Many motivational constructs are opaque “black boxes,” and should be replaced by an explicit account of the underlying psychological mechanisms. The theory of motivational systems has begun to provide such an account. I recently contributed to this tradition with a general architecture of motivation, which connects “energization” and “direction” through the goal-setting activity of emotions, and serves as an evolutionary grounded map of motivational processes.

Murayama and Jach argue that it is not clearly specified how motivation constructs produce behavior and that this black box should be unpacked. We argue that the authors overlook important classic theory and highlight recent research programs that already started unboxing. We feel that without relying on the mechanisms that such programs uncover, the proposed computational approach will be fruitless.

Murayama and Jach offer valuable suggestions for how to integrate computational processes into motivation theory, but these processes cannot do away with motivation altogether. Rewards are only rewarding because people want and like them – that is, because of motivation. Sexual desire is not primarily a quest for rewarding information. Elucidating the interface between motivation and cognition seems a promising way forward.

Murayama and Jach point out that we do not sufficiently understand the constructs and mental computations underlying higher-order motivated behaviors. Although this may be generally true, we would like to add and contribute to the discussion by outlining how interdisciplinary research on novelty-evoked exploration has advanced the study of learning and curiosity.

In their article, Murayama and Jach contend that a mental computational model demonstrates that high-level motivations are emergent properties from underlying cognitive processes rather than instigators of behaviors. Despite points of agreement with the authors' critiques of the motivation literature, I argue that their claim of dismantling the black box of the human mind has been constructed on shaking grounds.

Endogenous reward (intrinsic reward at will) is a fiat currency that is occasioned by steps toward any goals which are challenging and/or uncommon enough to prevent its debasement by inflation. A “theory of mental computational processes” should propose what properties let goals grow from appetites for endogenous rewards. Endogenous reward may be the universal selective factor in all modifiable mental processes.

The constructs of motivation (or needs, motives, etc.) to explain higher-order behavior have burgeoned in psychology. In this article, we critically evaluate such high-level motivation constructs that many researchers define as causal determinants of behavior. We identify a fundamental issue with this predominant view of motivation, which we call the black-box problem. Specifically, high-level motivation constructs have been considered as causally instigating a wide range of higher-order behavior, but this does not explain what they actually are or how behavioral tendencies are generated. The black-box problem inevitably makes the construct ill-defined and jeopardizes its theoretical status. To address the problem, we discuss the importance of mental computational processes underlying motivated behavior. Critically, from this perspective, motivation is not a unitary construct that causes a wide range of higher-order behavior – it is an emergent property that people construe through the regularities of subjective experiences and behavior. The proposed perspective opens new avenues for future theoretical development, that is, the examination of how motivated behavior is realized through mental computational processes.

The target article explores material culture datasets from three African forager groups. After demonstrating that these modern, contemporary human populations would leave scant evidence of symbolic behaviour or material complexity, it cautioned against using material culture as a barometer for human cognition in the deep past. Twenty-one commentaries broadly support or expand these conclusions. A minority offer targeted demurrals, highlighting (1) the soundness of reasoning from absence; and questioning (2) the “cognitively modern” null; (3) the role of hunter-gatherer ethnography; and (4) the pertinence of the inferential issues identified in the target article. In synthesising these discussions, this reply addresses all four points of demurral in turn, and concludes that there is much to be gained from shifting our null assumptions and reconsidering the probabilistic inferential links between past material culture and cognition.

Our species' behavioral and cognitive evolution constitute a key research topic across many scientific disciplines. Based on ethnographic hunter-gatherer data, Stibbard-Hawkes challenges the common link made between past material culture and cognitive capacities. Despite this adequate criticism, archaeology must retain a central role for studying these issues due to its unique access to relevant empirical evidence in deep time.

Stibbard-Hawkes challenges the link between symbolic material evidence and behavioural modernity. Extending this to non-human species, we find that personal adornment, decoration, figurative art, and musical instruments may not uniquely distinguish human cognition. These common criteria may ineffectively distinguish symbolic from non-symbolic cognition or symbolic cognition is not uniquely human. It highlights the need for broader comparative perspectives.

Shared intentionality is the derived hominin motivation and skills to align mental states. Research on the role of interdependence in the phylogeny of shared intentionality has only considered the archeological record of Homo heidelbergensis. But ethnographic and fossil data must be considered, too. Doing so suggests that shared intentionality may have been favored in Homo erectus to support persistence hunting.

The absence of symbolic material cultural objects in the archaeological record does not prove absence of symbolic cognition. Sometimes perishable materials are selected for symbolic roles, for practical concerns or to indicate a temporary condition. Also some symbolic functions may predate the use of durable materials. Finally, child play and artisan experimentations usually involve cheap and perishable materials. These are symbolic and representational activities that do not leave a material trace.

Stibbard-Hawkes forcefully alerts us to the pitfall of false-negative reasoning in symbolic archaeology. We highlight the twin problem of false-positive reasoning in what we call the “false-symbol problem.” False symbols are intuitively special entities that, owing to their non-utilitarian nature, invite symbolic interpretation. But they are not symbolic. We link the false-symbol problem to work in comparative primate cognition, taking “primate art” as our main example.

Stibbard-Hawkes shows that cultures using material symbols might well not leave traces of that practice in the archaeological record. The paper thus poses an important challenge: When is absence of evidence evidence of absence? This commentary uses behavioural ecology to make modest progress on this problem.

Stibbard-Hawkes' taphonomic findings are valuable, and his call for caution warranted, but the hazards he raises are being mitigated by a multi-pronged approach; current research on behavioural/cognitive modernity is not based solely on material chronology. Theories synthesize data from archaeology, anthropology, psychology, neuroscience, and genetics, and predictions arising from these theories are tested with mathematical and agent-based models.

Using modern hunter-gatherers to infer about early Homo sapiens only works if at least (a) modern hunter-gatherers represent an unbiased sample of humanity, and (b) modern hunter-gatherers act in ways similar to the behavior of early Homo sapiens. Both of these are false, leading to the problem of whether we can draw conclusions about early Homo sapiens from modern hunter-gatherers.

I expand Stibbard-Hawkes' exploration of symbolism and cognition to suggest that we also ought to reconsider the strength of connections between cognition and technological complexity. Using early weaponry as a case study I suggest that complexity may be “hidden” in early tools, and further highlight that assessments of technologies as linear and progressive have roots in Western colonial thought.

We welcome Stibbard-Hawkes's empirical contributions and discussion of interpretive challenges for archaeology, but question some of his characterizations and conclusions. Moving beyond critique, it is time to develop new research methods that eschew simplistic modern/premodern binaries. We advocate an inductive, probabilistic approach using multiple lines of evidence to infer the causes and consequences of behavioral variability across time and space.

We comment on the consequences of the target article for language evolution research. We propose that the default assumption should be that of language-readiness in extinct hominins, and the integration of different types of available evidence from multiple disciplines should be used to assess the likely extent of the realization of this readiness. The role of archaeological evidence should be reconsidered.

The article provides an important warning but its general conclusions should be nuanced: (i) When there is no evidence for it, we should depart from the hypothesis that a species lacks a particular cognitive capacity, and (ii) inferences from absence of evidence can be epistemically sound and scientifically strategic in cognitive and linguistic archaeology.