This commentary presents indirect support for Corballis's claim that language evolved out of a gestural system in our evolutionary past. Specifically, it presents behavioral and neurological evidence that present-day speech and gesture continue to be tightly integrated in language production and comprehension.

There is remarkable agreement between Ruchkin et al.'s psychophysiological views and my own model, based on developmental-experimental evidence, of working memory as activated long-term memory (LTM). I construe subvocal rehearsal as an operative scheme that maintains order information and demands attentional resources. Encoding and retrieving operations also demand attention. Another share of resources is used for keeping activated specific LTM representations.

Phillips & Silverstein argue that schizophrenia is a result of a deficit of the contextual coordination of neuronal responses. The authors propose that NMDA-receptors control these modulatory effects. However, hallucinations, which are among the principle symptoms of schizophrenia, imply a flaw in the interactions between neurons that is more fundamental than just a general weakness of contextual modulation.

The current model, based on event-related potential (ERP) studies, posits that the working-memory system is a state of activated long-term memory; this appears comprehensive, but it needs further detailed analysis of functional neural connectivity analysis within the prefrontal cortex (PFC) and between the posterior and prefrontal cortex. Specifically, the role of dorsolateral PFC and anterior cingulate cortex (ACC) is probably critical for PFC's attentional controller. Neural implementation of the executive function in working memory appears critical to build a firm model.

Human right-handedness does not originate in vocalisation as such but in selection pressures for structuring complex sequences of digital signals internally, as if in a vacuum. Cautious receivers cannot automatically accept signals in this way. Biological displays are subjected to contextual scrutiny on a signal-by-signal basis – a task requiring coordination of both hemispheres. In order to explain left cerebral dominance in human manual and vocal signalling, we must therefore ask why it became adaptive for receivers to abandon caution, processing zero-cost signals rapidly and on trust.

In this commentary on Stanovich & West (S&W) we call attention to two points: (1) Freud's original dual process theory, which antedates others by some seventy-five years, deserves inclusion in any consideration of dual process theories. His concepts of primary and secondary processes (Systems 1 and 2, respectively) anticipate significant aspects of current dual process theories and provide an explanation for many of their characteristics. (2) System 1 is neither rational nor irrational, but instead a-rational. Nevertheless, both the a-rational System 1 and the rational System 2 can each have different roles in enhancing evolutionary fitness. Lastly, System 1 operations are incorrectly deemed “rational” whenever they increase evolutionary fitness.

Numerous searches have failed to identify a single co-occurrence of total blindness and schizophrenia. Evidence that blindness causes loss of certain NMDA-receptor functions is balanced by reports of compensatory gains. Connections between visual and anterior cingulate NMDA-receptor systems may help to explain how blindness could protect against schizophrenia.

In this commentary, we focus on four points. First, we discuss the assertion that the unitary model explains dissociations that implicate multiple systems. Second, the distinct nature of information utilized in immediate- and delayed-recall supports the distinct memory systems view. Third, the variable nature of capacity limits corroborates this view. Finally, we review event-related fMRI results that suggest support for multiple systems.

Stanovich & West (S&W), following all relevant others, define the rationality debate in terms of human performance on certain well-known problems. Unfortunately, these problems are very easy. For that reason, if System 2 cognition is identified with the capacity to solve them, such cognition will not enable humans to meet the cognitive demands of our technological society. Other profound issues arise as well.

Corballis suggests that apes lack voluntary control over their vocal production. However, recent evidence implicates voluntary control of vocalizations in apes, which suggests that intentional control of vocal communication predates the hominid-pongid split. Furthermore, the ease with which apes in captivity manipulate the visual attention of observers implies a common cognitive basis for joint attention in humans and apes.

Individual differences are indeed an important aid to our understanding of human cognition, but the importance of the rationality debate is open to question. An understanding of the process involved, and how and why differences occur, is fundamental to our understanding of human reasoning and decision making.

Impairments in cognitive coordination in schizophrenia are supported by phenomenological data that suggest deficits in the processing of visual context. Although the target article is sympathetic to such a phenomenological perspective, we argue that the relevance of phenomenological data for a wider understanding of consciousness in schizophrenia is not sufficiently addressed by the authors.

Although visual long-term memory (VLTM) and visual short-term memory (VSTM) can be distinguished from each other (and from visual sensory storage [SS]), they are embodied within the same modality-specific brain regions, but in very different ways: VLTM as patterns of connectivity and VSTM as patterns of activity. Perception and VSTM do not “activate” VLTM. They use VLTM to create novel patterns of activity relevant to novel circumstances.

Corballis argues that language underwent two modality switches – from vocal to manual, then back to vocal. Speech has evolved a frame/content mode of organization whereby consonants and vowels (content) are placed into a syllable structure of frames (MacNeilage 1998). No homologue to this mode is present in sign language, raising doubt as to whether the proposed modality switches could have occurred.

We argue that an approach that treats short-term memory as activated long-term memory is not inherently in conflict with information recycling in a limited-capacity or working-memory store, or with long-term storage based on the processing in such a store. Language differences aside, real model differences can only be assessed when the contrasting models are formulated precisely.

In chronic schizophrenic patients with both positive and negative symptoms (see Table 1), interhemispheric connections at the high frequency beta2-rhythm are absent during cognitive tasks, in contrast to normal controls, who have many interhemispheric connections at this frequency in the same situation. Connectivity is a fundamental brain feature, evidently greatly promoted by the NMDA system. It is a more reliable measure of brain function than the spectral power of this rhythm.

We did not, as Brakel & Shevrin imply, intend to classify either System 1 or System 2 as rational or irrational. Instrumental rationality is assessed at the organismic level, not at the subpersonal level. Thus, neither System 1 nor System 2 are themselves inherently rational or irrational. Also, that genetic fitness and instrumental rationality are not to be equated was a major theme in our target article. We disagree with Bringsjord & Yang's point that the tasks used in the heuristics and biases literature are easy. Bringsjord & Yang too readily conflate the ability to utilize a principle of rational choice with the disposition to do so. Thus, they undervalue tasks in the cognitive science literature that compellingly reveal difficulties with the latter. We agree with Newton & Roberts that models at the algorithmic level of analysis are crucial, but we disagree with their implication that attention to issues of rationality at the intentional level of analysis impedes work at the algorithmic level of analysis.

Ontogenetic factors constrain the evolution of species-typical traits. Because human infants are born “prematurely” relative to other primates, the development of handedness during infancy can reveal important ontogenetic influences on handedness that may have contributed to the evolution of the human species-typical trait of a population-level right-hand dominance.

The identity of working-memory and long-term memory representations follows from many lines of evidence. However, the data provided by Ruchkin et al. are hardly compelling, as they make unproved assumptions about hypothetical generators. We cite studies from our lab in which congruent slow-wave topographies were found for short-term and long-term memory tasks, strongly suggesting that both activate identical cell assemblies.

Corballis suggests that fully vocal communication was invented by modern humans between 170,000 and 50,000 years ago. Because this new form of communication did not require hand gestures, he wondered whether this may have facilitated the development of lithic manufacture. I cast doubt on this interesting notion but offer an enhanced version that may have more potential.