Kurzban et al. make a convincing case against the idea that willpower is a depleting resource. However, they do not advance a positive account of willpower. Rather than treating “willpower” as a synonym of “executive function,” we argue that the term willpower should be designated for mechanisms individuals deploy to reduce dynamic inconsistency in their behavior.

Although mutually advantageous cooperative strategies might be an apt account of some societies, other moral systems might be needed among certain groups and contexts. In particular, in a duty-based moral system, people do not behave morally with an expectation for proportional reward, but rather, as a fulfillment of debt owed to others. In such systems, mutualistic motivations are not necessarily a key component of morality.

There are several facets of second-person neuroscience which can benefit from comparisons with animal behavioral neuroscience studies. This commentary addresses the challenges involved in obtaining quantitative data from second-person techniques, the role of stress in inducing robust responses, the use of interactive functional magnetic resonance imaging (fMRI), and the value of applying interactive methods to studies of aggression and depression.

We show that, given extensive exploration of a three-dimensional volume, grid units can form with the approximate periodicity of a face-centered cubic crystal, as the spontaneous product of a self-organizing process at the single unit level, driven solely by firing rate adaptation.

Though the aversiveness of effort may indeed serve in selecting tasks for executive attention, the notion that it reflects opportunity costs is questionable: The potency of distractions in real-life situations is not regularly related with the potential benefit from attending to them.

Use of quantum probability as a top-down model of cognition will be enhanced by consideration of the underlying complex-valued wave function, which allows a better account of interference effects and of the structure of learned and ad hoc question operators. Furthermore, the treatment of incompatible questions can be made more quantitative by analyzing them as non-commutative operators.

The dimension of spatial representations can be assessed by above-chance performance in novel shortcut or spatial reasoning tasks independent of accuracy levels, systematic biases, mosaic/segmentation across space, separate coding of individual dimensions, and reference frames. Based on this criterion, humans and some other animals exhibited sufficient evidence for the existence of three-dimensional and/or four-dimensional spatial representations.

The target article convincingly argues that mutualistic cooperation is supported by partner choice. However, we will suggest that mutualistic cooperation is not the basis of fairness; instead, fairness is based on impartiality. In support of this view, we show that adults are willing to destroy others' resources to avoid inequality, a result predicted by impartiality but not by mutualistic cooperation.

Kurzban et al.'s opportunity cost model of mental effort relies heavily on counterfactual thinking. We suggest that a closer inspection of the role of counterfactual emotions, and particularly of action/inaction asymmetries in anticipated regret, may be important in understanding the role of opportunity costs in decisions to persist with a current task.

A lot of research in cognition and decision making suffers from a lack of formalism. The quantum probability program could help to improve this situation, but we wonder whether it would provide even more added value if its presumed focus on outcome models were complemented by process models that are, ideally, informed by ecological analyses and integrated into cognitive architectures.

We resist Schilbach et al.'s characterization of the “social perception” approach to social cognition as a “spectator theory” of other minds. We show how the social perception view acknowledges the crucial role interaction plays in enabling social understanding. We also highlight a dilemma Schilbach et al. face in attempting to distinguish their second-person approach from the social perception view.

Pothos & Busemeyer (P&B) argue convincingly that quantum probability offers an improvement over classical Bayesian probability in modeling the empirical data of cognitive science. However, a weakness related to restrictions on the dimensionality of incompatible physical observables flows from the authors' “agnosticism” regarding quantum processes in neural substrates underlying cognition. Addressing this problem will require either future research findings validating quantum neurophysics or theoretical expansion of the uncertainty principle as a new, neurocognitively contextualized, “local” symmetry.

Kurzban et al. associate mental effort and fatigue with a hypothetical mechanism able to estimate the utilities of possible actions and then select the action with a maximal utility. However, this approach faces fundamental problems. In my opinion, mental effort and fatigue are results of a conflict between the monotony of long-term activities and the novelty-processing systems.

The vertical component of space occurs in two distinct fashions in natural environments. One kind of verticality is orthogonal-to-horizontal (as in climbing trees, operating in volumetric spaces such as water or air, or taking elevators in multilevel buildings). Another kind of verticality, which might be functionally distinct, comes from navigating on sloped terrain (as in traversing hills or ramps).

Both evolutionary and developmental research indicate that humans are adapted to respecting property rights, independently (and possibly orthogonally) of considerations of fairness. We offer evidence from psychological experiments suggesting that enforcing one's rights and respecting others' possessions are basic cognitive mechanisms automatically activated and grounded in humans' sensory-motor system. This may entail an independent motivation that is more profound than considerations of fairness and impartiality.

Although a second-person neuroscience has high ecological validity, the extent to which a second- versus third-person neuroscience approach fundamentally alters neural patterns of activation requires more careful investigation. Nonetheless, we are hopeful that this new avenue will prove fruitful in significantly advancing our understanding of typical and atypical social cognition.

Kurzban et al.'s expectancy-value mechanism of effort allocation seems relevant in situations when familiar tasks are initiated. However, we think additional mechanisms are important when people continue with a task for a prolonged time. These mechanisms, which are particularly relevant for performance of novel or urgent tasks, involve neural systems that track performance costs and resources.

We propose to understand social affordances in the broader context of responsiveness to a field of relevant affordances in general. This perspective clarifies our everyday ability to unreflectively switch between social and other affordances. Moreover, based on our experience with Deep Brain Stimulation for treating obsessive-compulsive disorder (OCD) patients, we suggest that psychiatric disorders may affect skilled intentionality, including responsiveness to social affordances.

Baumard et al. provide an intriguing model where morality emerges from the dynamics of partner choice in mutualistic interactions. I discuss evidence from human and nonhuman primates that supports the overall approach, but highlights a gap in explaining the human specificity of moral cognition. I suggest that an essential characteristic of human fairness is to override concerns about merit in favor of promoting the welfare in others who are needy.

The suggestion that three-dimensional space is represented by a mosaic of neural map fragments, each covering a small area of space in the plane of locomotion, receives support from studies in complex two-dimensional environments. How map fragments are linked, which brain circuits are involved, and whether metric is preserved across fragments are questions that remain to be determined.