TMT is strongly based on the work of behavioral economists like Daniel Kahneman, Amos Tversky, and Richard Thaler. Kahneman's 2011 book Thinking, Fast and Slow popularized the idea that people have two distinct mental systems. Two Minds Theory also draws heavily on the work of cognitive neuroscientists like Jonathan Evans and Keith Stanovich. Our version of Two Minds Theory differs from its predecessors in two key ways:
1. We propose that only the intuitive system operates fast enough to generate behavior. This differs in particular from Kahneman, who argues that the narrative system is "lazy" and usually inactive, but can become activated and take control of behavior away from the intuitive system. We instead suggest that the intuitive system is identical to Kahneman's "experiencing self" which functions in the moment, and that the narrative system is identical to Kahneman's "remembering self" which can only comment on experiences after they occur.
2. We propose that temporal immediacy is the most important differentiator between the two systems, with the intuitive system being activated whenever questions or situations are concerned with present experiences. The narrative system is activated when questions are asked about the past or the future. We suggest that many empirical findings, such as the gap that often occurs between people's intentions and their behaviors, can be explained based on this methodological feature.
Two Minds Theory is an adaptation of previous work in cognitive neuroscience, behavioral economics, and health psychology. The diagram below shows what happens when someone encounters a new situation (stimulus). Version 1 of the model, below, shows that two separate mental systems are set off at the same time:
The intuitive system registers perceptions about the stimulus, which trigger automatic responses and habitual responses that were stored in procedural memory. At the same time, the narrative system allows the person to make conscious judgments about the stimulus, leading to a conscious experience and then to narratives that take the form of propositions, attitudes, or beliefs which can be expressed in language. The narrative system also controls attention, which can be used to generate awareness of intuitive-level processes that are usually outside of consciousness.
Crucially, behavior is the result of the intuitive system's work only. This happens because the narrative system is simply too slow to generate behavior in the moment. But existing narratives (created and stored based on prior experiences with similar stimuli) do become part of the intuitive system's selection of behavior, in addition to immediate physiological reactions and previously learned responses. The exact mechanism by which the intuitive system selects behavior is still unknown, but it is tied to the real or imagined consequences that the behavior is projected to have. TMT proposes that selection of behavior happens outside of language and consciousness. In our view, the fact that behavior happens outside consciousness doesn't necessarily imply a philosophy of determinism.
The idea of "temporal immediacy," shown as a horizontal line between the Narrative and Intuitive systems in our original diagram, was intended to show the separation between narratives and intuitively-generated behaviors. The line isn't a barrier that can be crossed, simply because the Narrative system doesn't get involved until after the behavior occurs. Our original diagram is good for illustrating the operation of two independent systems, but the time element is hard to see -- really, the upper part of the diagram should be shifted about half a page to the right!
To address this point of confusion, CU Nursing PhD student Laurel Messer proposed the following alternative representation, which more clearly shows the time-delay inherent in the Narrative system:
In this second representation, the stimulus initially triggers an Intuitive system response, which includes both a reaction (perceptions, emotions, interpretations) and then a behavior. The intuitive response still occurs outside the level of consciousness, and the first two circles in this cycle (reading from the point where the stimulus comes in) correspond to the part below the line in version #1 of the theory. The behavior then leads to some immediate consequence (something not represented in version #1), which both teaches the Intuitive system what to do or avoid the next time around, and also becomes part of the resulting Narrative about the event.
Only after these things have all taken place does the Narrative system get to have its say. The Narrative response is something that the Intuitive system takes into account the next time it encounters a similar stimulus. This version of the diagram more clearly shows the "temporal immediacy" difference between the two systems -- the Intuitive System is fast and the Narrative System is slow. It also illustrates the futility of trying to talk oneself into a different behavior pattern, because conscious thought takes place after the behavior occurs. That's not to say a different way of thinking can't help, but it will help later, in future iterations of the cycle, and it will help only if it informs an Intuitive response that's below the level of consciousness. In other words, a new Narrative doesn't help unless you truly believe it "in your heart, in your gut, in your bones," as people say, and not just intellectually.
The intuitive system is based in subcortical areas of the brain:
The narrative system links to many brain areas, but is strongly dependent on activity in the prefrontal cortex. Our version of TMT suggests that the prefrontal cortex is not an "executive" in the sense of choosing or directing behaviors. Instead, it is more like a commentator that develops narratives based on behaviors as they occur. The prefrontal cortex connects to other brain areas that also support narrative thought:
Classical and medieval theories of mind posited a human soul with multiple parts:
Modern theories of mind also suggest multiple subsystems, only some parts of which are accessible to conscious thought:
We hope that Two Minds Theory is useful for helping the science of human behavior to advance. In particular, we hope that it will: