Llewellyn's claim that rapid eye movement (REM) dream imagery may be related to the processes involved in memory consolidation during sleep is plausible. However, whereas there is voluntary and deliberate intention behind the construction of images in the ancient art of memory (AAOM) method, there is a lack of intentionality in producing dream images. The memory for dreams is also fragile, and dependent on encoding once awake.

The artistic design stance is an important part of art appreciation, but it remains unclear how it can be applied to artworks for which art historical context is no longer available, such as Ice Age art. We propose that some of the designer's intentions can be gathered noninferentially through direct experience with prehistoric artworks.

The target article's important point is easily misunderstood to claim that all revenge is adaptive. Revenge and forgiveness can overstretch (or understretch) the bounds of utility due to misperceptions, minimization of costly errors, a breakdown within our evolved revenge systems, or natural genetic and developmental variation. Together, these factors can compound to produce highly abnormal instances of revenge and forgiveness.

A cornerstone of the target article is that, in a predictive coding framework, attention can be modelled by weighting prediction error with a measure of precision. We argue that this is not a complete explanation, especially in the light of ERP (event-related potentials) data showing large evoked responses for frequently presented target stimuli, which thus are predicted.

Both children and adults predict the content of upcoming language, suggesting that prediction is useful for learning as well as processing. We present an alternative model which can explain prediction behaviour as a by-product of language learning. We suggest that a consideration of language acquisition places important constraints on Pickering & Garrod's (P&G's) theory.

There are interesting parallelisms between McCullough et al.'s article and studies of revenge presented by French legal anthropologist Raymond Verdier, particularly as regards the discussion of the increasing likelihood of revenge with increasing social distance. Additionally, the observation that many peoples speak of revenge in the language of debt and repayment, links it with exchanges of benefits as well as costs.

Does the interaction between climactic demands, monetary resources, and freedom suggest a more general relationship between the environmental challenges that human societies face and their resources to meet those challenges? Using data on press freedom (Van de Vliert 2011a), we found no evidence of a similar interaction with natural resources (as measured by oil exports) or risk for natural disasters.

The sensory cortex has been interpreted as coding information rather than stimulus properties since Sokolov in 1960 showed increased response to an unexpected stimulus decrement. The motor cortex is also organized around expectation, coding the goal of an act rather than a set of muscle movements. Expectation drives not only immediate responses but also the very structure of the cortex, as demonstrated by development of receptive fields that mirror the structure of the visual world.

Accepting Bullot & Reber's (B&R's) criteria for art appreciation would confine the study of aesthetics to those works for which historical information is available, mainly post–eighteenth-century Western “high art.” We reject their contention that “correct” artistic understanding is limited to experts with detailed knowledge or education in art, which implies a narrowly elitist conception of aesthetics. Scientific aesthetics must be broadly inclusive.

We propose that rapid eye movement (REM) and slow-wave sleep contribute differently to the formation of episodic memories. REM sleep is important for building up invariant object representations that eventually recur to gamma-band oscillations in the neocortex. In contrast, slow-wave sleep is more directly involved in the consolidation of episodic memories through replay of sequential neural activity in hippocampal place cells.

Van de Vliert's findings fit nicely with our recent arguments implying that (1) differentiated selfhood is partly motivated by requirements of cultural groups, and (2) free will mainly exists within culture. Some cultural groups promote individual freedom, whereas others constrict it so as to maintain elites' power and privilege. Thus, freedom is, to a great extent, a creation of culture.

We encourage Pickering & Garrod (P&G) to implement this promising theory in a computational model. The proposed theory crucially relies on having an efficient and reliable mechanism for early intention recognition. Furthermore, the generation of impoverished predictions is incompatible with a number of key phenomena that motivated P&G's theory. Explaining these phenomena requires fully specified perceptual predictions in both comprehension and production.

The question that we deal with in this commentary is the need to clarify the synergistic role of different non–rapid eye movement (NREM) sleep stages (stages 2 and 3–4) with REM and while awake in elaborative encoding of episodic memory. If the assumption is that there is isomorphism between neuronal and cognitive networks, then more detailed analysis of NREM sleep and dreams is absolutely necessary.

Clark examines the notion of the “predictive brain” as a unifying model for cognitive neuroscience, from the level of basic neural processes to sensorimotor control. Although we are in general agreement with this notion, we feel that there are many details that still need to be fleshed out from the standpoint of perception and action.

McCullough et al. argue that humans possess evolved computational systems for implementing retaliatory behavior that both deters aggression and promotes subsequent reconciliation. However, they do not apply this analysis to the sphere of intergroup relations. We believe their model can be usefully extended to this domain and discuss why this would be possible, pertinent, and productive.

Bullot & Reber (B&R) put forth a design stance to fuse psychological and art historical accounts of visual thinking into a single theory. We argue that this aspect of their proposal needs further fine-tuning. Issues of transgression and coherence are necessary to provide stability to the design stance. We advocate looking to Art Education for such fundamentals of picture understanding.

In her target article, Sue Llewellyn concludes that an unconstrained form of consciousness is necessary for the elaboration of meaningful associations. Unlike the author's view that dedifferentiation of memory encoding processes across wakefulness and sleep determines schizophrenia, our proposal suggests this mechanism could reflect a common neurobiological substrate for psychosis across several different diagnostic domains.

Van de Vliert proposes a comprehensive explanation for differences in “freedoms” in diverse human populations based on climate and monetary resources. This intriguing approach, though derived from an evolutionary view covering all species, is based exclusively on human populations. This anthropocentric lens is challenged by ways of testing Van de Vliert's thesis more generally using playfulness as a surrogate for freedom.

Clark's essay lays the foundation for a Bayesian account of the “projection” of consciously perceived properties: The expectations that our brains test against inputs concern the particular affordances that evolution has designed us to care about, including especially expectations of our own expectations.

General systems for reciprocity explain the same phenomena as the target article's proposed revenge system, and can explain other cooperative phenomena. We need more reason to hypothesise a specific revenge system. In addition, the proposed calculus of revenge is less sensitive to absolute magnitudes of revenge than it should be.