Mirror neurons may play a role in representing not only signs but also their meaning. Because actions are the only aspect of behavior that are inter-individually accessible, interpreting meanings in terms of actions might explain how meanings can be shared. Behavioral evidence and artificial life simulations suggest that seeing objects or processing words referring to objects automatically activates motor actions.

Criteria that aim to dichotomize cognition into rules and similarity are destined to fail because rules and similarity are not in genuine conflict. It is possible for a given cognitive domain to exploit rules without similarity, similarity without rules, or both (rules and similarity) at the same time.

Arbib presents a reasoned explanation for language evolution from nonhuman to human primates, one that I argue can be equally applied to animals trained in forms of interspecies communication. I apply his criteria for language readiness and language (in actuality, protolanguage) to the behavior of a Grey parrot (Psittacus erithacus) taught to communicate with humans using rudiments of English speech.

This commentary reviews and extends the target article's treatment of the topic of the role of acetylcholine in hallucinatory experience in health and disease. Particular attention is paid to differentiating muscarinic and nicotinic effects in modulating the use of virtual reality mechanisms by the brain. Then, attention is drawn to the similarities between these aspects of brain function and certain aspects of television digital compression technology.

the term “moral heuristic” as used by sunstein seeks to bring together various traditions. however, there are significant differences between uses of the term “heuristic” in the cognitive and the social psychological research, and these differences are accompanied by very distinct evidential criteria. we suggest the term “moral heuristic” should refer to processes, which means that further evidence is required.

We propose that the crucial difference between human cognition and that of other species is the ability to participate with others in collaborative activities with shared goals and intentions: shared intentionality. Participation in such activities requires not only especially powerful forms of intention reading and cultural learning, but also a unique motivation to share psychological states with others and unique forms of cognitive representation for doing so. The result of participating in these activities is species-unique forms of cultural cognition and evolution, enabling everything from the creation and use of linguistic symbols to the construction of social norms and individual beliefs to the establishment of social institutions. In support of this proposal we argue and present evidence that great apes (and some children with autism) understand the basics of intentional action, but they still do not participate in activities involving joint intentions and attention (shared intentionality). Human children's skills of shared intentionality develop gradually during the first 14 months of life as two ontogenetic pathways intertwine: (1) the general ape line of understanding others as animate, goal-directed, and intentional agents; and (2) a species-unique motivation to share emotions, experience, and activities with other persons. The developmental outcome is children's ability to construct dialogic cognitive representations, which enable them to participate in earnest in the collectivity that is human cognition.

Tomasello et al. give a good account of how shared intentionality develops in children, but a much weaker one of how it might have evolved. They are unduly hasty in dismissing the emergence of language as a triggering factor. An alternative account is suggested in which language provided the spark, but thereafter language and shared intentionality coevolved.

We tested Collerton et al.'s model of visual hallucinations by re-examining a data set for correlations between visual hallucinations and measures of attentional function in schizophrenia patients. These data did not support their model. We suggest that cortical hyperexcitability plays an important role in hallucinations, and propose an alternative model that links evidence for cortical hyperexcitability with abnormal neural dynamics.

the authors regard opiates as the primary neural substrate for social attachment, and peptide hormones as subsidiary. one may instead conclude from their evidence that oxytocin, vasopressin, and opiates play complementary roles in attachment. oxytocin and vasopressin relate to different aspects of emotional experience, and opiates to quiescence from long-term attachment. this is related to intimacy versus affiliation.

The possible role of the neurotransmitter serotonin in human affiliative behavior is under-examined in the review by Depue & Morrone- Strupinsky (D&M-S). This commentary reviews evidence indicating that serotonin not only inhibits aggressive behavior that may be detrimental to affiliative bonds with others in a social group but serotonin also enhances prosocial behaviors that may facilitate ties to the social group.

Infectious yawning and laughing offer a convenient, noninvasive approach to the evolution, development, production, and control of imitation-like and mirror-like phenomena in normal, behaving humans.

Pothos suggests dispensing with the distinction between rules and similarity, without defining what is meant by either term. We agree that there are problems with the distinction between rules and similarity, but believe these will be solved only by exploring the representations and processes underlying cases purported to involve rules and similarity.

interesting as the experiments are, their relevance to the real-life situation is rendered questionable by the unthinking use of given singularities as target objects. the evolutionary process does not respect what one agent takes to be a singular referent. a “singling” from the continuum is rather a varying feature of the necessity to track what is rewarding in it.

Ignoring most published evidence on wild chimpanzees, Tomasello et al.'s claim that shared goals and intentions are uniquely human amounts to a faith statement. A brief survey of chimpanzee hunting tactics shows that group hunts are compatible with a shared goals and intentions hypothesis. The disdain of observational data in experimental psychology leads some to ignore the reality of animal cognitive achievements.

Arbib derives the origin of language from the emergence of a complex imitation system; however, it is unlikely that this complication could occur without a prior complicating within the imitated systems. This means that Arbib's hypothesis is not correct, because the other systems determined the appearance of language. In my opinion, language emerged when the motivational system became able to support goal-directed processes with no innate basis.

Contrary to Pothos, rule- and similarity-based processes cannot be distinguished by dimensionality. Rather, one must consider the goal of the processing: what the system will do with the resulting representations. Research on speech perception demonstrates that the degree to which speech categories are gradient (or similarity-based) is a function of the utility of within-category variation for further processing.

The etiology of visual hallucinations is largely undetermined in schizophrenia. Collerton et al.'s PAD model partly concurs with what we know about neurocognition in schizophrenia, but we need to specify the types of perceptual and attentional abnormalities that are implicated in recurrent complex visual hallucinations (RCVH). Available data suggest that abnormal attentional control and top-down processing play a larger role than the ventral stream deficits.

depue & morrone-strupinsky (d&m-s) present a thorough case for the role of “reward” brain circuits in affiliative bonding. integration of information in the nucleus accumbens shell (na), the role of dopamine in this processing, and opioid (primarily via mu receptors) control of these circuits are the primary elements of the model. although the overall picture is quite compelling, the description leans excessively in the view of dopamine systems as “reward” circuits.

Drawing on an example from artificial grammar learning, I present the case that similarity processes can be computationally identical to rules processes, but that participants in an artificial grammar learning experiment may use different processing modes to classify stimuli. The number of properties and other representational differences between rule and similarity processes are an accidental consequence of strategies used.

Commentators agree that the Perception and Attention Deficit (PAD) model is a promising model for accounting for recurrent complex visual hallucinations (RCVH) across several disorders, though with varying detailed criticisms. Its central tenets are not modified, but further consideration of generative models of visual processing and the relationship of proto-objects and memory systems allows the PAD model to deal with variations in phenomenology. The commentaries suggest new ways to generate evidence that will test the model.