Robert Koch (1843–1910) discovered the causal agents for tuberculosis, cholera, and anthrax. The 1905 Nobel Prize acknowledged Koch's criteria for identifying the causal agent of an infectious disease. These criteria remain useful and the data reviewed below show that the cholinergic contributions to REM sleep control are confirmed by Koch's postulates.

[Hobson et al.]

Cesario misrepresents experimental social psychology. The discipline encompasses significantly more than implicit bias research, including controlled decision making and real-world behavioral observations. Paradoxically, while critiquing popular implicit bias tasks, Cesario also describes task refinements that have significantly advanced their external validity and our contextual understanding of bias. Thus rather than abandonment, a call for “continued improvement” is a far more sensible proposition.

Erdelyi's “unified theory of repression” attempts to rehabilitate psychoanalytic doctrine by exaggerating its compatibility with the findings of cognitive science. In addition, Erdelyi treats Freud's writings as holy writ, any portion of which can be quoted to prove a point. He also relies on a long-discredited account of Freud's “seduction theory” and ignores important links between Freudian assumptions and our recent recovered memory movement.

As reported by Vertes & Eastman, convincing evidence rules out any role for REM sleep in memory consolidation. However, they do not provide convincing evidence for their claim that sleep in generaI – as opposed to REM sleep per se – has no influence on memory consolidation. Recent correlational data suggest that the number of NREM/REM cycles is associated with performance on a verbal recall task.

[Vertes & Eastman]

We believe the dichotomy of processes introduced in the target article is highly speculative, because the dichotomy is shaped by the questionable assumption of modularity and the complementary assumption of locality. As a result, the author falls into a line of circular reasoning that biases his analysis of the experimental and neuropsychological data, and weakens the proposed model.

Psychologists have long debated the underlying cause of infants' perseverative reaching. Thelen et al. explain the error in terms of general processes that make goal-directed actions to remembered locations. The context- and experience-dependent nature of their model implies that there is no single cause of the A-not-B error, and, more generally, no core essence to cognitive development.

The search for general processes that underlie intelligence in nonhumans has followed two strategies: one that concerns observing differences between nonhuman species (G), the second that concerns observing individual differences within a nonhuman species (g). This commentary takes issue with both attempts to mark a general factor: Differential responding to contextual variables compromises the search for G, and the lack of predictive validity compromises g.

Deictic pointers allow the nervous system to exploit information in a frame that is centered on the object of interest. This processing may take place in visual or haptic space, but the information processing advantages of deictic pointing can also be applied in abstract spaces, providing the basis for analogical transfer. Simulation and behavioral results illustrating this progression from embodiment to abstraction are discussed.

Uchiyama et al. describe how a more complete measurement of the dynamic nature of culture could help us unmask the true richness of genetic effects on behaviour. I underscore this notion here by reflecting on the role that the dynamic relationship between culture and DNA has played in our evolutionary history and will play in our evolutionary future.

Evidence from aphasia is considered that leads to a distinction between abstract and concrete thought processes and hence for a distinction between rules and similarity. It is argued that perceptual classification is inherently a rule-following procedure and these rules are unable to be followed when a patient has difficulty with name comprehension and retrieval.

This commentary deals with the relation between human language and nonverbal signals used by nonhuman primates. It suggests that human language could have developed through the interaction of procedural learning with a preexisting system for socio-affective communication. The introduction of “content” into existing “frames” requires a neurobiologically plausible learning mechanism.

Additional experiments show that P-consciousness and A consciousness can be empirically dissociated for the theoretically so phisticated observer. Phenomenal consciousness can have several degrees that are indirectly measurable.

A single evolved psychological mechanism, social identity, may help explain the development of salient sex differences in aggression. Bearing children automatically provides a basis for positive social identity for females. Masculine identity is more problematic, especially where the range of possible cultural roles is small. Ethnohistorical data provides insight into the overlap between masculine values and warrior values.