Attention-deficit/hyperactivity disorder (ADHD) is currently defined as a cognitive/behavioral developmental disorder where all clinical criteria are behavioral. Inattentiveness, overactivity, and impulsiveness are presently regarded as the main clinical symptoms. The dynamic developmental behavioral theory is based on the hypothesis that altered dopaminergic function plays a pivotal role by failing to modulate nondopaminergic (primarily glutamate and GABA) signal transmission appropriately. A hypofunctioning mesolimbic dopamine branch produces altered reinforcement of behavior and deficient extinction of previously reinforced behavior. This gives rise to delay aversion, development of hyperactivity in novel situations, impulsiveness, deficient sustained attention, increased behavioral variability, and failure to “inhibit” responses (“disinhibition”).

A hypofunctioning mesocortical dopamine branch will cause attention response deficiencies (deficient orienting responses, impaired saccadic eye movements, and poorer attention responses toward a target) and poor behavioral planning (poor executive functions). A hypofunctioning nigrostriatal dopamine branch will cause impaired modulation of motor functions and deficient nondeclarative habit learning and memory. These impairments will give rise to apparent developmental delay, clumsiness, neurological “soft signs,” and a “failure to inhibit” responses when quick reactions are required.

A hypofunctioning mesocortical dopamine branch will cause attention response deficiencies (deficient orienting responses, impaired saccadic eye movements, and poorer attention responses toward a target) and poor behavioral planning (poor executive functions). A hypofunctioning nigrostriatal dopamine branch will cause impaired modulation of motor functions and deficient nondeclarative habit learning and memory. These impairments will give rise to apparent developmental delay, clumsiness, neurological “soft signs,” and a “failure to inhibit” responses when quick reactions are required.

There is a continuum between prototypical cases of rule use and prototypical cases of similarity use. A prototypical rule: (1) is explicitly represented, (2) can be verbalized, and (3) requires that the user selectively attend to a few features of the object, while ignoring the others. Prototypical similarity-use requires that: (1) the user should match the object to a mental representation holistically, and (2) there should be no selective attention or inhibition. Neural evidence supports prototypical rule-use. Most models of categorization fall between the two prototypes.

Perhaps the greatest evolutionary advantage conferred by spoken language was its ability to communicate mentalistic concepts, rather than just extending the vocabulary of action already served by an imitation function. An appreciation that the mirror-neuron system served a simple mentalising function before gestural communication sets Arbib's theory in a more appropriate social cognitive context.

it is argued in the target article that hemispheric lateralization is advantageous when faced with conflicting choices. as decision-making processes must have been subject to a strong selection pressure, the sensitivity of response latencies could suggest a modular and hierarchical organization of behavioral execution, as was formulated by tinbergen (1951).

Numerous questions remain unanswered concerning the functional determinants of symbolic behavior and perspective-taking, particularly regarding the capabilities of children with autism. An alternative approach that considers these behaviors to be forms of derived relational responding allows for the design of functional intervention programs to establish such repertoires in individuals for whom they are absent.

It is difficult to see how one can support the continuum between rules and similarity, as Pothos proposes. A similarity theory could dispense with the rules end of the continuum. The only thing that we need is one (or more than one) theory of similarity that goes beyond the stimulus-carrying information and behavioristic restrictions that have usually been attributed to similarity theories.

Henrich et al. describe an innovative research program investigating cross-cultural differences in the selfishness axiom (in economic games) in humans, yet humans are not the only species to show such variation. Chimpanzees and capuchin monkeys show signs of deviating from the standard self-interest paradigm in experimental settings by refusing to take foods that are less valuable than those earned by conspecifics, indicating that they, too, may pay attention to relative gains. However, it is less clear whether these species also show the other-regarding preferences seen in humans.

