Future work is needed to establish that pure short-term memory is a coherent individual difference attribute that is separable from traditional compound short-term memory measures. Psychometric support for latent pure short-term memory capacity will provide an important starting point for future fine-grained analyses of the intrinsic factors that influence individual differences in math skills.

Evidence from egocentric space is cited to support bicoding of navigation in three-dimensional space. Horizontal distances and space are processed differently from the vertical. Indeed, effector systems are compatible in horizontal space, but potentially incompatible (or chaotic) during transitions to vertical motion. Navigation involves changes in coordinates, and animal models of navigation indicate that time has an important role.

As an account of the cognitive processes that support psychological essentialism, the inherence heuristic clarifies the basis of individual differences in essentialist thinking, and how they are associated with prejudice. It also illuminates the contextual variability of social essentialism, and where its conceptual boundaries should be drawn.

The use of lexical concepts in Levelt et al.'s model requires further refinement with regard to syntactic factors in lexical choice, the prevention of pleonasm, and the representation of near-synonyms within and across languages.

Based on the motor theory of language, which asserts an evolution from gestures along several stages to today's speech and language, we suggest that speech ontogeny may partly reflect speech phylogeny, in that perception of prosodic contours is an intermediary stage between a manual communication system and a fully developed language faculty.

Information processing theories of memory and skills can be reformulated in terms of how categories are physically and temporally related, a process called conceptual coordination. Dreaming can then be understood as a story-understanding process in which two mechanisms found in everyday comprehension are missing: conceiving sequences (chunking categories in time as a higher-order categorization) and coordinating across modalities (e.g., relating the sound of a word and the image of its meaning). On this basis, we can readily identify isomorphisms between dream phenomenology and neurophysiology, and explain the function of dreaming as facilitating future coordination of sequential, cross-modal categorization (i.e., REM sleep lowers activation thresholds, “unlearning”).

[Hobson et al.; Nielsen; Solms; Revonsuo; Vertes & Eastman]

There is considerable scope for developing a more explicit role for ethnography within the research program proposed in the article. Ethnographic studies of cultural micro-evolution would complement experimental approaches by providing insights into the “natural” settings in which cultural behaviours occur. Ethnography can also contribute to the study of cultural macro-evolution by shedding light on the conditions that generate and maintain cultural lineages.

We argue that the authors’ call to integrate Bayesian models more strongly with algorithmic- and implementational-level models must go hand in hand with a call for a fully developed account of algorithmic rationality. Without such an account, the integration of levels would come at the expense of the explanatory benefit that rational models provide.

We describe a neural monitor of environmental and physiological resources that informs effort expenditure. Depending on resources and environmental stability, serotonergic and dopaminergic neuromodulations favor different behavioral controls that are organized in corticostriatal loops. This broader perspective produces some suggestions and questions that may not be covered by the foraging approach to vigor of Shadmehr and Ahmed (2020).

Andrews et al. criticize Gould and colleagues for (1) failing to provide evidentiary criteria for accepting exaptationist alternatives to adaptationist explanations, and (2) seeing exaptations and spandrels as being far more frequent than adaptations in the evolutionary history of modern humans. I argue that the first of these criticisms is wrong, and the second reflects a bias for the classical version of Darwinian evolutionary theory, which Gould was trying to expand by proposing concepts like exaptation and spandrels.

Extending the findings of this work: Tribal peoples need study. Monogamy as marital institution and monogamy as sociosexual orientation must be separated. Sociosexuality must be considered as an aspect of somatic as well as reproductive effort; third-party interventions in sociosexuality need attention; and multiple sociosexual orientations, with frequency-dependent fitness payoffs equal at equilibrium, need to be modeled.

Nell restricts cruelty to hominids, although good evidence suggests that secondary aggression in rodents and particularly primates may be considered cruel. A considerable literature shows that glucocorticoid secretion stimulated by stress facilitates learning, memory, arousal, and aggressive behavior. Either secondary aggression (to a conspecific) or increased affiliative behavior reduces stressor-induced activity, suggesting the reward system can be satisfied by other behaviors than cruelty.

There is both empirical evidence that supports, and does not support, the four basic tastes, as well as the labeled-line and across-fiber pattern theories. All of these concepts have proven useful to researchers investigating taste coding, and should be appreciated for their heuristic value. Dismissal of any of them is neither supported by evidence nor productive.

Some things in our environment are not what they seem, and they provide a challenge to theories of concepts that emphasize similarity. Section 1 of my commentary explores a dilemma this situation creates for Machery. Section 2 describes a more general problem for prototype and exemplar theories. Section 3 locates a place for similarity-based concepts, and indicates an alternative to Machery's thesis.

The topics discussed in this response are in four broad areas: (1) Idea generation, including the failure to discuss and teach idea generation and how to nurture new ideas (sect. R2), sources of ideas worth testing with self-experimentation (sect. R3), and unusual features of the situation that may have increased the discovery rate (sect. R4); (2) Miscellaneous methodological issues, such as the value of mental experiments (sect. R5) and the limitations of double-blind experiments (sect. R6); (3) Subject-matter issues, including the relationship of this work to other evolutionary psychology studies and a new way to test evolutionary explanations (sect. R7), as well as questions about the mood results (sect. R8) and the weight results (sect. R9); and (4) Self-experimentation, including its difficulty (sect. R10) and future (sect. R11).

I respond to the many thoughtful suggestions and concerns of my commentators on a wide variety of questions. These include whether moral norms form a unified category, whether they have a distinctive phenomenology, and/or whether moral normativity is a cultural construct; whether moral externalization is necessary for correlated interaction or human prosociality; precisely how such externalization generates correlated interactions among prosocial agents; and whether there are any convincing alternative explanations for it.

We applaud Campbell's cogent arguments for the evolution of female survival mechanisms but take issue with several key conceptual claims: the treatment of patriarchy; the implicit assumption that women are passive pawns in a male game of media exploitation; and the neglect of the possibility that media images exploit existing evolved psychological mechanisms rather than create them.

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.