In the target article, Schilbach et al. defend a “second-person neuroscience” perspective that focuses on the neural basis of social cognition during live, ongoing interactions between individuals. We argue that a second-person neuroscience would benefit from formal approaches borrowed from economics and behavioral ecology and that it should be extended to social interactions in nonhuman animals.

The target article highlights the role of the anterior cingulate cortex (ACC) in conflict monitoring, but ACC function may be better understood in terms of the hierarchical organization of behavior. This proposal suggests that the ACC selects extended goal-directed actions according to their learned costs and benefits and executes those behaviors subject to depleting resources.

Jeffery et al. suggest that three-dimensional environments are not represented according to their volumetric properties, but in a quasi-planar fashion. Here we take into consideration the role of visual experience and the use of technology for spatial learning to better understand the nature of the preference of horizontal over vertical spatial representation.

Mutualistic theory explains convincingly the prevalence of fairness norms in small societies of foragers and in large contemporary democratic societies. However, it cannot explain the U-shaped curve of egalitarianism in human history. A theory based on bargaining power is able to provide a more general account and to explain mutualism as a special case. According to this approach, social norms may be more variable and malleable than Baumard et al. suggest.

The “Orch OR” theory suggests that quantum computations in brain neuronal dendritic-somatic microtubules regulate axonal firings to control conscious behavior. Within microtubule subunit proteins, collective dipoles in arrays of contiguous amino acid electron clouds enable “quantum channels” suitable for topological dipole “qubits” able to physically represent cognitive values, for example, those portrayed by Pothos & Busemeyer (P&B) as projections in abstract Hilbert space.

Advancing second-person neuroscience will need strong theories, as well as the new methods detailed by Schilbach et al. I assess computational theories, enactive theories, and cognitive/information processing theories, and argue that information processing approaches have an important role to play in second-person neuroscience. They provide the closest link to brain imaging and can give important insights into social behaviour.

We explain here how the natural selection theory of people's mutualistic sense of fairness and the biofunctional theory of human understanding are made for each other. We welcome the stage that the target article has already set for this convergence, and invite the authors to consider moving the two independently developed approaches a step closer to the natural selection level of biofunctional understanding.

The opportunity cost model (OCM) aims to explain various phenomena, among which the finding that performance degrades if executive functions are used repeatedly (“resource depletion”). We argue that an OCM account of resource depletion requires two unlikely assumptions, and we discuss an alternative that does not require these assumptions. This alternative model describes the interplay between executive function and motivation.

I consider the general problem of category conjunctions in the light of Pothos & Busemeyer (P&B)'s quantum probability (QP) account of the conjunction fallacy. I argue that their account as presented cannot capture the “guppy effect” – the case in which a class is a better member of a conjunction A^B than it is of either A or B alone.

A second-person neuroscience, as an emerging area of neuroscience and the behavioral sciences, cannot afford to avoid a bottom-up, subcortical, and conative-affective perspective. An example with canid social play and a modern motivational behavioral neursocience will illustrate our point.

We describe an augmented topological map as an alternative for the proposed bicoded map. Inverting causality, the special nature of the vertical dimension is then no longer fixed a priori and the cause of specific navigation behavior, but a consequence of the combination of the specific geometry of the experimental environment and the motor capabilities of the experimental animals.

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.

Second-person neuroscience offers a framework for the study of social emotions, such as embarrassment and pride. However, we propose that an enduring mental representation of oneself in relation to others without a continuous direct social interaction is possible. We call this state “social immersion” and will explain its impact on the neuroscience of social emotions.

Baumard et al. attribute to humans a sense of fairness. However, the properties of this sense are so underspecified that the evolutionary account offered is not well-motivated. We contrast this with the framework of Universal Moral Grammar, which has sought a descriptively adequate account of the structure of the moral domain as a precondition for understanding the evolution of morality.

The opportunity cost model offers an ultimate explanation of ego depletion that helps to move the field beyond biologically improbable resource accounts. The model's more proximate explanation, however, falls short of accounting for much data and is based on an outdated view of human rationality. We suggest that our own process model offers a better proximate account of self-control fatigue.

We concentrate on two aspects of the article by Pothos & Busemeyer (P&B): the relationship between classical and quantum probability and quantum probability as a basis for rational decisions. We argue that the mathematical relationship between classical and quantum probability is not quite what the authors claim. Furthermore, it might be premature to regard quantum probability as the best practical rational scheme for decision making.

We highlight methodological and theoretical limitations of the authors' Dirac formalism and suggest the von Neumann open systems approach as a resolution. The open systems framework is a generalization of classical probability and we hope it will allow cognitive scientists to extend quantum probability from perception, categorization, memory, decision making, and similarity judgments to phenomena in learning and development.

We argue that prioritization, simultaneity, and mutual exclusion are mind-body integration functions that can't be addressed meaningfully at the psychological (computational) level alone. We describe the outlook for an integration between Kurzban et al.'s profound discussion of opportunity cost/benefit prioritization and decades of related development in biofunctional science.

Baumard and colleagues put forward a new hypothesis about the nature and evolution of fairness. In this commentary, we discuss the relation between morality and their views about fairness.

Schilbach et al.'s model assumes that the ability to “experience” minds is already present in human infants and therefore falls foul of the very intellectualist problems it attempts to avoid. We propose an alternative relational, action-based account, which attempts to grasp how the individual's construction of knowledge develops within interactions.