Barsalou's theory of perceptual symbol systems is considered from a metacognitive perspective. Two examples are discussed in terms of the proposed perceptual symbol theory. First, recent results in research on feeling-of-knowing judgement are used to argue for a representation of familiarity with input cues. This representation should support implicit memory. Second, the ability of maintaining a theory of other people's beliefs (theory of mind) is considered and it is suggested that a purely simulation-based view is insufficient to explain the available evidence. Both examples characterize areas where Barsalou's theory would benefit from additional detail.

Pylyshyn argues that early vision is cognitively impenetrable, and therefore – contrary to knowledge-based theories of perception – that perception is noncontinuous with cognition. Those processes that are included in “early vision,” however, represent at best only one component of perception, and it is important that it is not the component with which most knowledge-based theories are concerned. Pylyshyn's analysis should be taken as a possible source of refinement of knowledge-based theories of perception, rather than as a condemnation of them.

This commentary discusses how Dienes & Perner's theory of implicit and explicit knowledge applies to memory research. As currently formulated, their theory does seem to account simultaneously for population dissociations and dissociations between conceptual and perceptual priming tasks. In addition, the specification of four distinct memorial states (correlated with different recognition test responses) faces important methodological challenges.

Palmer's “isomorphism constraint” may be interpreted as a claim about (1) what can be known with certainty, or (2) what can be detected, or (3) what beliefs can be justified on the basis of a certain kind of scientific knowledge. I argue that his claim is valid if interpreted in one of the first two ways, but invalid if interpreted in the third way.

The controversial status of goluboi as a basic color term is discussed. Fuzzy logic alone cannot reliably attribute basic status to goluboi. Recent linguistic studies support a single basic blue category. Psychophysical data on color-space distances and color naming are currently ambiguous in this regard.

The thesis that women will be more intent on staying alive fails to take into account that current strategies are those of the winners in the evolutionary race. Moreover, because like tends to mate with like, risk taking will be averaged out between the sexes. Finally, Campbell's narrow view of parental investment fails to acknowledge the indirect contributions of males.

The commentaries provide a multitude of perspectives on the theory of lexical access presented in our target article. We respond, on the one hand, to criticisms that concern the embeddings of our model in the larger theoretical frameworks of human performance and of a speaker's multiword sentence and discourse generation. These embeddings, we argue, are either already there or naturally forgeable. On the other hand, we reply to a host of theory-internal issues concerning the abstract properties of our feedforward spreading activation model, which functions without the usual cascading, feedback, and inhibitory connections. These issues also concern the concrete stratification in terms of lexical concepts, syntactic lemmas, and morphophonology. Our response stresses the parsimony of our modeling in the light of its substantial empirical coverage. We elaborate its usefulness for neuroimaging and aphasiology and suggest further cross-linguistic extensions of the model.

Pylyshyn's model of visual perception leads to problems in understanding the nature of perceptual experience. The cause of the problems is an underlying lack of clarity about the relation between the operation of the subpersonal vision module and visual perception at the level of the subject or person.

Barsalou's hypothesis that mental representations are constructed by selecting parts of percepts encounters the same difficulties as other empiricist theories: They cannot explain concepts for which instances do not share perceptible features (e.g., furniture) or for which there are no relevant percepts (e.g., the end of time). Barsalou's attempt to reduce falsity to failed pattern matching is an elementary error, and the generativity of his simulators cannot be attained without nonterminal symbols. There is not now, and there never was, any reason to be interested in empiricist theories of knowledge. Abstraction is a fundamental aspect of human cognition.

We argue that Dienes & Perner's (D&P's) proposal needs to specify independent criteria when a subject explicitly represents factuality. This task is complicated by the fact that people typically “tacitly” believe that each of their beliefs is a fact. This problem does not arise for comparative evidence on monkeys, for they presumably lack the capacity to represent factuality explicitly. D&P suggest that explicit visual processing and declarative memory depend on explicit representations of factuality, whereas the analogous implicit processes do not require such representations. Many of the implicit/explicit findings are also found in monkeys, however, and D&P's account needs to explain this striking parallel.

