Effects of Tool Novelty and Action Demands on Gaze Searching During Tool Observation

On the functional brain networks involved in tool-related action understanding

Tool-use skills represent a significant cognitive leap in human evolution, playing a crucial role in the emergence of complex technologies. Yet, the neural mechanisms underlying such capabilities are still debated. Here we explore with fMRI the functional brain networks involved in tool-related action understanding. Participants viewed images depicting action-consistent (e.g., nail-hammer) and action-inconsistent (e.g., scarf-hammer) object-tool pairs, under three conditions: semantic (recognizing the tools previously seen in the pairs), mechanical (assessing the usability of the pairs), and control (looking at the pairs without explicit tasks). During the observation of the pairs, task-based left-brain functional connectivity differed within conditions. Compared to the control, both the semantic and mechanical conditions exhibited co-activations in dorsal (precuneus) and ventro-dorsal (inferior frontal gyrus) regions. However, the semantic condition recruited medial and posterior temporal areas, whereas the mechanical condition engaged inferior parietal and posterior temporal regions. Also, when distinguishing action-consistent from action-inconsistent pairs, an extensive frontotemporal neural circuit was activated. These findings support recent accounts that view tool-related action understanding as the combined product of semantic and mechanical knowledge. Furthermore, they emphasize how the left inferior parietal and anterior temporal lobes might be considered as hubs for the cross-modal integration of physical and conceptual knowledge, respectively.

Cognitive Archeology and the Attentional System: An Evolutionary Mismatch for the Genus Homo

Brain evolution is a key topic in evolutionary anthropology. Unfortunately, in this sense the fossil record can usually support limited anatomical and behavioral inferences. Nonetheless, information from fossil species is, in any case, particularly valuable, because it represents the only direct proof of cerebral and behavioral changes throughout the human phylogeny. Recently, archeology and psychology have been integrated in the field of cognitive archeology, which aims to interpret current cognitive models according to the evidence we have on extinct human species. In this article, such evidence is reviewed in order to consider whether and to what extent the archeological record can supply information regarding changes of the attentional system in different taxa of the human genus. In particular, behavioral correlates associated with the fronto-parietal system and working memory are employed to consider recent changes in our species, Homo sapiens, and a mismatch between attentional and visuospatial ability is hypothesized. These two functional systems support present-moment awareness and mind-wandering, respectively, and their evolutionary unbalance can explain a structural sensitivity to psychological distress in our species.

Cultural evolution in the science of culture and cultural evolution

My critical review [1] elicited a welcome diversity of perspectives across the 12 commentaries now published [2-13]. In total 28 co-authors were inspired to contribute. In addition to engaging with the critical perspectives of my review, several of the commentaries take the debates and discussions into insightful and potentially important supplementary domains that I highlight in what follows. I have extracted a number of major themes in which I detected overlaps in the foci of different commentaries, and I use these to organise my replies. I hope that our shared efforts will constitute some degree of 'cultural evolution' in our science, as suggested in the title of this reply to commentaries.

The visual encoding of graspable unfamiliar objects

We explored by eye-tracking the visual encoding modalities of participants (N = 20) involved in a free-observation task in which three repetitions of ten unfamiliar graspable objects were administered. Then, we analysed the temporal allocation (t = 1500 ms) of visual-spatial attention to objects' manipulation (i.e., the part aimed at grasping the object) and functional (i.e., the part aimed at recognizing the function and identity of the object) areas. Within the first 750 ms, participants tended to shift their gaze on the functional areas while decreasing their attention on the manipulation areas. Then, participants reversed this trend, decreasing their visual-spatial attention to the functional areas while fixing the manipulation areas relatively more. Crucially, the global amount of visual-spatial attention for objects' functional areas significantly decreased as an effect of stimuli repetition while remaining stable for the manipulation areas, thus indicating stimulus familiarity effects. These findings support the action reappraisal theoretical approach, which considers object/tool processing as abilities emerging from semantic, technical/mechanical, and sensorimotor knowledge integration.

Semantic congruency effects of prime words on tool visual exploration

Most recent research on human tool use highlighted how people might integrate multiple sources of information through different neurocognitive systems to exploit the environment for action. This mechanism of integration is known as "action reappraisal". In the present eye-tracking study, we further tested the action reappraisal idea by devising a word-priming paradigm to investigate how semantically congruent (e.g., "nail") vs. semantically incongruent words (e.g., "jacket") that preceded the vision of tools (e.g., a hammer) may affect participants' visual exploration of them. We found an implicit modulation of participants' temporal allocation of visuospatial attention as a function of the object-word consistency. Indeed, participants tended to increase over time their fixations on tools' manipulation areas under semantically congruent conditions. Conversely, participants tended to concentrate their visual-spatial attention on tools' functional areas when inconsistent object-word pairs were presented. These results support and extend the information-integrated perspective of the action reappraisal approach. Also, these findings provide further evidence about how higher-level semantic information may influence tools' visual exploration.