Aaron Schurger and Uri Maoz
The neuroscience of volition, to a large extent, investigates the neural precursors of conscious decision-making and action. Pupillometry is a powerful tool for investigating conscious and attentional processing, partly because of its connection to the locus coeruleus (Josh et al., 2016). For instance, in an attentional blink paradigm, differences in pupil dilations were associated with conscious versus nonconscious stimuli (Wierda et al., 2012). Nevertheless, this technique received little attention in the study of volition.
We collected pupil data during a spontaneous action paradigm, where subjects freely pressed a button at a time of their choosing, sometimes reporting their onset of movement or of intention using a clock (Libet et al., 1983). Preliminary analysis (N=12) demonstrated significant differences in baseline pupil size between conditions, potentially indicating cognitive load differences. Furthermore, replicating Richer and Beatty (1985), we found significant dilations before spontaneous movements. There were also indications that larger, pre-movement pupil dilations occur before reporting movement compared to before intention timing. These results support arguments that task demands, such as monitoring awareness, may affect the underlying neural activity leading to action and impact recorded signals—e.g., the readiness potential (Trevana and Miller, 2011). Moreover, these results offer a starting point for the use of pupillometry in studying conscious action production.
Harder, Kate M.; Moss, Ruby; and Gavenas, Jake, "Pupillometric Investigation of Spontaneous Action and Intention Awareness" (2020). Student Scholar Symposium Abstracts and Posters. 420.