Tool use is inherently about action. But action is largely missing from Osiurak and Reynaud's (O&R's) account of technical reasoning skills and the emergence of cumulative technological culture. We argue that a meaningful account of the rapid escalation of human tool use must include the action systems that are fundamental to the discovery, production, and cultural transmission of tools. Furthermore, we suggest that by incorporating action into explanations for the ascendance of human tool use, we can integrate technical reasoning and sociocultural approaches and thereby bridge this cognitive-sociocultural divide.
Our proposals are rooted in perception-action theory (Gibson Reference Gibson1979; Reference Gibson and Collins1982) and the protracted period of skill acquisition that characterizes motor development in human infants and children (Adolph & Robinson Reference Adolph, Robinson, Liben and Muller2015). From a perception-action perspective, objects, including tools, change the properties of the body's effectors (typically the hands and arms in humans). An object in hand can enrich or create new opportunities – “affordances” – for action (Adolph & Robinson Reference Adolph, Robinson, Liben and Muller2015; Lockman Reference Lockman2000); for example, empty hands do not easily afford hammering, but hard graspable objects do. Equally important, humans display exquisite, efficient exploratory procedures (Lederman & Klatzky Reference Lederman and Klatzky1987) to perceive which actions with which objects lead to which outcomes. Exploration enables people to discover an object's potential as a tool or the means to implement an existing tool. Information that specifies an object's potential to serve as a tool is often readily available in the environment and does not depend on the technical reasoning skills proposed by O&R. Even 8- to 10-month-old infants combine objects and environmental surfaces selectively based on the physical properties of each – a critical element for successful tool use (Fontenelle et al. Reference Fontenelle, Kahrs, Neal, Newton and Lockman2007). Similarly, other tool-using species, such as Capuchin monkeys (Visalberghi et al. Reference Visalberghi, Addessi, Truppa, Spagnoletti, Ottoni, Izar and Fragaszy2009a) and New Caledonian crows (Chappell & Kacelnik Reference Chappell and Kacelnik2002) explore and select tools geared to the demands of a given problem, thereby optimizing the outcome.
A developmental lens sheds further light on the process of tool use. Although information about an object's potential as a tool may be discoverable through exploratory procedures, successful tool use often requires extended periods of practice, especially early in development. In tool-using species such as chimpanzees, Capuchin monkeys, and New Caledonian crows, juveniles spend long periods of developmental time practicing action patterns that are subsequently incorporated into tool use (Inoue-Nakamura & Matsuzawa Reference Inoue-Nakamura and Matsuzawa1997; Kenward et al. Reference Kenward, Schloegl, Rutz, Weir, Bugnyar and Kacelnik2011; Resende et al. Reference Resende, Ottoni and Fragaszy2008). Similarly, human children spend several years hammering objects against other objects before they display the distinctively human pattern of controlled wrist flexion required for hammering accuracy (Kahrs et al. Reference Kahrs, Jung and Lockman2014). In short, the road to tool use entails much more than technical reasoning skills – motor skills must be refined; grips must be strengthened; and muscles and joints must be coordinated.
Perception-action exploration and motor skill learning are also fundamental to the discovery and implementation of actions when the affordance is not immediately apparent – that a lid twists, and it's necessary to turn to the left, not to the right. Such “hidden” affordances are common in artifacts – the required action is non-obvious but necessary to use the object as intended by the designer (Gaver Reference Gaver, Robertson, Olson and Olson1991; Rachwani et al. Reference Rachwani, Tamis-LeMonda, Lockman, Karasik and Adolph2020). Although technical reasoning may help to narrow the candidate affordances considered for further exploration, perceptual-motor activity is critical to discover and implement the designed actions of objects. A developmental lens is again instructive. When 11- to 37-month-old children are given containers that require a twist-off or pull-off action to open, the youngest children display non-designed actions such as banging or shaking; slightly older children attempt the designed action but frequently fail to open; and only the oldest children successfully implement the designed action (Rachwani et al. Reference Rachwani, Tamis-LeMonda, Lockman, Karasik and Adolph2020). Moreover, the lag between displaying a designed action and successful implementation extends for months or years. And so, technical reasoning alone does not ensure successful implementation. Children may know which action to perform, but knowledge does not guarantee success.
