Figure 1

Impact of eye closure on current perception threshold (CPT). Electrical stimulation was applied to the right index fingers of 16 healthy subjects (10 females, mean age 23.1 ± 1.54 years). The thresholds were significantly decreased (higher sensitivity) when the eyes were closed in standard (normal environment light [right], paired t-test (2-tailed) p ≤ 0.004) and control (completely darkened room [left], paired t-test (2-tailed) p ≤ 0.001) conditions. A two-way ANOVA (to correct for inter-individual variance of the CPT, normalized CPT was calculated by dividing individual CPTs by the CPT in lights on / eyes opened) using two independent factors (lights on / darkness and eyes opened / closed) revealed a significant main-effect of eyes opened / closed and CPT (p ≤ 0.05). There was no significant main-effect for environment lights on / darkness and no significant interaction of eye state and environment. Error bars indicate the mean standard deviation. Please refer to Table 1 for individual results and group statistics.