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Abstract Background Dexterous tool use is considered to be underpinned by model-based control relying on acquired internal models of tools. In particular, this is the case in situations where available sensory feedback regarding the consequences of tool use is restricted. In the present study, we conducted an fMRI study to identify cerebellar involvement in model-based estimation of tool-use consequences using tracking tasks with different levels of visual feedback. Methods Twenty healthy right-handed adults participated in this study. These participants tracked a moving target on a screen with a cursor controlled by a joystick using their right hand during fMRI scanning. For each trial, the level of visual feedback for cursor position was randomly selected from three task conditions, namely, Precise, Obscure, and No conditions. Results A conjunction analysis across all task conditions found extensive activation of the right cerebellum, covering the anterior lobe (lobule V) and inferior posterior lobe (lobule VIII). Also, contrasts among the three task conditions revealed additional significant activation of the left superior posterior lobe (Crus I) in the No compared to the Precise condition. Furthermore, a post hoc psychophysiological interaction analysis revealed conditional modulation of functional coupling between the right, but not the left, cerebellar region and right frontoparietal regions that are involved in self-body perception. Conclusions Our data show that the left Crus I is the only region that was more active in a condition where no visual feedback for cursor position was available. This suggests that the left Crus I region plays a role in model-based estimation of tool-use consequences based on an acquired internal model of tools.

One of the most surprising features of our brain is the fact that it is extremely plastic. Among the various plastic processes supported by our brain, there is the neural representation of the space surrounding our body, the peripersonal space (PPS). The effects of real-world tool use on the PPS are well known in cognitive neuroscience, but little is still known whether similar mechanisms also govern virtual tool use. To this purpose, the present study investigated the plasticity of the PPS before and after a real (Experiment 1) or virtual motor training with a tool (Experiment 2). The results show the expansion of the PPS only following real-world tool use but not virtual use, highlighting how the two types of training potentially rely on different processes. This study enriches the current state of the art on the plasticity of PPS in real and virtual environments. We discuss our data with respect to the relevance for the development of effective immersive environment for trainings, learning and rehabilitation.

Tool use has not yet been confirmed in horses, mules or donkeys. As this subject is difficult to research with conventional methods, we used a crowdsourcing approach to gather data. We contacted equid owners and carers and asked them to report and video examples of “unusual” behaviour via a dedicated website. We also searched YouTube and Facebook for videos of equids showing tool use. From 635 reports, including 1014 behaviours, we found 20 cases of tool use, 13 of which were unambiguous in that it was clear that the behaviour was not trained, caused by reduced welfare, incidental or accidental. We then assessed (a) the effect of management conditions on tool use and (b) whether the animals used tools alone, or socially, involving other equids or humans. We found that management restrictions were associated with corresponding tool use in 12 of the 13 cases (p = 0.01), e.g., equids using sticks to scrape hay within reach when feed was restricted. Furthermore, 8 of the 13 cases involved other equids or humans, such as horses using brushes to groom others. The most frequent tool use was for foraging, with seven examples, tool use for social purposes was seen in four cases, and there was just one case of tool use for escape. There was just one case of tool use for comfort, and in this instance, there were no management restrictions. Equids therefore can develop tool use, especially when management conditions are restricted, but it is a rare occurrence.

Novel problems often partially overlap with familiar ones. Some features match the qualities of previous situations stored in long-term memory and therefore trigger their retrieval. Using relevant, while inhibiting irrelevant, memories to solve novel problems is a hallmark of behavioral flexibility in humans and has recently been demonstrated in great apes. This capacity has been proposed to promote technical innovativeness and thus warrants investigations of such a mechanism in other innovative species. Here, we show that proficient tool—users among Goffin's cockatoos—an innovative tool—using species—could use a relevant previous experience to solve a novel, partially overlapping problem, even despite a conflicting, potentially misleading, experience. This suggests that selecting relevant experiences over irrelevant experiences guides problem solving at least in some Goffin's cockatoos. Our result supports the hypothesis that flexible memory functions may promote technical innovations.

Novel problems often partially overlap with familiar ones. Some features match the qualities of previous situations stored in long-term memory and therefore trigger their retrieval. Using relevant, while inhibiting irrelevant, memories to solve novel problems is a hallmark of behavioral flexibility in humans and has recently been demonstrated in great apes. This capacity has been proposed to promote technical innovativeness and thus warrants investigations of such a mechanism in other innovative species. Here, we show that proficient tool—users among Goffin's cockatoos—an innovative tool—using species—could use a relevant previous experience to solve a novel, partially overlapping problem, even despite a conflicting, potentially misleading, experience. This suggests that selecting relevant experiences over irrelevant experiences guides problem solving at least in some Goffin's cockatoos. Our result supports the hypothesis that flexible memory functions may promote technical innovations. [ABSTRACT FROM AUTHOR]

