Context The belief that performing a nonlocal task in darkness plays a facilitating role in remote viewing and other psi-related phenomena is well established in esoteric and traditional beliefs (Grim, 1983; Hallowell, 1942; Lyon, 2012). However, the role of darkness in RV success is unclear beyond these esoteric explanations.

Objective This study explored the differential effect of darkness/light on remote viewing ability alongside the effect of time and their potential interaction.

Design From an initial sample of twenty, seven remote viewers contributed a total of nineteen sessions each (nine light/ten dark) which utilised randomized target selection, free-response descriptions, and ratings by both participants and an independent judge.

Results The usable data gave the edge to dark condition performance; the difference was not statistically significant. A statistically significant difference between remote viewer and independent judge raw scores attributed to the target image was identified (t (132) = 4.56, p <.001 (two-tailed) Mdiff = 14.21 [8.05, 20.4]) with a medium effect size (d = 0.40 [0.21, 0.57]). Exploratory post-hoc analyses concerning the numinosity of target images were conducted, to determine if this characteristic was associated with success. For numinosity ratings of target images, a mean difference of 11.24, 95% CI [0.12, 22.3] was shown as significant, with the target images of participant ‘hit’ sessions containing higher numinosity ratings than unsuccessful ