The target article adopts an adaptationist research strategy that, while logically coherent, suffers from various limitations, including problems in reconstructing past selective environments, ambiguity in how narrowly to define adaptive problems or selection pressures, and an overemphasis on specialization in evolved psychological mechanisms. To remedy these problems, I support a more flexible approach involving phenotypic adaptation and cultural evolution.

Thomas & Karmiloff-Smith (T&K-S) provide evidence from computational modeling against modular assumptions of “Residual Normality” (RN) in developmental disorders. Even though I agree with their criticism, I find their choice of empirical evidence disappointing. Cognitive neuroscience cannot as yet provide a complete understanding of most developmental disorders, but what is known is more than enough to debunk the idea of RN.

The concept of “intrinsic reinforcement” stretches the use of “reinforcement” beyond where it is valuable. The concept of the “self-system,” though fuzzy at the edges, can cover experience as well as the behaviour of altruistic acts.

Wynn's thesis that the acquisition of the rules of symmetry comprised the formative factor in the evolution of human spatial cognition is questioned on several grounds, including the ubiquity of symmetry across species and the apparent hard-wired nature of its evolution in both humans and animals.

Rachlin's thought-provoking analysis could be strengthened by greater openness to evolutionary interpretation and the use of the directed attention concept as a component of self-control. His contribution to the understanding of prosocial behavior would also benefit from abandoning the traditional (and excessively restrictive) definition of altruism.

The developmental modeling approach to investigating developmental disorders appears highly promising. In this commentary, we question the untapped potential of this approach for supporting insights into particular developmental disorders, developmental processes across the life span, and the viability of traditional theories of developmental disorders.

Currently there is considerable interest in the notion that dorsal and ventral visual systems might differ in their specializations for thought and action. Behavior invariably involves multiple processes such as perception, judgment, and response execution. It is not clear that characteristics of the dorsal and ventral processing streams, as described by Norman, are entirely of a perceptual nature.

Rather than starting with traits and speculating whether selective forces drove evolution in past environments, we propose starting with a candidate gene associated with a trait and testing first for patterns of selection at the DNA level. This can provide limitations on the number of traits to be evaluated subsequently by adaptationism as described by Andrews et al.

Rachlin basically marshals three reasons behind his unconventional claim that altruism is a subcategory of self-control and that, hence, the prisoner's dilemma is the appropriate metaphor of altruism. I do not find any of the three reasons convincing. Therefore, the prisoner's dilemma metaphor is unsuitable for explaining altruism.

One of the debated issues regarding Residual Normality (RN) is frequency sensitivity in Williams syndrome (WS). We present some data on frequency sensitivity in Hungarian WS subjects. Based on vocabulary measures, we suggest that instead of the across-the-board frequency insensitivity proposed by some, a higher frequency threshold characterizes these subjects’performance. Results from a category fluency task show that whereas frequency sensitivity in WS is in line with controls, error patterns imply a qualitatively distinct, looser categorical organization. Regarding the much-debated issue of morphological overgeneralizations, our data suggest that frequency sensitivity cuts across the divisions proposed by dual-process theories. In general, some of the frequency effects are the same as in typically developing populations, but with a delayed pattern. Frequency may be interpreted as supporting RN, but in WS it operates with higher thresholds that might be a general processing feature of WS individuals.

I claim that the increase in complexity in the (known) trace of Paleolithic stone tools can be parsimoniously explained by postulating the emergence of effective mechanisms for the social transmission of representations. I propose that Paleolithic tools, similar to more contemporary tools, were subject to a process of evolution by artificial selection based on functionality.

Norman's aim to reconcile two longstanding and seemingly opposed philosophies of perception, the constructivist and the ecological, by casting them as approaches to complementary subsystems within the visual brain is laudable. Unfortunately, Norman overreaches in attempting to equate direct perception with dorsal/unconscious visual processing and indirect perception with ventral/conscious visual processing. Even a cursory review suggests that the functional and neural segregation of direct and indirect perception is not as clear as the target article would suggest.

The expression exapted as is offered as a substitute for the target article's exaptation for and exaptation to on the grounds that exapted as is less likely to foster the pernicious intuition that natural selection designs for future consequences.

Perception, as Gibson described it – picking up information that specifies the real local situation – includes not only perceiving affordances and controlling small movements, but also seeing the large-scale environmental layout and the position/movement of the “ecological self.” If the dorsal cortical system is also responsible for that very significant achievement, its activity must be at least partly conscious.

Biological, cognitive, and learning explanations of altruism, selfishness, and self-control can be integrated in terms of adaptive strategies. The key to understanding why humans and other animals sometimes resist temptation and sacrifice their immediate interests for the sake of others lies in mapping the design of the evolved mental mechanisms that give rise to the decisions in question.

Thomas & Karmiloff-Smith (T&K-S) claim that “Residual Normality” is a priori unlikely, that is, that specific cognitive deficits should not exist in developmental disorders. Here I review evidence that a specific cognitive deficit is at the core of developmental dyslexia and I provide a possible neurological account thereof.

Evolutionary theories of human cognition should refer to specific times in the primate or hominid past. Though alternative accounts of tool manufacture from Wynn's are possible (e.g., frontal lobe function), Wynn demonstrates the power of archaeology to guide cognitive theories. Many cognitive abilities evolved not in the “Pleistocene hunter-gatherer” context, but earlier, in the context of other patterns of social organization and foraging.

Andrews et al.'s analysis suffers from a series of conceptual confusions they inherit from Gould's work. Their proposal that adaptations can be distinguished from exaptations essentially by specific design criteria fails because exaptations are often maintained and secondarily adapted by natural selection and therefore, over evolutionary time, can come to have similar levels of design specificity to adaptations.

Thomas & Karmiloff-Smith (T&K-S) raise an issue of considerable theoretical importance: Are developmental disorders like cases of adult brain damage? However, a related question: Are developmental disabilities the same in children and adults? is rarely addressed. Failure to consider the cumulative and differing effects of aberrant development across the life span confounds the current literature on both developmental dyslexia and Specific Language Impairment.

Comparisons are drawn between two theories of visual perception and two modes of information processing. Characteristics delineating dorsal and ventral visual systems lack internal consistency, probably because they are not completely separable. Mechanism is inherent when distinguishing these systems, and becomes more apparent with different processing domains. What is lacking is a more explicit means of linking these theories.