Most neuroimaging experiments that investigate how tools and their actions are represented in the brain use visual paradigms where tools or hands are displayed as 2D images and no real movements are performed. These studies discovered selective visual responses in occipitotemporal and parietal cortices for viewing pictures of hands or tools, which are assumed to reflect action processing, but this has rarely been directly investigated. Here, we examined the responses of independently visually defined category-selective brain areas when participants grasped 3D tools (N = 20; 9 females). Using real-action fMRI and multivoxel pattern analysis, we found that grasp typicality representations (i.e., whether a tool is grasped appropriately for use) were decodable from hand-selective areas in occipitotemporal and parietal cortices, but not from tool-, object-, or body-selective areas, even if partially overlapping. Importantly, these effects were exclusive for actions with tools, but not for biomechanically matched actions with control nontools. In addition, grasp typicality decoding was significantly higher in hand than tool-selective parietal regions. Notably, grasp typicality representations were automatically evoked even when there was no requirement for tool use and participants were naive to object category (tool vs nontools). Finding a specificity for typical tool grasping in hand-selective, rather than tool-selective, regions challenges the long-standing assumption that activation for viewing tool images reflects sensorimotor processing linked to tool manipulation. Instead, our results show that typicality representations for tool grasping are automatically evoked in visual regions specialized for representing the human hand, the primary tool of the brain for interacting with the world. [ABSTRACT FROM AUTHOR]

Children recognise the social value of imitation but do not opt for tools that are 'normative' if they are also dysfunctional. We investigated whether children would replicate a normative method in a tool‐learning task if it was instrumentally functional but less efficient than an alternative. Four‐ to six‐year‐old children were presented with a sticker‐retrieving task and two equally functional tool options that differed in efficiency. The inefficient tool was highlighted as the normative option. Verbal descriptors that established the normative value of the inefficient tool (e.g., 'everybody' uses this) did not motivate children to use it. The majority of children opted for instrumental efficiency over conformity. [ABSTRACT FROM AUTHOR]

Tufted capuchin monkeys (Sapajus spp.) are the only Neotropical Primates that regularly use tools in the wild, but only one population of bearded capuchin monkeys (Sapajus libidinosus) is known to habitually use sticks as probes. In this population, males are typically the only sex to use stick tools, something unexpected, since there are no obvious physical constraints, and females do use stone tools in the wild and sticks in experimental conditions. We investigated the development of probe tool use in eight infants to clarify whether social influences on learning varied between the sexes, as tool use learning by capuchin monkeys is a socially biased process. We found that in the first 10 months of age, females manipulate sticks as much as males, but after 10–12 months of age, males begin to manipulate them at higher frequencies. We examined if social connections—as opportunities for social learning—could explain this difference and verified that, on close distance social networks, infant males and females have similar connections with older males. However, males observe probe tool use events more often than females when close to such events. The higher frequency of manipulation of sticks, as well as the higher rates of probe tool use observation, appear to be the key to understand why only males are probe tool users in this population. Since there are only male potential models of probe use, a sex motivational bias could explain the sex difference in observation; a bias in observation could explain the differences in manipulation—and manipulation rates would certainly influence the chances of individual, trial‐and‐error learning (a case of "local/stimulus enhancement"). Research Highlights: In wild capuchin monkeys, males and females have the same social opportunities to observe probe tool use.However, males observe probe tool use events more often than females when nearby a probe tool use event.Males' higher rates of probe tool use observation and higher frequencies of manipulation of sticks appear to be the key to understand why only males use probe tools. [ABSTRACT FROM AUTHOR]

Humans are distinctive in their dependence upon products of culture for survival, products that have evolved cumulatively over generations such that many cannot now be created by a single individual. Why the cultural capacity of humans appears unrivalled in the animal kingdom is a topic of ongoing debate. Here we explore whether innovation and/or social learning propensities may constrain the ability of one of our closest living relatives, chimpanzees (Pan troglodytes), to master an extractive foraging and tool-use task designed to afford opportunities for cumulative culture to develop. We further explore the potential demographic characteristics associated with novel task solutions. Chimpanzees (N = 53) were inventive, flexibly exploring the novel task, albeit complex inventions were rare and shaped by prior individual experience with similar tool-use tasks. However, they displayed no evidence of cumulative cultural learning. Communities displayed richer behavioral repertoires and had greater task success than chimpanzees tested in an asocial control condition, but their solution complexity did not surpass what individuals invented. The lack of social transmission of complex and beneficial solutions in contexts like those we studied provides one explanation for the limited cumulative culture observed in this species. [ABSTRACT FROM AUTHOR]