An action perspective can also enrich accounts of the mechanisms that promote sociocultural transmission of tool use. Our culture creates “user-friendly” tools and devices that advantage the morphology of the human hand and manual function. Thus, the designed affordances of human tools can shed new light on the ratcheting and social transmission mechanisms that underlie the growth of human technological culture across generations. Because the implementation requirements of many artifacts leverage the highly precise dynamics of fingers, hands, and arms (e.g., oscillatory dynamics of the arm are recruited to hammer; pressing actions of the fingers are engaged to type on a keyboard; pushing, pulling, and rotational movements of the hand/arm are enlisted to fit objects, plug in power cords, and so on), and because humans continually seek to modify artifacts to improve their fit with the constraints of the human body, the transmission of technology accelerates and ratchets up. Here, development again comes into play. The technological culture adapts tools to meet the limited skills of infants and children. Many cultures create smaller-scale replicas of tools and other artifacts for children (Lancy Reference Lancy2017). Similarly, changes in children's hand size and dexterity are the impetus to create developmentally appropriate artifacts to facilitate (e.g., easy-to-manipulate toys) or hinder (e.g., child-resistant packaging) young children's use of artifacts. And artifacts are modified to facilitate implementation in elderly people with diminished manual capacity. Collectively, these action-driven practices promote the transmission of human technological culture from one generation to the next.
To conclude, we agree with O&R's claim that the mechanisms that enabled transmission of human technological culture across generations are only incompletely understood. We argue that action must be the centerpiece of any account of human technological culture and observations of developmental change are instructive for understanding cultural change. An action-centered, developmental account can begin to bridge the cognitive-sociocultural divide in explanations of the discovery, production, and cultural transmission of human tool use.
Tool use is inherently about action. But action is largely missing from Osiurak and Reynaud's (O&R's) account of technical reasoning skills and the emergence of cumulative technological culture. We argue that a meaningful account of the rapid escalation of human tool use must include the action systems that are fundamental to the discovery, production, and cultural transmission of tools. Furthermore, we suggest that by incorporating action into explanations for the ascendance of human tool use, we can integrate technical reasoning and sociocultural approaches and thereby bridge this cognitive-sociocultural divide.
Our proposals are rooted in perception-action theory (Gibson Reference Gibson1979; Reference Gibson and Collins1982) and the protracted period of skill acquisition that characterizes motor development in human infants and children (Adolph & Robinson Reference Adolph, Robinson, Liben and Muller2015). From a perception-action perspective, objects, including tools, change the properties of the body's effectors (typically the hands and arms in humans). An object in hand can enrich or create new opportunities – “affordances” – for action (Adolph & Robinson Reference Adolph, Robinson, Liben and Muller2015; Lockman Reference Lockman2000); for example, empty hands do not easily afford hammering, but hard graspable objects do. Equally important, humans display exquisite, efficient exploratory procedures (Lederman & Klatzky Reference Lederman and Klatzky1987) to perceive which actions with which objects lead to which outcomes. Exploration enables people to discover an object's potential as a tool or the means to implement an existing tool. Information that specifies an object's potential to serve as a tool is often readily available in the environment and does not depend on the technical reasoning skills proposed by O&R. Even 8- to 10-month-old infants combine objects and environmental surfaces selectively based on the physical properties of each – a critical element for successful tool use (Fontenelle et al. Reference Fontenelle, Kahrs, Neal, Newton and Lockman2007). Similarly, other tool-using species, such as Capuchin monkeys (Visalberghi et al. Reference Visalberghi, Addessi, Truppa, Spagnoletti, Ottoni, Izar and Fragaszy2009a) and New Caledonian crows (Chappell & Kacelnik Reference Chappell and Kacelnik2002) explore and select tools geared to the demands of a given problem, thereby optimizing the outcome.