Our tolerance for, and promotion of, linguistic irregularity is a key arbitrator between Arbib's proposal that holistic protolanguage preceded culturally imposed compositionality, and the standard view that discrete units with word-like properties came first. The former, coupled with needs-only analysis, neatly accounts for the second-order linguistic complexity that is rationalised as fuzzy grammaticality, subclass exception, and full irregularity.

whether or not trait affiliation correlates with human behaviour needs investigating. one should be careful generalizing neuropsychological mechanisms for affiliation, and generalizing an analysis based on one or two neuropsychological mechanisms and mostly studies on rodents, to complex human social interactions. serotonin is an example of a neurotransmitter playing an important role in cooperation and interacting with the dopaminergic system.

Although provocative, the data reported in Henrich et al.'s target article suffer from limitations, including the fact that the “selfishness axiom” is not an interesting null hypothesis, and the intrinsic limitations of quasi-experimental designs, in which random assignment is impossible. True experiments, in the laboratory or in the field, will continue to be crucial for settling core issues associated with human economic behavior.

sunstein aims to provide a nonsectarian account of moral heuristics, yet the account rests on a controversial meta-ethical view. further, moral theorists who reject act consequentialism may deny that sunstein's examples involve moral mistakes. but so what? within a theory that counts consequences as a morally weighty feature of actions, the moral judgments that sunstein points to are indeed mistaken, and the fact that governmental action at odds with these judgments will be controversial doesn't bar such action.

The Simplicity and Power (SP) theory (Wolff 2003a) provides support for Pothos's proposals by illustrating how the effect of “rules” and “similarity” may be achieved within an integrated model that makes no explicit provision for either concept. The theory is described here in outline with simple examples to show how rules and similarity can emerge as properties of the system in learning, reasoning, categorization, and the parsing of language.

the construct for affiliation in depue & morrone-strupinsky's (d&m-s's) study is restricted to the interpersonal domain. this restriction is not found in other disciplines. it may be necessary in early stages of trait research. but the construct will need to be expanded to speak to the more complex, second-order affiliations of which humans are capable.

In the dyadic and triadic sharing of emotions, intentions, and behaviors in families, interactive synchrony is important to the early life experiences that contribute to the development of cultural cognition. This synchrony likely depends on neurobiological circuits, currently under study with brain imaging, that involve attention, stress response, and memory.

Early and automatic neuropsychological processes may be influenced by altered dopaminergic functions but cannot be fully explained by these or by altered reinforcement and extinction processes. The reinforcement- extinction model is excellent for understanding certain causal pathways of attention-deficit/hyperactivity disorder (ADHD), but it can hardly explain the heterogeneous developmental trajectories of ADHD fully. It should be integrated into a multiple pathways model.

Our computational studies of infant language learning estimate the inherent difficulty of Arbib's proposal. We show that body language provides a strikingly helpful scaffold for learning language that may be necessary but not sufficient, given the absence of sophisticated language in other species. The extraordinary language abilities of Homo sapiens must have evolved from other pressures, such as sexual selection.

if, as is not implausible, the correct moral theory is indexed to human capacity for moral reasoning, then the thesis that moral heuristics exist faces a serious objection. this objection can be answered by embracing a wide reflective equilibrium account of the origins of our normative principles of morality.

We have shown in a computational model that a poor memory for context could result in some of the behaviors associated with ADHD, which is well in line with the dynamic developmental theory. Given the important role of context in extinction, a weaker context due to a steeper delay-of-reinforcement gradient would result in impaired inhibition.

Challenges for extending the mirror system hypothesis include mechanisms supporting planning, conversation, motivation, theory of mind, and prosody. Modeling remains relevant. Co-speech gestures show how manual gesture and speech intertwine, but more attention is needed to the auditory system and phonology. The holophrastic view of protolanguage is debated, along with semantics and the cultural basis of grammars. Anatomically separated regions may share an evolutionary history.

This response to the open peer commentary discusses what should be the appropriate explanatory scope of a rules versus similarity proposal and accordingly evaluates the Rules versus Similarity one. Additionally, coherence, goals, and commitment are presented as inferential notions, fully consistent with the Rules versus Similarity distinction, that allow us to predict when Rules would be preferred to Similarity.