Tool use can be considered in terms of purposeful behaviour. This emphasis on 'purpose' hides a host of assumptions about the nature of cognition and its relationship with physical activity. In particular, a notion of 'purpose' might assume that this is teleological which, in turn, requires a model of a desired end state of an action that can be projected onto the environment. Such a model is fundamental to traditional descriptions of cognition and a version of this can be found in the 'template' theory of stone-tool production (i.e. where the maker of the tool has a model in mind and attempts to reproduce this model in stone). Against this cognitive perspective, a number of approaches have been proposed that share their roots in the work of Gibson (i.e. ecological psychology) or Bernstein (i.e. dynamic systems). From these perspectives, 'purpose' is not a matter of a projection but opportunity; put simply, an action is performed until it need not be performed further. Trivial though this might sound, it has implications for how we define purpose and how this might apply to our understanding of tool use. We argue from a dynamic systems perspective and demonstrate the use of tools to crack bones for marrow extraction. [ABSTRACT FROM AUTHOR]

Some nonhuman primates use tools to modify the behavior of other animals in social contexts. For example, during their proceptive periods, female bearded capuchins (Sapajus libidinosus) in two wild groups throw stones and push branches toward males, which may function to draw male attention to the females. To further clarify the social and communicative relevance of this behavior, we recorded all occurrences of object use in a captive group (one adult male and four females) at Brasília Zoo, during 963 h of observation. Additionally, we recorded the occurrence of typical proceptive behaviors and quantified behavioral changes of the male associated with throwing behavior. All females threw objects, such as stones and sticks, at the male (N = 205 events). One of the females also pounded objects near the male (N = 72). The two forms of object use were associated with female proceptivity. Male-directed throws increased the chances of the male changing his behavior, particularly by shifting his attention to the thrower, supporting the hypothesis that throwing at the male function as a communicative act. However, females also used aimed throwing in affiliative contexts (N = 2) and interactions with humans (N = 102) and other animals (N = 61). Thus, our results show that aimed throwing is a flexible behavior, elicited in multiple social contexts and for different purposes. Moreover, our study demonstrates that considering the effects of object use on the behavior of potential targets can help us to understand how primates use objects to mediate communication. [ABSTRACT FROM AUTHOR]

Wild chimpanzee tool use is highly diverse and, in many cases, exhibits cultural variation: tool-use behaviours and techniques differ between communities and are passed down generations through social learning. Honey dipping – the use of sticks or leaves to extract honey from hives – has been identified across the whole species’ range. Nonetheless, there seems to be marked variation in honey dipping at a species level, with most descriptions originating from central Africa, and involving the use of complex tool sets, or even multifunctional tools. In West Africa, while honey consumption is common, in most cases tools are not used. We document, for the first time, the use of honey dipping tools in unhabituated chimpanzee (Pan troglodytes verus) communities at Cantanhez National Park (CNP), Guinea-Bissau. Over a 23-month period we employed a combination of direct (camera traps, n = 1944 camera trap days) and indirect (1000km of reconnaissance walks, collection of abandoned tools) methods to study four neighbouring communities in central CNP. Fluid dipping tools were found in three of the four communities; here we analyse 204 individual stick tools from the 70 tool-use ateliers found. In addition to documenting individual tool dimensions and raw materials, we adopt methods from primate archaeology to describe the typology of different tools based on use-wear patterns. We describe differences in tools used for different honey types, between communities, and tools and tool kits that show an unexpected degree of complexity. Our data also suggest the use of tool sets, i.e., tools with different functions used sequentially toward the same goal; as well as possible multifunction tools (pounding and dipping), never before described for western chimpanzees. Our study fills gaps in our knowledge of the wild chimpanzee cultural repertoire and highlights how chimpanzee tool manufacture and use can vary even at local scales.

Once considered only a human behavior, reports of tool use by a variety of animals have accumulated. Likewise, various definitions of tool use have also amassed. Although some researchers argue that understanding the evolutionary drivers of tool use is more important than identifying and describing these behaviors, the central issue of defining what constitutes tool use has not been fully addressed. Here we analyze prominent definitions of tool use and review the application of these definitions in scientific and educational literature. We demonstrate that many behaviors recently described as tool use do not meet criteria for prevalent definitions, while other neglected behaviors may constitute a form of tool use. These examples show how the use of inconsistent definitions of tool use in research can result in different conclusions from the same observations. Our aim is to demonstrate that a universally acceptable definition of tool use based on traditional, evolutionary, and operational understanding of behavior is needed. The rationale is that this review will stimulate the consistent and explicit use of specific terminology in tool use research. This would help define specific examples of each natural observation from a common measuring stick, allowing better comparative studies and classification of these unique behaviors.//

