Recent studies have begun to challenge the notion of free will. Some people argue that free will exists, while others believe it may be a carefully constructed illusion. In order to better understand this concept, cognitive scientists have tried to study human agency by having subjects perform simple motions. One study identified the timing and activation of the brain regions that predetermine conscious intentions. A separate group of researchers focused on the sense of volition that precedes movement itself. In the following two studies, the experimenters use disparate methodologies and techniques to advance the study of individual autonomy.
Study 1:
Soon, Brass, Heinze, and Haynes aimed to elucidate the timing and location of brain region activation that predetermines conscious intention. The subjects were asked to press one of two buttons with either their right or left index finger whenever they felt the urge to do so. The experimenters flashed a series of letters on a screen at 500 millisecond time intervals to determine when the subject made his or her decision. After each finger motion, the subjects reported which letter was on the screen at the time when they made their decision, giving the experimenters a quantitative measure of when the subjects consciously decided. In addition to measuring the timing of the conscious decision, the scientists used fMRI to study the patterns and amount of activity in different brain regions. They looked at the predictive patterns both before and after the subject’s conscious decision.
Soon et al. found that two specific regions in the frontal and parietal cortex provided information that could predict the outcome of the motor decision before the subject was consciously aware of making that decision. They also discovered through the fMRI that unconscious activity in the brain had been affecting the subject’s motor decision for up to 10 seconds before the decision reached consciousness.
Study 2:
In a recent study, Schneider, Houdayer, Bai, and Hallett tried to determine when the sense of volition arises in movement formulation and execution. They used EEG signals to create a predictive model after asking subjects to move their right wrists spontaneously. They could determine with an 18% false positive rate when a person was going to move their right wrist within 1.5 seconds before the movement itself. The experimenters used the model for subsequent real-time prediction sessions. As the subjects moved their wrists during these sessions, they were stopped periodically and prompted to answer two questions: “Did you feel the intention to move?” and “If not, what were you thinking about?” A green light signalled subjects to answer the questions, providing a broad range of data because it turned on either spontaneously or when the predictive model explicitly showed a subject’s intention to move.
The responses to the first question were split into four categories to differentiate between the combinations of movement and intention. “Intention” refers to the intention to move as shown by the brain activity while using the predictive model. 43% were “movement with intention,” 13% were “movement without intention,” 12% were “no movement with intention,” and 32% were “no movement without intention.” The fact that 12% had the intention to move but did not end up moving may be a manifestation of free will because it displays the human capability to stop a movement, despite the brain’s supposed intention to move. There is not yet a conclusive explanation for this phenomenon. Additionally, the experimenters categorized the answers to the second question into subjects of thought which pertained to subjects like the task, light, or movement. The results showed that the participants could be thinking about something non-movement related, even while the brain was preparing to make a voluntary movement.
Study 1 and Study 2:
Both of these studies clearly show that voluntary movement can be predicted with reasonable accuracy using tools like fMRI and EEG. While they do conclusively address the idea that there are unconscious determinants that affect decisions, one shortcoming that pertains to them both is that they focus solely on simple motor movements. When people question the notion of free will, their concerns more closely relate to conscious, complex decision-making than to trivial finger and wrist motions. Focusing on simple motor movements is not enough to answer the loftier question about whether or not free will is really limited. Further research is required to better understand human autonomy and the existence of free will, particularly in the context of thoughtful deliberation.
Study 1:
Soon, Brass, Heinze, and Haynes aimed to elucidate the timing and location of brain region activation that predetermines conscious intention. The subjects were asked to press one of two buttons with either their right or left index finger whenever they felt the urge to do so. The experimenters flashed a series of letters on a screen at 500 millisecond time intervals to determine when the subject made his or her decision. After each finger motion, the subjects reported which letter was on the screen at the time when they made their decision, giving the experimenters a quantitative measure of when the subjects consciously decided. In addition to measuring the timing of the conscious decision, the scientists used fMRI to study the patterns and amount of activity in different brain regions. They looked at the predictive patterns both before and after the subject’s conscious decision.
Soon et al. found that two specific regions in the frontal and parietal cortex provided information that could predict the outcome of the motor decision before the subject was consciously aware of making that decision. They also discovered through the fMRI that unconscious activity in the brain had been affecting the subject’s motor decision for up to 10 seconds before the decision reached consciousness.
Study 2:
In a recent study, Schneider, Houdayer, Bai, and Hallett tried to determine when the sense of volition arises in movement formulation and execution. They used EEG signals to create a predictive model after asking subjects to move their right wrists spontaneously. They could determine with an 18% false positive rate when a person was going to move their right wrist within 1.5 seconds before the movement itself. The experimenters used the model for subsequent real-time prediction sessions. As the subjects moved their wrists during these sessions, they were stopped periodically and prompted to answer two questions: “Did you feel the intention to move?” and “If not, what were you thinking about?” A green light signalled subjects to answer the questions, providing a broad range of data because it turned on either spontaneously or when the predictive model explicitly showed a subject’s intention to move.
The responses to the first question were split into four categories to differentiate between the combinations of movement and intention. “Intention” refers to the intention to move as shown by the brain activity while using the predictive model. 43% were “movement with intention,” 13% were “movement without intention,” 12% were “no movement with intention,” and 32% were “no movement without intention.” The fact that 12% had the intention to move but did not end up moving may be a manifestation of free will because it displays the human capability to stop a movement, despite the brain’s supposed intention to move. There is not yet a conclusive explanation for this phenomenon. Additionally, the experimenters categorized the answers to the second question into subjects of thought which pertained to subjects like the task, light, or movement. The results showed that the participants could be thinking about something non-movement related, even while the brain was preparing to make a voluntary movement.
The results of Schneider et al. and Soon et al. each illuminated potential shortcomings that could have gone unnoticed had these articles not been read in conjunction with one another. The first questionable discrepancy pertains to the timing of the predictions. Soon et al. showed that the intention to move could be seen as far as 10 seconds before the movement itself. At successive points in time and, consequently, during different stages in motor planning, people could acquire varying types of information. Despite this finding, Schneider et al.’s predictive model only aimed to measure the intention to move 1.5 seconds in advance of an actual movement. By focusing solely on the last stages of motor planning, Schneider et al. does not provide as complete of an understanding of the brain activity leading up to movement as Soon et al. Reading Soon et al. makes the reader wonder if the results would have been different or if the predictive model would have been more accurate had the experimenters in Schneider et al. used information from more than 1.5 seconds before movement.
Additionally, reading Schneider et al. illuminated an assumption that is fundamental to Soon et al’s experimental design: the assumption that movement is always intentional. In “Unconscious determinants of free decisions in the human brain,” the possibilities of “movement without intention” or “no movement with intention” simply do not exist. The right and left index finger movements are always associated with an explicit “urge.” Reading Schneider et al. after Soon et al. highlights the important point that intention and movement are not always coupled.
Both of these studies clearly show that voluntary movement can be predicted with reasonable accuracy using tools like fMRI and EEG. While they do conclusively address the idea that there are unconscious determinants that affect decisions, one shortcoming that pertains to them both is that they focus solely on simple motor movements. When people question the notion of free will, their concerns more closely relate to conscious, complex decision-making than to trivial finger and wrist motions. Focusing on simple motor movements is not enough to answer the loftier question about whether or not free will is really limited. Further research is required to better understand human autonomy and the existence of free will, particularly in the context of thoughtful deliberation.
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