Basic processes of perception should be cognitively impenetrable so that they are not prey to momentary changes of belief. That said, how does low level vision interact with knowledge to allow recognition? Much more needs to be known about the products of low level vision than that they represent the geometric layout of the world.

In restricting his analysis to the causal relations of functionalism, on the one hand, and the neurophysiological realizers of biology, on the other, Palmer has overlooked an alternative conception of the relationship between color experience and the brain – one that liberalizes the relation between mental phenomena and their physical implementation, without generating functionalism's counter-intuitive consequences. In this commentary we rely on Palmer's earlier work (especially from 1978) to tease out this alternative.

Distinguishing explicit from implicit knowledge on the basis of the active representation of certain propositional attitudes fails to provide an explanation for dissociations in learning performance under implicit and explicit conditions. This suggests an account of implicit and explicit knowledge grounded in the presence of multiple learning mechanisms, and multiple brain systems more generally. A rough outline of a connectionist account of this kind is provided.

We propose a way in which Barsalou could strengthen his position and at the same time make a considerable dent in the category/abstraction problem (that he suggests remains unsolved). There exists a class of connectionist models that solves this problem parsimoniously and provides a mechanistic underpinning for the promising high-level architecture he proposes.

Human mating and parenting are more complex than has been implied by many evolutionarily based theories of sex differences. While focusing on sex differences might shed some light on the evolution of mating and parenting, this level of analysis is rather imprecise. More important, it ignores several ecological variables that should have influenced mating/parenting decisions and behaviors in both sexes.

This target article discusses the verbal working memory system used in sentence comprehension. We review the concept of working memory as a short-duration system in which small amounts of information are simultaneously stored and manipulated in the service of accomplishing a task. We summarize the argument that syntactic processing in sentence comprehension requires such a storage and computational system. We then ask whether the working memory system used in syntactic processing is the same as that used in verbally mediated tasks that involve conscious controlled processing. Evidence is brought to bear from various sources: the relationship between individual differences in working memory and individual differences in the efficiency of syntactic processing; the effect of concurrent verbal memory load on syntactic processing; and syntactic processing in patients with poor short-term memory, patients with poor working memory, and patients with aphasia. Experimental results from these normal subjects and patients with various brain lesions converge on the conclusion that there is a specialization in the verbal working memory system for assigning the syntactic structure of a sentence and using that structure in determining sentence meaning that is separate from the working memory system underlying the use of sentence meaning to accomplish other functions. We present a theory of the divisions of the verbal working memory system and suggestions regarding its neural basis.

I criticize three claims concerning simulators: (1) That a simulator provides the best-fitting simulation of the perceptual impression one has of an object does not guarantee, pace Barsalou, that the object belongs to the simulator's category. (2) The people described by Barsalou do not acquire a concept of truth because they are not sensitive about the potential inadequacy of their sense impressions. (3) Simulator update prevents Barsalou's way of individuating concepts (i.e., identifying them with simulators) from solving the problem of intra-personal concept stability because to update a simulator is to change its content, and concepts with different contents are distinct.

Dienes & Perner offer us a theory of explicit and implicit knowledge that promises to systematise a large and diverse body of research in cognitive psychology. Their advertised strategy is to unpack this distinction in terms of explicit and implicit representation. But when one digs deeper one finds the “Higher-Order Thought” theory of consciousness doing much of the work. This reduces both the plausibility and usefulness of their account. We think their strategy is broadly correct, but that consensus on the explicit/implicit knowledge distinction is still a fair way off.

In their competition for higher-status men, women with higher socioeconomic status use indirect forms of aggression (ridicule and gossip) to derogate lower-status female competitors and the men who date them. Women's greater tendency to excuse their aggression is arguably a cultural enhancement of an evolutionarily based sex difference and not solely a cultural construction imposed by patriarchy.

Palmer's principled distinction between first-person experience and scientific access is called into question. First, complete color transformations of experience and memory may be undetectable even from the first-person perspective. Second, transformations of (say) pain experiences seem to be intrinsically connected to certain effects, thus giving science access to these experiences, in principle. Evidence from pain research and emotional psychology indicates that further progress can be made.