Wednesday, November 26, 2014
Patience May Indicate Free Will
They say that patience is a virtue. It may also support the notion of free will. A person may defer action, as in pursuing a reward for example, because of a free choice to delay. This possibility lies at the heart of a new study in a long series of studies that began in the 1980s that have tested the notion that free will might not exist, that it is an illusion.
The prior experiments, widely interpreted to indicate that free will does not exist, demonstrated that neuron activity in a movement-control area of the cerebral cortex accelerated prior to a conscious decision to press a button. Thus, scientists interpreted this to mean the decision was made unconsciously, prior to the conscious realization that a decision had been made. I have challenged this interpretation on both grounds of the scientific methods used and misinterpretation of the cognitive neuroscience (see manuscript at www.ac-psych.org/download.php?id=84).
In this new study, Masayoshi Murakami and colleagues in Portugal, this electrical marker of decision-making was studied in rats in a different paradigm. Highly thirsty rats were trained to wait in place after hearing a sound cue until a second sound, a "go-for-it" sound was heard that would give them access to water. If the rats showed the required restraint, they received a larger water reward.
As the rats waited, the electrical "decision-making indicator" grew in magnitude and reached a threshold at the point where rats lost patience and went for the reward. The progressive increase in neural firing is interpreted as a well-known "integrate-and-fire" mechanism, wherein activity grows until a threshold for action is reached.
But they also found a second class of neurons whose firing could predict the rate at which the integrating neurons added up toward threshold. This observation of preceding regulatory control enabled a new interpretation of the original free will experiments on illusory free will. The "integrate-and-fire" population of neurons may not be making the actual decision, but rather reflecting an earlier decision-making processes elsewhere that regulate the integration toward action threshold.
Decision-making is complicated, even when it just involves pressing a button. I try to explain all this in my new book from Prometheus, "Mental Biology. The New Science of How the Brain and Mind Relate."
Murakami M, Vicente MI, Costa GM, & Mainen ZF. (2014) Neural antecedents of self-initiated actions in secondary motor cortex. Nature Neuroscience, 17(11), 1574-82. PMID: 25262496