The hypothesis that dreaming is involved in off-line memory processing is difficult to test because major methodological issues have to be addressed, such as dream recall and the effect of remembered dreams on memory. It would be fruitful – in addition to studying the ancient art of memory (AAOM) in a scanner – to study the dreams of persons who use AAOM regularly.

Cross-cultural personality research suggests that individuals from wealthier countries tend to be more open-minded. This openness to values may support more democratic governments and the expansion of fundamental freedoms. The link between wealth and freedom is evident in cold-to-temperate climates, but not across wealthy nations in hot climates. Furthermore, temperature and economic conditions shape perceptions of national character stereotypes.

McCullough et al. present a compelling case that anger-based revenge is designed to disincentivize the target from imposing costs on the vengeful individual. Here I present a contrast between revenge motivated by anger (as discussed in the target article) and revenge motivated by hatred, which remains largely unexplored in the literature.

A psycho-historical framework for the science of art appreciation will be an experimental discipline that may shed new light on the highest capacities of the human brain, yielding new scientific ways to talk about the art appreciation. The recent findings of the contextual information processing in the human brain make the concept of the art-historical context clear for empirical experimentation.

Social signaling models predict that subtle variation in climatic temperature induces systematic changes in expressed cognition. An experiment showed that perceived room temperature was associated with variability in self-descriptions, social reactions of others, and desiring differing types of social networks. The findings reflect the tendency to inflate capacity demonstrations in warmer climates as a result of the social networking opportunities they enable.

Links with the Humanities are to be welcomed, but they cannot be exempted from normal scientific criteria. Any hypothesis regarding the function of dreams that is premised on rapid eye movement (REM)/dream isomorphism is unsupportable on empirical grounds. Llewellyn's hypothesis has the further problem of counter-evidence in respect of its claim that dreaming relies upon hippocampal functions. The hypothesis also lacks face validity.

The important roles of prediction and prior experience are well established in music research and fit well with Clark's concept of unified perception, cognition, and action arising from hierarchical, bidirectional predictive processing. However, in order to fully account for human musical intelligence, Clark needs to further consider the powerful and variable role of affect in relation to prediction error.

Art appreciation often involves contemplation beyond immediate perceptual experience. However, there are challenges to incorporating such processes into a comprehensive theory of art appreciation. Can appreciation be captured in the responses to individual artworks? Can all forms of contemplation be defined? What properties of artworks trigger contemplation? We argue that such questions are fundamental to a psycho-historical framework for the science of art appreciation, and we suggest research that may assist in refining this framework.

Insofar as South Africa underwent a rapid transformation from apartheid to democracy, it may provide a unique laboratory for investigating aspects of revenge and forgiveness. Here we suggest that observations and data from South Africa are partially consistent with the hypotheses generated by MCullough and colleagues. At the same time, the rich range of revenge and forgiveness phenomena in real-life settings is likely to require explanatory concepts other than specialized modules and their computational outputs.

The neurocognitive evidence that Pickering & Garrod (P&G) cite in favor of positing forward models in speech production is not compelling. The data to which they appeal either cannot be explained by forward models, or can be explained by a more parsimonious model.

Pickering & Garrod (P&G) consider the possibility that inner speech might be a product of forward production models. Here I consider the idea of inner speech as a forward model in light of empirical work from the past few decades, concluding that, while forward models could contribute to it, inner speech nonetheless requires activity from the implementers.

The Bayesian brain hypothesis provides an attractive unifying framework for perception, cognition, and action. We argue that the framework can also usefully integrate interoception, the sense of the internal physiological condition of the body. Our model of “interoceptive predictive coding” entails a new view of emotion as interoceptive inference and may account for a range of psychiatric disorders of selfhood.

Neuroimaging studies show that episodic memory encoding is associated with increased activity in hippocampus and lateral prefrontal cortex; however, the latter structure shows decreased activity in rapid eye movement (REM) sleep. Together with few episodic memory traces in REM sleep, and REM sleep deprivation affecting hippocampus-independent emotional processes, this argues for generic information processing in REM sleep rather than linking episodic memory traces.

Forty-nine commentators have reviewed the theory that needs-based stresses and freedoms are shaped differently in threatening, comforting, and challenging climato-economic habitats. Their commentaries cover the white domain, where the theory does apply (e.g., happiness, collectivism, and democracy), the gray domain, where it may or may not apply (e.g., personality traits and creativity), and the black domain, where it does not apply (e.g., human intelligence and gendered culture). This response article provides clarifications, recommendations, and expectations.

I question both the necessity and the sufficiency of Bullot & Reber's (B&R's) aesthetic modes. I argue that they have not shown how the aesthetic modes are truly “aesthetic” – how they concern our experience of artworks as opposed to other kinds of experiences or why the modes are individually necessary for one. I suggest the causal dependence of the modes should be modified.

McCullough et al.'s functionalist model of revenge is highly compatible with the person-centered approach to moral judgment, which emphasizes the adaptive manner in which social perceivers derive character information from moral acts. Evidence includes act–person dissociations in which an act is seen as less immoral than a comparison act, yet as a clearer indicator of poor moral character.

The study of spatial cognition has provided considerable insight into how animals (including humans) navigate on the horizontal plane. However, the real world is three-dimensional, having a complex topography including both horizontal and vertical features, which presents additional challenges for representation and navigation. The present article reviews the emerging behavioral and neurobiological literature on spatial cognition in non-horizontal environments. We suggest that three-dimensional spaces are represented in a quasi-planar fashion, with space in the plane of locomotion being computed separately and represented differently from space in the orthogonal axis – a representational structure we have termed “bicoded.” We argue that the mammalian spatial representation in surface-travelling animals comprises a mosaic of these locally planar fragments, rather than a fully integrated volumetric map. More generally, this may be true even for species that can move freely in all three dimensions, such as birds and fish. We outline the evidence supporting this view, together with the adaptive advantages of such a scheme.

Although predictive coding may offer a computational principle that unifies perception and action, states with different directions of fit are involved (with indicative and imperative contents, respectively). Predictive states are adjusted to fit the world in the course of perception, but in the case of action, the corresponding states act as a fixed target towards which the agent adjusts the world. This well-recognised distinction helps side-step some problems discussed in the target article.

Llewellyn has written a fascinating article about rapid eye movement (REM) dreams and how they promote the elaborative encoding of recent memories. The main message of her article is that hyperassociative and fluid cognitive processes during REM dreaming facilitate consolidation. We consider one potential implication of this analysis: the possibility that excessive or out-of-phase REM sleep fuels dissociative symptomatology. Further research is warranted to explore the psychopathological ramifications of Llewellyn's theory.

I evaluate the bottlenecks involved in the simulation mechanism underpinning superior predictive abilities for upcoming actions. This perceptual-motor state is characterized by a complex interrelationship designed to make predictions using a highly fine-tuned and constrained motor operation. The extension of such mechanisms to language may occur only in sensorimotor circuits devoted to the action domain.