Behavioural innovations with tool-like objects in non-habitually tool-using species are thought to require complex physical understanding, but the underlying cognitive processes remain poorly understood. A few parrot species are capable of innovating tool-use and borderline tool-use behaviours. We tested this capacity in two species of macaw (Ara ambiguus, n = 9; Ara glaucogularis, n = 8) to investigate if they could solve a problem-solving task through manufacture of a multi-stone construction. Specifically, after having functional experience with a pre-inserted stick tool to push a reward out of a horizontal tube, the subjects were required to insert five stones consecutively from one side to perform the same function as the stick tool with the resulting multi-component construction. One Ara glaucogularis solved the task and innovated the stone construction after the experience with the stick tool. Two more subjects (one of each species) did so after having further functional experience of a single stone pushing a reward out of a shortened tube. These subjects were able to consistently solve the task, but often made errors, for example counter-productive stone insertions from the opposing end, even in some of the successful trials. Conversely, multiple trials without errors also suggested a strong goal direction. Their performance in the follow-up tasks was inconclusive since they sometimes inserted stones into un-baited or blocked 'dummy tubes', but this could have been an attention-deficit behaviour as subjects had not encountered these 'dummy tubes' before. Overall, the successful subjects' performance was so erratic that it proved difficult to conclude whether they had functional understanding of their multi-stone constructions. [ABSTRACT FROM AUTHOR]

Very few animals habitually manufacture and use tools. It has been suggested that advanced tool behaviour co‐evolves with a suite of behavioural, morphological and life history traits. In fact, there are indications for such an adaptive complex in tool‐using crows (genus Corvus species). Here, we sequenced the genomes of two habitually tool‐using and ten non‐tool‐using crow species to search for genomic signatures associated with a tool‐using lifestyle. Using comparative genomic and population genetic approaches, we screened for signals of selection in protein‐coding genes in the tool‐using New Caledonian and Hawaiian crows. While we detected signals of recent selection in New Caledonian crows near genes associated with bill morphology, our data indicate that genetic changes in these two lineages are surprisingly subtle, with little evidence at present for convergence. We explore the biological explanations for these findings, such as the relative roles of gene regulation and protein‐coding changes, as well as the possibility that statistical power to detect selection in recently diverged lineages may have been insufficient. Our study contributes to a growing body of literature aiming to decipher the genetic basis of recently evolved complex behaviour. [ABSTRACT FROM AUTHOR]

Objectives: Acquiring tool‐assisted foraging skills can potentially improve dietary quality and increase fitness for wild chimpanzees (Pan troglodytes). In contrast to chimpanzees in East and West Africa, chimpanzees in the Congo Basin use tool sets and brush‐tipped fishing probes to gather termites. We investigated the ontogeny of these tool skills in chimpanzees of the Goualougo Triangle, Republic of Congo, and compared it to that for chimpanzees at Gombe, Tanzania. We assessed whether chimpanzees acquired simple tool behaviors and single tool use before more complex actions and sequential use of multiple tool types. Materials and Methods: Using a longitudinal approach, we scored remote video footage to document the acquisition of termite‐gathering critical elements for 25 immature chimpanzees at Goualougo. Results: All chimpanzees termite fished by 2.9 years but did not manufacture brush‐tipped probes until an average of 4.3 years. Acquisition of sequential tool use extended into juvenility and adolescence. While we did not detect significant sex differences, most critical elements except tool manufacture were acquired slightly earlier by females. Discussion: These findings contrast with Gombe, where chimpanzees learn to both use and make fishing probes between ages 1.5–3.5 and acquire the complete task by age 5.5. Differences between sites could reflect tool material selectivity and design complexity, the challenge of sequential tool behaviors, and strength requirements of puncturing subterranean termite nests at Goualougo. These results illustrate how task complexity may influence the timing and sequence of skill acquisition, improving models of the ontogeny of tool behavior among early hominins who likely used complex, perishable technologies. [ABSTRACT FROM AUTHOR]

Capuchins can employ several strategies to deal with environmental challenges, such as using stone tools to access encapsulated resources. Nut-cracking is customary in several capuchin populations and can be affected by ecological and cultural factors; however, data on success and efficiency are only known for two wild populations. In this work, using camera traps, we assessed palm nut-cracking success and efficiency in two newly studied wild bearded capuchin populations ( Sapajus libidinosus ) and compared them with other sites. We tested the hypothesis that the overall success and efficiency of nut-cracking would be similar between sites when processing similar resources, finding partial support for it. Although using hammerstones of different sizes, capuchins had a similar success frequency. However, efficiency (number of strikes to crack a nut) was different, with one population being more efficient. We also tested whether success and efficiency varied between sexes in adults. We predict adult males would be more successful and efficient when cracking hard nuts. We found no differences between the sexes in one site but found sex differences in the other, although also for the low-resistant nut, which was unexpected. Our data add to the knowledge of capuchin nut-cracking behaviour flexibility, variance and potential cultural traits., Competing Interests: We declare we have no competing interests., (© 2024 The Authors.)

