinction at the level of brain structures. In children's language, we have also found these two processes to be clearly dissociated; regular and irregular inflection are used under different circumstances, and the constraints under which children apply them are identical to those of the adult linguistic system.

Our findings will be explained in terms of a linguistic model that maintains the distinction between the lexicon and the computational system but replaces the traditional view of the lexicon as a simple list of idiosyncrasies with the notion of internally structured lexical representations.

The Findlay-Walker model does not consider saccades generated by auditory targets or nontargets (distractors), or by bimodal stimulation. Empirical results suggest that the effects of auditory stimulation cannot easily be incorporated into the model, neither in the WHEN nor in the WHERE system. A two-stage model by Colonius and Arndt gives a quantitative account of the facilitative effects of auditory distractors on saccadic latencies toward visual targets.

It is argued that the alleged cases of cognitive penetration of visual modules actually arise from the integration of information among different modules. This would reflect a general computational strategy according to which constraints to a particular module would be provided by information coming from different modules. Examples are provided from the integration of stereopsis and occlusion and from computation of motion direction.

The correlative coactivation of sensory inputs, Hebb's “second rule,” probably plays a critical role in the formation of word representations in the neocortex. It is essential to the acquisition of word meaning. The acquisition of semantic memory is inseparable from that of individual memory, and therefore the two probably share the same neural connective substrate. Thus, “content” words are represented mainly in postrolandic cortex, where individual perceptual memories are also represented, whereas “action” words are represented in frontal cortex, with executive memories. The activation of a memory network may not necessarily entail the high-frequency oscillatory firing of its cells, though reverberation remains a plausible mechanism of short-term memory.

Limitations of Dienes & Perner's (D&P's) theory are traced to the assumption that the higher-order thought (HOT) theory of consciousness is true. D&P claim that 18-month-old children are capable of explicitly representing factuality, from which it follows (on D&P's theory) that they are capable of explicitly representing content, attitude, and self. D&P then attempt to explain 3-year-olds' failures on tests of voluntary control such as the dimensional change card sort by suggesting that at this age children cannot represent content and attitude explicitly. We provide a better levels-of-consciousness account for age-related abulic dissociations between knowledge and action.

Scalp-recorded event-related potential (ERP) measures of reading and listening have been proved more sensitive to the time course of syntactic processing than the chronometric and behavioral data described by Caplan & Waters. ERP studies using sentences containing relative clauses indicate that there are individual differences in syntactic processing that appear at the earliest theoretically relevant time points and are attributable to working memory operations.

Pylyshyn's effort in establishing the cognitive impenetrability of early vision is welcome. However, his view about the role of attention in early vision seems to be oversimplified. The allocation of focal attention manifests its effect among multiple stages in the early vision system, it is not just confined to the input and the output levels.

Dienes & Perner argue that the explicit representation of an individual to which a property is attributed requires explicit representation of the attributed property. The reasons for this conclusion are similar to the reasons why another of their conclusions may be considered suspect: A property may be explicit without an explicit representation of an individual or the predication of the property to an individual. We question the latter conclusion and draw connections to neurophysiological and cognitive evidence.

Pulvermüller traces the differences in brain activity associated with function and content words. The model considers words displayed primarily in isolation. Research on letter detection suggests that what distinguishes function from content words are their roles in text. Hence a model that fails to consider context effects on the processing of words provides an insufficient accounting of word representation in the brain.

A promising approach to more refined models consistent with the Caplan & Waters hypothesis is based on similarity-based interference, a general principle that applies across working memory domains. This may explain both the fine details of syntactic working memory phenomena and the gross fractionation for which Caplan & Waters have found evidence. Detailed models of syntactic processing that embody similarity-based interference fare well cross-linguistically.

Patients with schizophrenia have an impairment in the inhibition of reflexive saccades, as a consequence of a functional impairment of the prefrontal cortex, which has not yet been encapsulated in terms of a formal model. A number of novel and testable hypotheses can be generated from the framework proposed by Findlay & Walker that will stimulate further research. Their framework therefore marks an important step in the development of a comprehensive functional model of saccadic eye movements. Further advances will be assisted by (1) a recognition of important distinctions in the executive control of volitional saccades and (2) addressing the capacity for cross-model integration of spatial information in the generation of the spatial properties of saccadic eye movements.

We discuss other recent studies on the acquisition of the German plural that do not support the dual-mechanism model. The attested overgeneralizations are not by default only, nor completely random, but predictable from subregularities based on the grammatical gender and the phonology of the noun. In addition, the dual-mechanism model creates a number of problems for acquisition (theory) rather than solving existing ones.

Although the working memory capacity involved in syntactic processing may be separate from the capacity involved in word list recall, other aspects of initial sentence interpretation appear to depend on some of the same capacities tapped by span tasks. Specifically, there appears to a capacity for lexical–semantic retention involved in both sentence comprehension and span measures.

We offer an ecological (Gibsonian) alternative to cognitive (im)penetrability. Whereas Pylyshyn explains cognitive (im)penetrability by focusing solely on computations carried out by the nervous system, according to the ecological approach the perceiver as a knowing agent influences the entire animal-environmental system: in the determination of what constitutes the environment (affordances), what constitutes information, what information is detected and, thus, what is perceived.

Removing attention from the saccade generation system should also remove the paradoxical loops that can occur with attention terminology. At least one such loop is still apparent in the current model, however. The benefits of an attention-free approach are assessed through comparison with a recent theory of attention (Logan 1996).

In this response, we start from first principles, building up our theory to show more precisely what assumptions we do and do not make about the representational nature of implicit and explicit knowledge (in contrast to the target article, where we started our exposition with a description of a fully fledged representational theory of knowledge (RTK). Along the way, we indicate how our analysis does not rely on linguistic representations but it implies that implicit knowledge is causally efficacious; we discuss the relationship between property structure implicitness and conceptual and nonconceptual content; then we consider the factual, fictional, and functional uses of representations and how we go from there to consciousness. Having shown how the basic theory deals with foundational criticisms, we indicate how the theory can elucidate issues that commentators raised in the particular application areas of explicitation, voluntary control, visual perception, memory, development (with discussion on infancy, theory of mind [TOM] and executive control, gestures), and finally models of learning.

Pulvermüller's Hebbian model implies that an impairment in the word form system will affect phonological articulation and phonological comprehension, because there is only a single representation. Clinical evidence from patients with word-form deafness demonstrates a dissociation between input and output phonologies. These data suggest that auditory comprehension and articulatory production depend on discrete phonological representations localized in different cortical networks.

Clahsen's claim that output forms of productive processes are never listed in the lexicon is a consequence of the rule/list fallacy, empirically incorrect, and not necessary for the hypothesis that the human language faculty has a dual structure, that is, a lexicon and a set of rules.