What we experience as a decision may differ from what is actually happening in the brain, according to Tom James, a professor at Indiana University. His research challenges the traditional view that people first perceive information, then think, decide, and act in a fixed sequence.
For decades, scientific theories and everyday intuition have described decision-making as a series of separate steps. We perceive something, process the information, make a choice, and then produce an action. Each stage is often linked to a different brain function, progressing from sensory processing to cognition and finally to motor activity.
Many scientific approaches, including model-based cognitive neuroscience, are built around this linear framework. The model also reflects how decision-making feels from a first-person perspective. As James explains, “It feels like our actions are driven by decisions based on desires, beliefs, and intentions.”
Rethinking how the brain makes decisions
James argues that this popular explanation, often called the “sandwich model,” does not fully align with current scientific knowledge about the brain. Sensory experiences have identifiable sensory mechanisms, and physical actions have identifiable motor mechanisms. However, the cognitive stages supposedly positioned between sensation and action do not appear to involve distinct neural processes acting as an independent decision maker.
Instead of proposing a dedicated brain system that controls behavior, James suggests that sensory, sensorimotor, and motor processes work together to produce what he calls “action selection.” From this perspective, behavior emerges through ongoing interactions among the brain, body, and environment. These processes may happen simultaneously, continuously influence one another, and generate action without following a simple step-by-step sequence.
That does not mean James believes the concept of decision-making is meaningless.
As James says, “Of course they do. We use this language all the time, and it’s very useful in terms of describing behavior. I think the leap is that the brain works by having a decision-making or control process. The brain produces behavior that’s well-described that way. But it doesn’t need a process to make it look that way.”
James, a professor in the Department of Psychological and Brain Sciences in the College of Arts and Sciences, presented this argument in a paper titled “Sensorimotor Mechanisms of Decision-Making and Behavior,” published in the Journal of Cognitive Neuroscience.
What happens in the brain during decision-making?
James develops his argument through a “physicalist” framework associated with philosophers such as Daniel Dennett. This perspective reflects a fundamental assumption in science: physical phenomena can cause both physical and nonphysical phenomena, but nonphysical phenomena cannot independently cause physical events.
Sensory and motor processes are physical. In this framework, decisions are considered nonphysical descriptions of behavior. James therefore argues that a decision cannot literally cause a physical action in the same way that neural and bodily processes do.
To explain this idea, he uses several analogies.
Decisions as abstract explanations
Drawing on Daniel Dennett’s comparison of the self with a center of mass or center of gravity, James suggests that decision-making may function in a similar way. A center of mass is a useful mathematical concept, but it cannot independently exert physical force. You cannot move an object’s center of mass without moving the object itself.
In the same way, James proposes that a decision may be an abstract description of behavior rather than a physical entity that directly causes an action.
Another analogy illustrates how broad concepts can become less useful when researchers need to explain events in detail.
People commonly use the word “university” to describe the activities of an institution. The term conveniently refers to buildings, departments, employees, policies, and administrative processes. However, saying that “the university took action during campus protests” does not explain what physically happened. A detailed account might require examining meetings among administrators, calls to state police, and the actions of individual people.
James argues that decision-making creates a similar challenge for neuroscience. The concept can provide a useful high-level explanation of behavior without identifying the physical mechanisms that produce it.
James claims, “As mental phenomena, they are defined at too abstract a level to be the goal of cognitive neuroscience.”
In other words, knowing that a person made a decision does not, by itself, explain what occurred in the brain.
How a simple robot challenges traditional theories of decision-making
James extends his argument with a third example: a simple robot made up of a small number of sensory, motor, and sensorimotor modules.
The robot displays “wall-following” behavior that appears intentional. From an outside observer’s perspective, the machine seems to have a goal, a strategy, and perhaps even an intention.
Yet the robot does not contain a built-in system specifically designed to make decisions.
“Robots don’t have decision-making capabilities built into them,” James explains. “It just senses the environment and moves around accordingly. And based on the environment, it knows that following walls is a good thing. It looks intentional. It looks strategic. It looks like the robot is making a decision. But it actually isn’t. The reason we know that’s not the case is because there’s no system built into the robot to do that.”
This example raises important questions about human decision-making. If a relatively simple machine can produce behavior that looks intentional without a centralized decision-making system, could human behavior also appear to result from deliberate choices even when no single central process is responsible?
James argues that this explanation is more economical than assuming the brain contains “a high-level central controller that monitors and regulates sensory and motor processes.”
The problem with a central brain controller
The idea of a central controller also raises philosophical questions that have been debated since the time of René Descartes.
If a higher-level entity in the brain observes information and decides what to do, researchers must still explain how that controller itself operates.
“Explanations that the brain works through a central controller suggest that we don’t understand how the brain works, because we just put people inside the brain,” James says. “Dennett called this idea the Cartesian theater. That person in your brain needs another person in their brain, who needs another person in their brain, and so on, infinitely backward. So the problem is never solved; it’s just passed on.”
Rather than relying on an internal decision maker, James recommends studying the interacting sensory and motor systems that directly generate behavior.
How scientists may study decision-making in the future
If decision-making emerges from continuous interactions among the brain, body, and environment, researchers will need experimental methods capable of capturing that complexity.
James acknowledges that this approach presents both exciting opportunities and significant methodological challenges. Scientists may need to move beyond strictly linear models and examine brain processes that occur together, interact with one another, and change as people engage with their surroundings.
His laboratory has begun exploring this perspective by drawing on ideas from embodied cognition and ecological psychology.
James believes this approach could help cognitive neuroscience identify the mechanisms that produce what people describe as decisions. It may also offer new ways to study other cognitive and mental phenomena that have traditionally been treated as separate processes within the brain.
Source: www.sciencedaily.com