Pothos & Busemeyer (P&B) argue that quantum probability (QP) provides a descriptive model of behavior and can also provide a rational analysis of a task. We discuss QP models using Marr's levels of analysis, arguing that they make most sense as algorithmic level theories. We also highlight the importance of having clear interpretations for basic mechanisms such as interference.

Schilbach et al. contribute to neuroscience methodology through drawing on insights from the second-person approach. We suggest that they could further contribute to social neuroscience by more fully spelling out the ways in which a second-person approach to the nature and origin of thinking could transform neuroscience.

We focus on two issues: (1) an unusual, counterintuitive prediction that quantum probability (QP) theory appears to make regarding multiple sequential judgments, and (2) the extent to which QP is an appropriate and comprehensive benchmark for assessing judgment. These issues highlight how QP theory can fall prey to the same problems of arbitrariness that Pothos & Busemeyer (P&B) discuss as plaguing other models.

If cognitive effort indexes opportunity costs, it should be investigated like other cost factors including risk and delay. We discuss recent methodological advances in behavioral economics and neuroeconomics, highlighting our own work in measuring the subjective (economic) value of cognitive effort. We discuss the implications of Kurzban et al.'s proposal and how some of its predictions may be untestable without behavioral economic formalisms.

Our discussion of the commentaries begins, at the evolutionary level, with issues raised by our account of the evolution of morality in terms of partner-choice mutualism. We then turn to the cognitive level and the characterization and workings of fairness. In a final section, we discuss the degree to which our fairness-based approach to morality extends to norms that are commonly considered moral even though they are distinct from fairness.

The presumption that navigation requires a cognitive map leads to its conception as an abstract computational problem. Instead of loading the question in favor of an inquiry into the metric structure and evolutionary origin of cognitive maps, the task should first be to establish that a map-like representation actually is operative in real animals navigating real environments.

Based on mirror neurons' properties, viewers are emotionally engaged when observing others – even when not actively interacting; therefore, characterizing non-participatory action-viewing as isolated may be misleading. Instead, we propose a continuum of socio-emotional engagement. We also highlight recent developmental work that uses a second-person perspective, investigating behavioral, physiological, and neural activity during caregiver–infant interactions.

We address points of confusion pertaining to interrelations among and roles of core constructs involved in the production of performance outcomes. We do so informed by the body of work derived from Brehm's seminal motivation intensity theory – in particular an elaboration from the theory concerned with fatigue influence on effort and associated cardiovascular responses in people confronted with performance challenges.

We have argued that the neurocognitive representation of large-scale, navigable three-dimensional space is anisotropic, having different properties in vertical versus horizontal dimensions. Three broad categories organize the experimental and theoretical issues raised by the commentators: (1) frames of reference, (2) comparative cognition, and (3) the role of experience. These categories contain the core of a research program to show how three-dimensional space is represented and used by humans and other animals.

Quantum theory is a powerful framework for probabilistic modeling of cognition. Strong empirical evidence suggests the context- and order-dependent representation of human judgment and decision-making processes, which falls beyond the scope of classical Bayesian probability theories. However, considering behavior as the output of underlying neurobiological processes, a fundamental question remains unanswered: Is cognition a probabilistic process at all?

Despite the simplicity of Kurzban et al.'s framework, we argue that important information is lost in their simplification. We discuss research on delay of gratification and self-regulation that identifies key situational and psychological factors affecting how people represent rewards and costs. These factors affect the expected utilities of behavioral options and thus dramatically influence whether individuals persist on a difficult task.

In accord with social neuroscience's progression to include interactive experimental paradigms, parents' brains have been activated by emotionally charged infant stimuli – especially of their own infant – including baby cry and picture. More recent research includes the use of brief video clips and opportunities for maternal response. Among brain systems important to parenting are those involved in empathy. This research may inform recent studies of decreased societal empathy, offer mechanisms and solutions.

This comment suggests that Pothos & Busmeyer (P&B) do not provide an intuitive rational foundation for quantum probability (QP) theory to parallel standard logic and classical probability (CP) theory. In particular, the intuitive foundation for standard logic, which underpins CP, is the elimination of contradictions – that is, believing p and not-p is bad. Quantum logic, which underpins QP, explicitly denies non-contradiction, which seems deeply counterintuitive for the macroscopic world about which people must reason. I propose a possible resolution in situation theory.

Quantum probability (QP) provides a new perspective for cognitive science. However, one must be clear about the outcome the QP model is predicting. We discuss this concern in reference to modeling the subjective probabilities given by people as opposed to modeling the choice proportions of people. These two models would appear to have different cognitive assumptions.

The commentaries on our target article are surprisingly sympathetic to our overall approach to explaining subjective effort, though disagreement with particulars inevitably emerged. Here, in our response, we first review the few disagreements concerning the basic structure of our proposal, highlighting areas in which little or no resistance was voiced. Opposition to the assumptions that underlie our opportunity cost model is noticeably limited. Areas of genuine disagreement, however, include: (1) the inputs to and outputs of the relevant decision-making systems; (2) how to interpret data regarding individual differences in performance; (3) how to explain persistence on tasks that give rise to the sensation of subjective effort; and (4) the details of the relevant neuropsychological systems. Throughout we point to empirical issues raised by the commentaries and suggest research that will be useful in arbitrating points of disagreement.

Language is a social act. We have previously argued that language remains embedded in sociality because the motivation to communicate exists only within a social context. Schilbach et al. underscore the importance of studying linguistic behavior from within the motivated, socially interactive frame in which it is learnt and used, as well as provide testable hypotheses for a participatory, second-person neuroscience approach to language learning.