A developmental lens sheds further light on the process of tool use. Although information about an object's potential as a tool may be discoverable through exploratory procedures, successful tool use often requires extended periods of practice, especially early in development. In tool-using species such as chimpanzees, Capuchin monkeys, and New Caledonian crows, juveniles spend long periods of developmental time practicing action patterns that are subsequently incorporated into tool use (Inoue-Nakamura & Matsuzawa Reference Inoue-Nakamura and Matsuzawa1997; Kenward et al. Reference Kenward, Schloegl, Rutz, Weir, Bugnyar and Kacelnik2011; Resende et al. Reference Resende, Ottoni and Fragaszy2008). Similarly, human children spend several years hammering objects against other objects before they display the distinctively human pattern of controlled wrist flexion required for hammering accuracy (Kahrs et al. Reference Kahrs, Jung and Lockman2014). In short, the road to tool use entails much more than technical reasoning skills – motor skills must be refined; grips must be strengthened; and muscles and joints must be coordinated.
Perception-action exploration and motor skill learning are also fundamental to the discovery and implementation of actions when the affordance is not immediately apparent – that a lid twists, and it's necessary to turn to the left, not to the right. Such “hidden” affordances are common in artifacts – the required action is non-obvious but necessary to use the object as intended by the designer (Gaver Reference Gaver, Robertson, Olson and Olson1991; Rachwani et al. Reference Rachwani, Tamis-LeMonda, Lockman, Karasik and Adolph2020). Although technical reasoning may help to narrow the candidate affordances considered for further exploration, perceptual-motor activity is critical to discover and implement the designed actions of objects. A developmental lens is again instructive. When 11- to 37-month-old children are given containers that require a twist-off or pull-off action to open, the youngest children display non-designed actions such as banging or shaking; slightly older children attempt the designed action but frequently fail to open; and only the oldest children successfully implement the designed action (Rachwani et al. Reference Rachwani, Tamis-LeMonda, Lockman, Karasik and Adolph2020). Moreover, the lag between displaying a designed action and successful implementation extends for months or years. And so, technical reasoning alone does not ensure successful implementation. Children may know which action to perform, but knowledge does not guarantee success.
An action perspective can also enrich accounts of the mechanisms that promote sociocultural transmission of tool use. Our culture creates “user-friendly” tools and devices that advantage the morphology of the human hand and manual function. Thus, the designed affordances of human tools can shed new light on the ratcheting and social transmission mechanisms that underlie the growth of human technological culture across generations. Because the implementation requirements of many artifacts leverage the highly precise dynamics of fingers, hands, and arms (e.g., oscillatory dynamics of the arm are recruited to hammer; pressing actions of the fingers are engaged to type on a keyboard; pushing, pulling, and rotational movements of the hand/arm are enlisted to fit objects, plug in power cords, and so on), and because humans continually seek to modify artifacts to improve their fit with the constraints of the human body, the transmission of technology accelerates and ratchets up. Here, development again comes into play. The technological culture adapts tools to meet the limited skills of infants and children. Many cultures create smaller-scale replicas of tools and other artifacts for children (Lancy Reference Lancy2017). Similarly, changes in children's hand size and dexterity are the impetus to create developmentally appropriate artifacts to facilitate (e.g., easy-to-manipulate toys) or hinder (e.g., child-resistant packaging) young children's use of artifacts. And artifacts are modified to facilitate implementation in elderly people with diminished manual capacity. Collectively, these action-driven practices promote the transmission of human technological culture from one generation to the next.
To conclude, we agree with O&R's claim that the mechanisms that enabled transmission of human technological culture across generations are only incompletely understood. We argue that action must be the centerpiece of any account of human technological culture and observations of developmental change are instructive for understanding cultural change. An action-centered, developmental account can begin to bridge the cognitive-sociocultural divide in explanations of the discovery, production, and cultural transmission of human tool use.
Financial support
This work was supported by the National Institute of Child Health and Human Development (grant number R01-HD086034).
Conflict of interest
None.