Do emotional faces modulate pupillary pseudoneglect?

Pseudoneglect, a subtle attentional bias toward the left visual field in neurologically healthy individuals, can be measured with a split-screen method in which a bright stimulus in one hemifield elicits stronger pupil constriction when it appears on the left than on the right (Strauch, C., Romein, C., Naber, M., Van der Stigchel, S., & Ten Brink, A. F. (2022). The orienting response drives pseudoneglect-Evidence from an objective pupillometric method. Cortex, 151, 259-271. https://doi.org/10.1016/j.cortex.2022.03.006). Replications of this method have reported mixed results, including a large Registered Report that replicated the effect with a small effect size (d = -0.31). Given strong left-field biases in the emotional chimeric face test, the present study (n = 53) combined this task with split-screen pupillometry to test whether emotional face processing amplifies pupillary pseudoneglect. Pupillary pseudoneglect was observed during control trials with non-faces (d = -0.36) and was stronger for emotional faces (d = -0.76), but this difference was not significant. A strong left-field bias was confirmed for emotional face judgements (d = -0.76), which did not correlate with pupillary bias (ρ = -0.26), and for a line bisection test (d = -0.47), which also did not correlate with pupillary pseudoneglect (ρ = -0.19). These data support the split-screen pupillometric method for measuring pseudoneglect and replicate a previously-noted pattern that leftward biases across tasks show little statistical relation to one another.