At times, the most straightforward inquiries prove to be the most challenging to unravel. Take, for instance, the decision-making process behind the simple act of wiggling your fingers. While the neural structures and muscles involved—the puppet and its strings—are well-documented, the question of who or what serves as the puppeteer remains a mystery.
Humans are creatures of intention, yet the mechanisms behind our transition into beings capable of deliberate actions—how we come to possess the power to effect change at will—remain largely unexplored. In an innovative study, we sought to uncover the origins of this sense of agency by observing infants as they discovered their own capacity to influence their surroundings. Our findings, published in the Proceedings of the National Academy of Sciences USA last September, mark the first time the development of agency has been mapped out, shedding light on those pivotal “aha!” moments and the circumstances that foster them.
For over half a century, a remarkably simple experiment has been a staple in the study of infant learning. Researchers place an infant in a crib beneath a hanging mobile. By attaching one end of a string to the mobile and the other to the infant’s foot, any movement by the baby results in a corresponding sway of the toy. This setup allows scientists to observe as infants grasp and remember a basic cause-and-effect principle: a kick results in the mobile’s movement.
In a recent iteration of this experiment, we aimed to pinpoint the exact moment when infants realize their movements can control the mobile. We engaged with 16 infants aged three to four months, employing advanced motion-capture technology to track the movements of both the infants and the mobile in three-dimensional space.
Previous experiments have shown that infants kick more when their foot is connected to the mobile than when it is not. However, it remained unclear whether the infants understood that their actions were the cause of the mobile’s movement. Given their inability to communicate verbally, we had to look beyond the obvious for explanations.
A significant clue emerged when an experimenter manually moved the mobile with the string. In these instances, infants kicked less than when the mobile was still, suggesting that their activity was not merely a reaction to the sight of the moving toy. Instead, our data indicated that it was the synchronized movement of the infant’s foot and the mobile that encouraged the baby’s activity.
Moreover, when the connection between the infant’s foot and the mobile was severed, the infants continued to kick vigorously, as if expecting the toy to react. This led some infants to display visible frustration when the mobile remained inert.
At some point during the experiment, the infants must have realized their control over the mobile, signifying their discovery of agency. To identify this moment, we developed an algorithm, dubbed our “aha! detector,” designed to identify spikes in foot movement. For some infants, a sudden increase in activity, marked by pauses and abrupt changes in speed, indicated their realization. These fluctuations are characteristic of complex systems on the cusp of change, from stock markets to brain activity.
Our observations also revealed a fascinating pattern: within the first minute of being tethered, infants would pause each time the mobile responded to their movements, creating a rhythmic sequence of action and pause. This behavior suggests that the infants were conducting their own experiments, learning the relationship between their actions and the mobile’s reactions.
Notably, not all infants responded in the same manner. This variance in behavior underscores the potential of our experimental setup and analytical approach to shed light on individual developmental trajectories, offering insights into both typical and atypical motor and cognitive development.
Our findings offer profound insights into the origins of agency. Several years ago, one of us (Kelso) proposed that agency’s emergence is a dynamic, self-organizing process. This theory suggests that there is no singular entity directing actions; instead, patterns and relationships evolve spontaneously in systems open to exchanges with their environment. Through our study, we observed that spontaneous movements transformed into purposeful actions once infants recognized their ability to influence the mobile. This realization marked the transition from random squirming to intentional movement, highlighting the critical role of the infant’s interaction with their environment in the emergence of goal-directed behavior.
This research not only advances our understanding of the development of agency but also contributes to the broader discourse on purpose and free will in living beings. By focusing on the relationship between an organism and its environment, we can begin to unravel the complex origins of directed behavior, moving beyond philosophical debates to a more nuanced understanding of how purposeful action arises.
In conclusion, our study underscores the importance of the dynamic interplay between an organism and its surroundings in the emergence of agency. As we continue to explore this fascinating frontier, we invite contributions and insights from the scientific community, aiming to further our understanding of the fundamental principles that govern our interactions with the world.