People’s belief in free will is lower when they need to urinate or desire sex

Embodied or grounded cognition is the name for the idea that physical states affect our thoughts and emotions. It's a controversial field, but typical findings include people's judgments of social closeness being shaped by room temperature, and their attentional style by the clothes they wear. A new paper takes things further, asking whether bodily states affect people's philosophical beliefs, specifically their belief in the notion of free will, defined and measured here in the lay sense of having self control and being in charge of one's actions (a typical questionnaire item was "I actively choose what to do from the options I have").

Michael Ent and Roy Baumeister began with an online survey of 23 people with panic disorder and 16 people with epilepsy. Compared with 35 healthy controls, individuals with these conditions believed that people in general have less free will (though their beliefs in their personal free will were no different from controls). The researchers acknowledged that the people with epilepsy and panic disorder may differ from controls in many ways other than their physical illness, but they believe this finding is consistent with their main thesis that having less control of one's body undermines belief in free will.

They further tested this idea with a second online survey of 81 more people (aged 18-70; 29 women), who were asked to rate their current state of needing to urinate, wanting sex, feeling tired, or hungry. People who felt any of these physical needs more strongly, except for hunger, tended to report lower beliefs in their own personal free will.

The anomaly of hunger was explained by a third and final survey with 112 more people, in which they were asked to report their hunger and also whether they were dieting. This time, if dieters were excluded from the analysis, feeling more hunger did go hand in hand with lower beliefs in personal free will. The researchers reasoned that for dieters, feeling hunger was actually a prime for stronger beliefs in free will, since their pangs were a sign they were successfully controlling their urges to eat.

Ent and Baumeister concluded that "embodiment may be a more far-reaching phenomenon than previous research has demonstrated" affecting not only people's views of the world and interactions with others, but also their abstract, philosophical beliefs. "Others have assumed that beliefs about free will are shaped by religious and political doctrines and logical reasoning," they said, "yet such beliefs are at least influenced by bodily cues as seemingly innocuous as a full bladder or an unfulfilled desire for sex."

Some may find these conclusions premature. This was not an experimental study, so rather than states of physical need being induced, they were entirely subjective. Of course physical need is a subjective experience, but the current methodology can't rule out the possibility that people with reduced beliefs in free will also tend to be more sensitive to their physical needs, or more happy to disclose them. In a similar vein, unmeasured factors such as mood or personality could be causally responsible for both greater sensitivity to one's physical needs and a reduced belief in free will. Unmeasured factors, such as differences in affluence and lifestyle, could also help explain the findings for people with epilepsy and panic disorder, without recourse to theories of embodied cognition.

Further reading

Embodied free will beliefs: Some effects of physical states on metaphysical opinions