The model presented in the target article is biased towards a cognitive-symbolic understanding of language, thus ignoring its other important aspects. Possible relationships of this cognitive-symbolic subsystem to pragmatics and prosody of language are discussed in the first part of the commentary. In the second part, the issue of a purely social versus biological mechanisms for transition from protolanguage to properly language is considered.

Recent research on visual mental imagery plays an important role for the study of visual hallucinations. Not only are mental images involved in various cognitive processes, but they also share many processes with visual perception. However, we rarely confuse mental images with percepts, and recent neuroimaging studies shed light on the mechanisms that are differently activated in imagery and perception.

multiple endogenous and exogenous prenatal influences interact to form a system that induces the development of individual lateralization across a range of perceptual and motor abilities in precocial birds. as these influences are nearly invariant for all species members, they produce a phylogenetic influence that creates high levels of population laterality and social cohesion in the postnatal state.

The key weakness of the proposed distinction between rules and similarity is that it effectively converts what was previously seen as a consequence of rule or similarity-based processing, into a definition of rule and similarity themselves – evidence is elevated into a conceptual distinction. This conflicts with fundamental intuitions about processes and erodes the relevance of the debate across cognitive science.

sagvolden, johansen, aase, and russell (sagvolden et al.) examine attention-deficit/hyperactivity disorder (adhd) at levels of analysis ranging from neurotransmitters to behavior. at the behavioral level they attribute aspects of adhd to anomalies of delay-of-reinforcement gradients. with a normal gradient, responses followed after a long delay by a reinforcer may share in the effects of that reinforcer; with a diminished or steepened gradient they may fail to do so. steepened gradients differentially select rapidly emitted responses (hyperactivity), and they limit the effectiveness with which extended stimuli become conditioned reinforcers, so that observing behavior is less well maintained (attention deficit). impulsiveness also follows from steepened gradients, which increase the effectiveness of smaller, more immediate consequences relative to larger, more delayed ones. individuals who vary in the degree to which their delay gradients are steepened will show different balances between hyperactivity and attention deficit. given the range of adhd phenomena addressed, it may be unnecessary to appeal to additional behavioral processes such as extinction deficit. extinction deficit is more likely a derivative of attention deficit, in that failure to attend to stimuli differentially correlated with extinction should slow its progress. the account suggests how relatively small differences in delay gradients early in development might engender behavioral interactions leading to very large differences later on. the steepened gradients presumably originate in properties of neurotransmitter function, but behavioral interventions that use consistently short delays of reinforcement to build higher-order behavioral units as a scaffolding to support complex cognitive and social skills may nonetheless be feasible.

The author of this fascinating book explores the problem of decision-making. As a basis, he uses hyperbolic discounting theory to discuss many basic assumptions related to self-control. In an accessible conversational tone, he succeeds in capturing many current problems in decision science and presents a rational framework for further work.

Before a general cognitive model for recurrent complex visual hallucinations (RCVH) is accepted, there must be more research into the neuropsychological and cognitive characteristics of the various disorders in which they occur. Currently available data are insufficient to distinguish whether the similar phenomenology of RCVH across different disorders is in fact produced by a single or by multiple cognitive mechanisms.

Unless restricted to explicitly held, sharable beliefs that control and justify a person's behavior, the notion of a rule has little value as an explanatory concept. Similarity-based processing is a general characteristic of the mind-world interface where internal processes (including explicitly represented rules) act on the external world. The distinction between rules and similarity is therefore misconceived.

Arbib's gestural-origins theory does not tell us why or how a subsequent switch to vocal language occurred, and shows no systematic concern with the signalling affordances or constraints of either medium. Our frame/content theory, in contrast, offers both a vocal origin in the invention of kinship terms in a baby-talk context and an explanation for the structure of the currently favored medium.

similar to directional asymmetries in animals, language lateralization in humans follows a bimodal distribution. a majority of individuals are lateralized to the left and a minority of individuals are lateralized to the right side of the brain. however, a biological advantage for either lateralization is lacking. the scenario outlined by vallortigara & rogers (v&r) suggests that language lateralization in humans is not specific to language or human speciation but simply follows an evolutionarily conserved organizational principle of the brain.

can we understand brain lateralization in humans by analysis in terms of an evolutionarily stable strategy? the attempt to demonstrate a link between lateralization in humans and that in, for example, fish appears to hinge critically on whether the isomorphism is viewed as a matter of homology or homoplasy. consideration of human handedness presents a number of challenges to the proposed framework.

Waking hallucinations suggest mechanisms of dream initiation and maintenance. Visual association cortex activation, yielding poorly attended-to, visually ambiguous dream environments, suggests conditions favoring hallucinosis. Attentional and visual systems, coactivated during sleep, may generate imagery that is inserted into virtual environments. Internally consistent dreaming may evolve from successive, contextually evoked images. Fluctuating arousal and context-evoked imagery may help explain dream features.

Although Arbib's extension of the mirror-system hypothesis neatly sidesteps one problem with the “gesture-first” theory of language origins, it overlooks the importance of gestures that occur in current-day human linguistic performance, and this lands it with another problem. We argue that, instead of gesture-first, a system of combined vocalization and gestures would have been a more natural evolutionary unit.

the reinforcement/extinction disorder hypothesis (sagvolden et al.) is an important counterweight to the executive dysfunction model of attention-deficit/hyperactivity disorder (adhd). however, like that model, it conceptualises adhd as pathophysiologically homogeneous, resulting from a common core dysfunction. recent studies reporting neuropsychological heterogeneity suggest that this common core dysfunction may be the scientific equivalent of a red herring.

We agree with Ainslie's general approach to intertemporal choices and self-control. However, we argue that a concept of “will” is superfluous in explaining tradeoffs between SS (smaller and sooner) and LL (larger and later) rewards in a framework of temporal goal setting and goal aggregation. We provide an alternative framework of reference point-dependent tradeoffs between SS and LL options.

The proposal regarding rules and similarity is considered in terms of ability to provide insights regarding previous work on reasoning and categorization. For reasoning, the issue is the relation between this proposal and one-process as well as two-process accounts of deduction and induction. For categorization, the issue is how the proposal would simultaneously explain both similarity-to-rule and rule-to-similarity shifts.

We argue that the Rules-Similarity continuum is only a useful formalism for particular, isolated tasks and must rest on the assumption that representations formed during a particular task are independent of other tasks. We show this to be an unrealistic conjecture. We additionally point out that describing categorization as selective weighing and abstracting of features misses the important step of discovering what the possible features are.

Collerton et al. propose that one and the same mechanism (PAD) underlies recurrent complex visual hallucinations (RCVH) in various disorders, including schizophrenia, dementia, and eye disease. The present commentary offers an alternative account of RCVH and other recurrent complex hallucinations specific to schizophrenia and related disorders only. The proposed account is consistent with the bias of schizophrenic RCVH contents toward animate, socially active entities.

we describe a possible link between coordinated lateralised group behaviour serving species survival in lower vertebrates and a striking lateralisation phenomenon found in human social behaviour: the universal preference for cradling a young infant on the left side. our exploration offers a different perspective on the role of cerebral asymmetry for the survival of both the individual and the species.

depue & morrone-strupinsky's (d&m-s's) language suggests that, unlike kent berridge, they may allow that the activity of a largely subcortical system, which is presumably often introspectively and cognitively inaccessible, constitutes affectively felt experience even when so. such experience would then be phenomenally conscious without being reflexively conscious or cognitively access-conscious, to use distinctions formulated by the philosopher ned block.