Psychological Research on Free Will Intuitions: A Critical Review

2. It's OK If 'My Brain Made Me Do It'

It's OK If 'My Brain Made Me Do It': People's Intuitions about Free Will and Neuroscientific Prediction
Eddy Nahmias, Jason Shepard, Shane Reuter
Cognition, Volume 133, Issue 2, November 2014, 502–16

Author's Abstract

In recent years, a number of prominent scientists have argued that free will is an illusion, appealing to evidence demonstrating that information about brain activity can be used to predict behavior before people are aware of having made a decision. These scientists claim that the possibility of perfect prediction based on neural information challenges the ordinary understanding of free will. In this paper we provide evidence suggesting that most people do not view the possibility of neuro-prediction as a threat to free will unless it also raises concerns about manipulation of the agent's behavior. In Experiment 1 two scenarios described future brain imaging technology that allows perfect prediction of decisions and actions based on earlier neural activity, and this possibility did not undermine most people's attributions of free will or responsibility, except in the scenario that also allowed manipulation. In Experiment 2 the scenarios increased the salience of the physicalist implications of neuro-prediction, while in Experiment 3 the scenarios suggested dualism, with perfect prediction by mindreaders. The patterns of results for these two experiments were similar to the results in Experiment 1, suggesting that participants do not understand free will to require specific metaphysical conditions regarding the mind–body relation. Most people seem to understand free will in a way that is not threatened by perfect prediction based on neural information, suggesting that they believe that just because "my brain made me do it," that does not mean that I didn't do it of my own free will.


Experiment 1: 278 Georgia State University undergraduates enrolled in critical thinking class (58% female, mean age 21.30)
Experiment 2: 213 Georgia State University undergraduates enrolled in critical thinking class (60% female, mean age 22.79)
Experiment 3: 196 Georgia State University undergraduates enrolled in critical thinking class (66% female, mean age 21.0)

The authors [Nahmias et al 2014: §1] begin their paper by providing an informative list of philosophical and scientific publications aiming to show that free will is an 'illusion' founded on false metaphysical presuppositions. The authors call these writers 'willusionists'.

Participants partaking in Experiment 1 were instructed that the scientists in the fictional scenario could not manipulate the decisions made by the character wearing the brain scanner cap. For this experiment, around 90% of participants agreed that the fictional character acted of her own free will [§2.2.2] and was morally responsible for her actions [§2.2.4]. The attribution of free will was very significantly less for the group receiving the instruction that the character's decisions were manipulated. Participants' attributions of free will and moral responsibility were slightly less in both these cases in Experiment 2, where the wording of questions made physicalism more explicit [§3.2.2 and §3.2.4].

Interestingly, using a bootstrap method for analyzing both Experiment 1 and Experiment 2 results, the authors found that the participants attributed free will in proportion to the fictional character's capacity to employ reasons for her action [§2.2.3 and §3.2.3]. Also confounding incompatibilists' theories was the finding that 80% or more of participants believed that such predictive technology was possible [§2.2.5 and §3.2.5]. For participants, how predictions were made was found to be not relevant. In Experiment 3, in which the brain scanner scenario was replaced with a mind reading scenario, participants were just as likely to attribute free will to the fictional character. Here, Experiment 3 replicated the results of the previous two experiments.

Book cover: The Free Will Delusion by James B. Mile

To forestall the objection that the participants did not fully understand the significance of perfect predictability in the given scenarios, the experimenters repeated statements emphasizing the 100% predictive accuracy of the scientists and the physicalist nature of the scenarios three times for each subject. In this and other respects, the experiments were well designed. Adding to the robustness of the methodology, the experimenters excluded from the test results those participants not passing an initial comprehension test and a final attention test. What I would like to see is these results replicated in a wider experimental cohort that reflects the demographics of the broader community. A cohort of young university students, as the authors themselves recognize [513], may not reflect accurately the use of 'free will' language by the general public.

This study provides sound empirical evidence against the incompatibilists' thesis. The results demonstrate to a high degree of confidence that people's attributions of free will are not dependent on an acceptance of a dualist metaphysics or an acausal view of mind. As the study authors [§5] conclude:

Our theory-lite view claims that most people think the existence of free will is compatible with multiple metaphysics of mind, including many forms of physicalism . . . What we hope to have accomplished here, in addition to arguing convincingly against the incompatibility of neuro-prediction and free will, is to provide initial evidence showing that people are more theory-lite than often assumed.

Importantly, this study bolsters the conclusion I reach in my essay, Free Will and Compatibilism [Allan 2016]. There, I show how the person on the street is metaphysically neutral in using 'free will' language and that incompatibilists burden unnecessarily the ordinary meaning of 'free will' and 'moral responsibility' with the indeterminists' metaphysical baggage.

robust methodology, but restricted demographics
Study results:
strongly supports compatibilism
strongly supports compatibilism

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