Subjective effects of flicker light do not differ between open- and closed-eye viewing
James Thurbon, Annabelle Mitchell, Jordan J Wehrman, Vince Polito
Study at a glance
AI-extracted from the abstract| Characteristics | Preregistered mixed-design experiment |
|---|---|
| Sample size | 68 |
| Population | Adult participants (unspecified) |
| Interventions | 15 Hz audiovisual flicker Passive rest control |
| Duration | Two 10-minute tasks |
| Measures | visual imagery, altered consciousness, relaxation, skin conductance level (SCL) |
| Key findings | Eye condition did not affect subjective ratings of visual imagery, altered consciousness, or relaxation, but flicker increased skin conductance level and decreased relaxation compared with rest. SCL habituated logarithmically, with greater reductions when eyes were closed, and was unrelated to subjective measures. |
Abstract
Flicker light stimulation shows promise for inducing visual imagery, altered states of consciousness, and changes in arousal, with potential applications in relaxation and imagery-based therapeutic interventions. However, optimal utility depends on identifying how viewing conditions shape subjective and physiological outcomes. We examined whether eye condition (open, closed) modulates subjective and autonomic responses to 15 Hz audiovisual flicker. Methods. In a preregistered mixed-design experiment, 68 participants were assigned to eyes-open or eyes-closed conditions and completed two 10-minute tasks: a 15 Hz visual flicker with white noise and a passive rest control. Measures included visual imagery, altered consciousness, relaxation, and skin conductance level (SCL) as an index of physiological arousal. Results. Bayesian analyses supported no difference between eye conditions in ratings of visual imagery, altered consciousness and relaxation. Flicker increased SCL and decreased ratings of relaxation compared to control, however free reports indicated variable tension and relaxation responses. Across tasks and eye conditions, SCL exhibited a logarithmic habituation pattern. Greater reductions in SCL over time occurred for eyes closed compared to eyes open, however, SCL was not related to any subjective measures. Implications. Eye condition impacted the physiological but not phenomenological effects of flicker. Flicker protocols may be implemented flexibly across eye conditions without meaningfully altering subjective outcomes, supporting use in both experimental and applied settings. Relaxation during flicker may depend on individual characteristics. The logarithmic habituation of SCL suggests that autonomic responses to flicker diminish with continued exposure, which may inform stimulation duration in experimental and therapeutic applications.