Technical reasoning refers to making inferences about how to use tools. The degree of technical reasoning is indicated by the bias of the gaze (fixation) on the functional part of the tool when in use. Few studies have examined whether technical reasoning differs between familiar and unfamiliar novel tools. In addition, what effect the intention to use the tool has on technical reasoning has not been determined. This study examined gaze shifts in relation to familiar or unfamiliar tools, under three conditions (free viewing, lift, and use), among 14 healthy adults (mean age ± standard deviation, 29.4 ± 3.9 years). The cumulative fixation time on the functional part of the tool served as a quantitative indicator of the degree of technical reasoning. The two-way analysis of variance for tools (familiar and unfamiliar) and conditions (free viewing, lift, and use) revealed that the cumulative fixation time significantly increased under free viewing and use conditions, compared to lift conditions. Relative to the free viewing condition, cumulative fixation time for unfamiliar tools significantly decreased in the lift condition and significantly increased in the use condition. Importantly, the results showed that technical reasoning was performed in both the use and the free viewing conditions. However, technical reasoning in the free viewing condition was not as strong as in the use condition. The difference between technical reasoning in free viewing and use conditions may indicate the difference between automatic and intentional technical reasoning.

Solving problems that are perceptually dissimilar but require similar solutions is a key skill in everyday life. In adults, this ability, termed analogical transfer, draws on memories of relevant past experiences that partially overlap with the present task at hand. Thanks to this support from long-term memory, analogical transfer allows remarkable behavioral flexibility beyond immediate situations. However, little is known about the interaction between long-term memory and analogical transfer in development as, to date, they have been studied separately. Here, for the first time, effects of age and memory on analogical transfer were investigated in 2–4.5-olds in a simple tool-use setup. Children attempted to solve a puzzle box after training the correct solution on a different looking box, either right before the test or 24 h earlier. We found that children (N = 105) could transfer the solution regardless of the delay and a perceptual conflict introduced in the tool set. For children who failed to transfer (N = 54) and repeated the test without a perceptual conflict, the odds of success did not improve. Our findings suggest that training promoted the detection of functional similarities between boxes and, thereby, flexible transfer both in the short and the long term.

It was thought that tool use in animals is an adaptive specialization. Recent studies, however, have shown that some non-tool-users, such as rooks and jays, can use and manufacture tools in laboratory settings. Despite the abundant evidence of tool use in corvids, little is known about the neural mechanisms underlying tool use in this family of birds. This review summarizes the current knowledge on the neural processes underlying tool use in humans, macaques and corvids. We suggest a possible neural network for tool use in macaques and hope this might inspire research to discover a similar brain network in corvids. We hope to establish a framework to elucidate the neural mechanisms that supported the convergent evolution of tool use in birds and mammals.

Successful computer use requires the operator to link the movement of the cursor to that of his or her hand. Previous studies suggest that the brain establishes this perceptual link through multisensory integration, whereby the causality evidence that drives the integration is provided by the correlated hand and cursor movement trajectories. Here, we explored the temporal window during which this causality evidence is effective. We used a basic cursor-control task, in which participants performed out-and-back reaching movements with their hand on a digitizer tablet. A corresponding cursor movement could be shown on a monitor, yet slightly rotated by an angle that varied from trial to trial. Upon completion of the backward movement, participants judged the endpoint of the outward hand or cursor movement. The mutually biased judgements that typically result reflect the integration of the proprioceptive information on hand endpoint with the visual information on cursor endpoint. We here manipulated the time period during which the cursor was visible, thereby selectively providing causality evidence either before or after sensory information regarding the to-be-judged movement endpoint was available. Specifically, the cursor was visible either during the outward or backward hand movement (conditions Out and Back, respectively). Our data revealed reduced integration in the condition Back compared with the condition Out, suggesting that causality evidence available before the to-be-judged movement endpoint is more powerful than later evidence in determining how strongly the brain integrates the endpoint information. This finding further suggests that sensory integration is not delayed until a judgement is requested.

