Your brain may not actually “make” decisions
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What we experience when making a decision may be very different from what actually happens inside the brain, according to Indiana University Professor Tom James.
For decades, both scientific theories and everyday intuition have tended to describe decision-making as a sequence. First we perceive something, then we think about it and make a choice, and finally we act. Each step is often assumed to correspond to a distinct brain function, moving from sensory processing to cognition and then to motor activity.
Many scientific approaches, particularly model-based cognitive neuroscience, are built around this same linear framework. It also matches how decision making feels from the inside. As James notes, “Our actions feel like they are caused by decisions based on desires, beliefs, and intentions.”
Rethinking the Brain’s Decision Making Process
James argues that this familiar explanation, sometimes called the “sandwich model,” does not fit neatly with what scientists know about the brain. Sensation has identifiable sensory mechanisms, and action has identifiable motor mechanisms. But the supposed cognitive stage between the two does not appear to have a corresponding neural process that functions as a distinct decision maker.
Rather than proposing a dedicated decision-making system that directs behavior, James suggests that sensory, sensorimotor, and motor processes together produce what he calls ‘action selection.’ In this view, behavior emerges through ongoing interactions among the brain, body, and environment. These processes can occur simultaneously and feed back into one another rather than unfolding as a simple sequence.
That does not mean James believes decisions are unreal.
As James says, “Of course they do. We use this language all the time and it’s very helpful in terms of describing behavior. The leap, I think, is to say that the brain works by having decision-making or control processes. It produces behavior that is well described in that way. But it doesn’t need a process that does that to make it look that way.”
James, a professor in the Department of Psychological and Brain Sciences in the College of Arts and Sciences, presents the argument in “Sensorimotor Mechanisms of Decisions and Actions,” an article just published in the Journal of Cognitive Neuroscience.
What Happens in the Brain When We Make a Decision?
James develops his argument using a “physicalist” framework associated with philosophers such as Daniel Dennett. The approach makes explicit what James sees as a basic assumption underlying science: physical phenomena can cause both physical and nonphysical phenomena, while nonphysical phenomena cannot themselves cause physical events.
Sensory and motor processes, for example, are physical. Decisions, in this framework, are nonphysical. If that is the case, James argues, a decision cannot literally cause a physical action.
To make the idea easier to understand, he uses several analogies.
Decisions as Abstract Descriptions
Drawing on Daniel Dennett’s comparison between the self and a center of mass (CoM) or center of gravity, James suggests that decisions may function in a similar way. A center of mass is a useful mathematical concept, but it cannot independently exert a physical force. (i.e., you cannot move an object’s center of mass without moving the object) In the same sense, James proposes that a decision may be an abstract description rather than a physical entity that directly causes something to happen.
Another analogy shows how useful concepts can become less informative when scientists need to understand events at a more detailed level.
We routinely use the phrase “the university” to describe the activities of an institution. The term conveniently represents a collection of people, buildings, departments, and processes. Saying that “the university took certain actions during a campus protest,” however, tells us little about the specific events involved. A detailed explanation might instead require examining meetings between administrators, phone calls to state police, and other individual actions.
James argues that decisions present a similar problem for neuroscience. They may provide a useful high-level description of behavior without revealing the physical mechanisms producing it.
As James maintains: “As mental phenomena, they are defined on too abstract a level for the goals of cognitive neuroscience.”
In other words, simply saying that someone made a decision does not explain what happened inside the brain.
A Simple Robot Raises a Bigger Question
James uses a third example to push the argument further.
He points to a robot constructed from a small number of sensory, motor, and sensorimotor modules. The machine demonstrates “wall-following” behavior that can appear purposeful. From the outside, it seems to have goals, strategies, and perhaps even something resembling intentions.
But the robot contains no system designed to make decisions.
“The robot does not have decisions built into it,” James explains. “It just senses its environment and moves around accordingly. And based on the environment, wall-following turns out to be a good thing. It looks intentional. It looks strategic. It looks like the robot is making decisions. And yet, it is not. The reason we know it is not is that there are no systems built into it to do that.”
That raises a provocative question. If a relatively simple machine can produce behavior that looks intentional without possessing a decision-making system, could human behavior also appear to result from centralized decisions even if no such central process exists?
James argues that this explanation is more parsimonious than assuming the brain contains what he calls “a higher-level, central controller that monitors and regulates sensory and motor processes.”
The Problem With a Central Controller
The idea of a central controller also creates a philosophical problem that has been discussed since the time of Descartes.
If some higher-level entity inside the brain is responsible for observing information and deciding what to do, scientists still need to explain how that controller itself works.
“Explaining that the brain works by way of a central controller suggests that you haven’t figured out how the brain works, because you’ve just put a person inside your brain,” says James. “Dennett called this idea the Cartesian Theater. That person inside your brain would need another person inside its brain, which would need a person inside its brain and so on, in an infinite regress. So the problem is never solved. It’s just passed on.”
Instead of invoking an internal decision maker, James proposes focusing directly on the interacting sensory and motor systems that generate behavior.
An Experimental Path Forward
If decision making emerges from continuous interactions among the brain, body, and environment, studying it will require experimental methods capable of capturing that complexity.
James acknowledges that this creates both exciting opportunities and difficult methodological challenges. Researchers would need to move beyond strictly linear models and examine processes that happen simultaneously, influence one another, and change as a person interacts with the surrounding world.
His own laboratory has begun exploring this direction by drawing on ideas from embodied cognition and ecological psychology.
James believes this approach could help cognitive neuroscience uncover the mechanisms that give rise to what we describe as decision-making. It may also offer new ways to investigate many other cognitive and mental phenomena that have traditionally been treated as distinct processes inside the brain.
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