Through the mechanisms of observation, imitation and teaching, young children readily pick up the tool using behaviours of their culture. However, little is known about the baseline abilities of children's tool use: what they might be capable of inventing on their own in the absence of socially provided information. It has been shown that children can spontaneously invent 11 of 12 candidate tool using behaviours observed within the foraging behaviours of wild non-human apes (Reindl et al. 2016 Proc. R. Soc. B 283, 20152402. (doi:10.1098/rspb.2015.2402)). However, no investigations to date have examined how tool use invention in children might vary across cultural contexts. The current study investigated the levels of spontaneous tool use invention in 2- to 5-year-old children from San Bushmen communities in South Africa and children in a large city in Australia on the same 12 candidate problem-solving tasks. Children in both cultural contexts correctly invented all 12 candidate tool using behaviours, suggesting that these behaviours are within the general cognitive and physical capacities of human children and can be produced in the absence of direct social learning mechanisms such as teaching or observation. Children in both cultures were more likely to invent those tool behaviours more frequently observed in great ape populations than those less frequently observed, suggesting there is similarity in the level of difficulty of invention across these behaviours for all great ape species. However, children in the Australian sample invented tool behaviours and succeeded on the tasks more often than did the Bushmen children, highlighting that aspects of a child's social or cultural environment may influence the rates of their tool use invention on such task sets, even when direct social information is absent.

The ability to think about and plan for the future is a critical cognitive skill for our daily life. There is ongoing debate about whether other animals possess future thinking. Part of the difficulty in resolving this debate is that there is not a definite methodology that allow us to conclude that animals (and human children) are truly thinking about a future event. Research with humans—both children and adults- will benefit the field of comparative psychology by providing information about the range of humans’ responses when they are faced with problems similar to those presented to other animals. Inspired by a problem that chimpanzees experienced in the wild, children of 4 and 5 years of age and young adults were presented with a situation in which they were expected to select two tools in order to obtain a reward. More older children than 4 years old successfully obtained the reward. Adults also succeeded at solving the problem. However, both children and adults struggled to select the two correct tools before any tool-use action was executed. While children’s performance is discussed in the context of temporal components required to envisage future events, adults’ performance is interpreted in the context of cognitive effort. These findings link developmental and adult cognition with comparative psychology.

Tool use is one of the most remarkable skills of the human species, enabling complex interactions with the environment. To establish such interactions, we predict the sensory consequences of our actions based on a copy of the motor command (efference copy), leading to an attenuated perception and neural suppression of the sensory input. Here, we investigated whether and how tools can be incorporated into these predictions. We hypothesized that similar predictive mechanisms are used for both hand and tool use actions, but that additional resources are needed to integrate the tool.During fMRI data acquisition, 19 healthy participants used either their right hand or a tool to hold the handle of a movement device. To manipulate the effect of the efference copy, the handle was moved either actively by participants or passively by the movement device. The sensory outcome, consisting of a real-time video of the hand or tool movement shown on a screen, was presented with varying delays (0–417 ms). Participants reported their perception of such delays.The processing of hand and tool movements yielded largely similar results when comparing active against passive conditions: Active movements were in both cases associated with worse delay detection performances. Moreover, during both hand and tool use actions, active movements led to a downregulation of sensory (somatosensory, visual) areas as well as the right cerebellum and right posterior parietal cortex, as assessed by a conjunction analysis. By contrast, an interaction analysis indicated differential processing of active vs. passive movements in hand vs. tool conditions in the left postcentral gyrus, right middle temporal gyrus (MTG), and bilateral caudate nuclei.Our findings provide behavioral and neural support that hand and tool actions share similar mechanisms for sensory predictions. We propose that the MTG and (sensori)motor areas (postcentral gyrus, caudate nuclei) contribute to these predictions by optimizing them to the physics of the end effector (hand or tool). Collectively, these results suggest that the brain dynamically adjusts sensorimotor predictive models to anticipate the dynamics of the end effector, be it a hand or a tool.

In captivity, the Goffin’s cockatoo (Cacatua goffiniana) has shown the capacity for flexible tool use and manufacture to a degree that rivals some habitually tool using birds. Although these skills make it an important avian model species for studying physical cognition, there are no scientific records of this species using objects as tools in the wild. We hereby report a single observation of a feral individual, showing an object related foraging behavior not previously described. The bird directly and repeatedly combined plant material (alternating between stiff stalks and flimsy leaves) with the inside of a foraging source (open coconuts) in a continuous and very persistent way. Here we analyze the observation and discuss how a psychological motivation for combining objects, particularly with food sources, may represent a potential new path to the onset of avian tool use. We evaluate the possibility that this particular case may already represent tool use and highlight the theoretical importance of this finding to our present state of knowledge about the technical abilities of this species.

Many primates show sex differences in behavior, particularly social behavior, but also tool use for extractive foraging. All great apes learn to build a supportive structure for sleep. Whether sex differences exist in building, as in extractive foraging, is unknown, and little is known about how building skills develop and vary between individuals in the wild. We therefore aimed to describe the nesting behavior of savanna chimpanzees (Pan troglodytes verus) in Fongoli, Senegal to provide comparative data and to investigate possible sex or age differences in nest building behaviors and nest characteristics. We followed chimpanzee groups to their night nesting sites to record group (55 nights) and individual level data (17 individuals) on nest building initiation and duration (57 nests) during the dry season between October 2007 and March 2008. We returned the following morning to record nest and tree characteristics (71 nests built by 25 individuals). Fongoli chimpanzees nested later than reported for other great apes, but no sex differences in initiating building emerged. Observations were limited but suggest adult females and immature males to nest higher, in larger trees than adult males, and adult females to take longer to build than either adult or immature males. Smaller females and immature males may avoid predation or access thinner, malleable branches, by nesting higher than adult males. These differences suggest that sex differences described for chimpanzee tool use may extend to nest building, with females investing more time and effort in constructing a safe, warm structure for sleep than males do. [ABSTRACT FROM AUTHOR]

Many animals, and an increasing number of artificial agents, display sophisticated capabilities to perceive and manipulate objects. But human beings remain distinctive in their capacity for flexible, creative tool use--using objects in new ways to act on the world, achieve a goal, or solve a problem. To study this type of general physical problem solving, we introduce the Virtual Tools game. In this game, people solve a large range of challenging physical puzzles in just a handful of attempts. We propose that the flexibility of human physical problem solving rests on an ability to imagine the effects of hypothesized actions, while the efficiency of human search arises from rich action priors which are updated via observations of the world. We instantiate these components in the "sample, simulate, update" (SSUP) model and show that it captures human performance across 30 levels of the Virtual Tools game. More broadly, this model provides a mechanism for explaining how people condense general physical knowledge into actionable, task-specific plans to achieve flexible and efficient physical problem solving. [ABSTRACT FROM AUTHOR]

Technical reasoning refers to making inferences about how to use tools. The degree of technical reasoning is indicated by the bias of the gaze (fixation) on the functional part of the tool when in use. Few studies have examined whether technical reasoning differs between familiar and unfamiliar novel tools. In addition, what effect the intention to use the tool has on technical reasoning has not been determined. This study examined gaze shifts in relation to familiar or unfamiliar tools, under three conditions (free viewing, lift, and use), among 14 healthy adults (mean age ± standard deviation, 29.4 ± 3.9 years). The cumulative fixation time on the functional part of the tool served as a quantitative indicator of the degree of technical reasoning. The two-way analysis of variance for tools (familiar and unfamiliar) and conditions (free viewing, lift, and use) revealed that the cumulative fixation time significantly increased under free viewing and use conditions, compared to lift conditions. Relative to the free viewing condition, cumulative fixation time for unfamiliar tools significantly decreased in the lift condition and significantly increased in the use condition. Importantly, the results showed that technical reasoning was performed in both the use and the free viewing conditions. However, technical reasoning in the free viewing condition was not as strong as in the use condition. The difference between technical reasoning in free viewing and use conditions may indicate the difference between automatic and intentional technical reasoning. [ABSTRACT FROM AUTHOR]

This study investigated tool use by the graphic tuskfish Choerodon graphicus in New Caledonia. Anvils included rocks, a conical shell, flat dead corals and a concrete mooring. Sixteen tool‐use events were observed in 10 h. A tool‐use event often involved more than one anvil (44%). On average, C. graphicus struck prey six times and spent 84 s at an anvil. The only prey items brought to anvils were bivalve and gastropod molluscs. These results provide a foundation for future research on tool use in fishes. [ABSTRACT FROM AUTHOR]

In the Ecological Approach to Perception and Action, affordances are emergent, higher-order relationships in an animal-environment system. In addition, perceivers should perceive such relationships directly, rather than by combining lower-order constituents of the affordance, such as non-affordance properties of the animal or the environment. In the present study, we investigated whether this latter claim applied to perception of superordinate affordances – affordances that emerge from relations between lower-order affordances. We asked whether perception of a superordinate affordance for reaching by different means would be reducible to a combination of lower-order constituents of that affordance. Participants reported the maximum height that they would be able to reach with their arm alone versus with a hand-held tool. In both cases, reported judgments of maximum reaching height differed from an additive model in which values were computed from a combination of perceived lower-order constituents of the affordance. The results are consistent with the ecological claim that affordances are perceived, "as such," rather than being computed or inferred from constituent properties, even when those constituent properties are, themselves, affordances. [ABSTRACT FROM AUTHOR]

Previous studies have shown that after actively using a handheld tool for a period of time, participants show visual biases toward stimuli presented near the end of the tool. Research suggests this is driven by an incorporation of the tool into the observer's body schema, extending peripersonal space to surround the tool. This study aims to investigate whether the same visual biases might be seen near remotely operated tools. Participants used tools—a handheld rake (Experiment 1), a remote-controlled drone (Experiment 2), a remote-controlled excavator (Experiment 3), or a handheld excavator (Experiment 4)—to rake sand for several minutes, then performed a target-detection task in which they made speeded responses to targets appearing near and far from the tool. In Experiment 1, participants detected targets appearing near the rake significantly faster than targets appearing far from the rake, replicating previous findings. We failed to find strong evidence of improved target detection near remotely operated tools in Experiments 2 and 3, but found clear evidence of near-tool facilitation in Experiment 4 when participants physically picked up the excavator and used it as a handheld tool. These results suggest that observers may not incorporate remotely operated tools into the body schema in the same manner as handheld tools. We discuss potential mechanisms that may drive these differences in embodiment between handheld and remote-controlled tools. [ABSTRACT FROM AUTHOR]

Theoretical views suggest that tool use and numerical magnitude processing can interact during prospective actions. For example, if a person intends to make a meal for several persons the next week, she/he will have to keep in mind during the homework-week large dish and large food portions for this event. Here, the magnitude 'large' can influence the future choice for large dishes and other related large tools. This study presents the first empirical evidence supporting this hypothesis. During a prospective memory task that implied to keep in mind a future action, participants were required to use a tool after processing Arabic numbers. Small (less than 5) and large (more than 5) magnitudes were employed as cues for the initiation of the tool-use task, which required participants to use inverse pliers with a small or a large object, but only for some prospective trials. The inverse pliers were used to dissociate the hand action from the tool action with the object (for example, opening the hand produced the closing action of the tool). The results revealed that during prospective trials, number processing interacted only with the tool action toward the object and not with the hand action. Specifically, after the processing of large magnitudes, the initiation of the closing action of the tool (i.e. the opening action of the hand) was reduced. This finding is discussed in the light of theories on the emergence of semantics through tool actions. [ABSTRACT FROM AUTHOR]

Solving problems that are perceptually dissimilar but require similar solutions is a key skill in everyday life. In adults, this ability, termed analogical transfer, draws on memories of relevant past experiences that partially overlap with the present task at hand. Thanks to this support from long-term memory, analogical transfer allows remarkable behavioral flexibility beyond immediate situations. However, little is known about the interaction between long-term memory and analogical transfer in development as, to date, they have been studied separately. Here, for the first time, effects of age and memory on analogical transfer were investigated in 2–4.5-olds in a simple tool-use setup. Children attempted to solve a puzzle box after training the correct solution on a different looking box, either right before the test or 24 h earlier. We found that children (N = 105) could transfer the solution regardless of the delay and a perceptual conflict introduced in the tool set. For children who failed to transfer (N = 54) and repeated the test without a perceptual conflict, the odds of success did not improve. Our findings suggest that training promoted the detection of functional similarities between boxes and, thereby, flexible transfer both in the short and the long term. [ABSTRACT FROM AUTHOR]

In line with the theory of event coding, many studies on tool use show that perceived visual and haptic information interacts with action execution. In two experiments, we investigated the temporal persistence of after-effects within an event file, and after-effects in temporally overlapping event files with the n-1 replication task. Each trial consisted of two phases: In phase 1, participants moved a cursor with a pen on a covered tablet while a gain varied the relation between hand and cursor amplitude (Experiment 1). In phase 2, participants replicated the hand amplitude of phase 1 of the previous trial without visual feedback. Any systematic over- and undershoot would be indicative for after-effects. When the cursor amplitude varied and the hand amplitude remained constant, we did not find any after-effects but adjustment of the internal model. For varying hand amplitudes, after-effects appeared in terms of a contrast and assimilation effect between temporally overlapping event files and within an event file, respectively. In Experiment 2, we confirmed that the observed pattern of over- and undershoots fully reflect assimilation/contrast due to perception-action interaction. The findings extend the current view on the temporal stability of short-term binding in sensorimotor transformation tasks: In the n-1 replication task, after-effects appeared only in trials with varying hand amplitudes. We replicated the contrast effect and assimilation effect, and the assimilation effect persisted for up to approximately 20 s. [ABSTRACT FROM AUTHOR]

It was thought that tool use in animals is an adaptive specialization. Recent studies, however, have shown that some non-tool-users, such as rooks and jays, can use and manufacture tools in laboratory settings. Despite the abundant evidence of tool use in corvids, little is known about the neural mechanisms underlying tool use in this family of birds. This review summarizes the current knowledge on the neural processes underlying tool use in humans, macaques and corvids. We suggest a possible neural network for tool use in macaques and hope this might inspire research to discover a similar brain network in corvids. We hope to establish a framework to elucidate the neural mechanisms that supported the convergent evolution of tool use in birds and mammals. [ABSTRACT FROM AUTHOR]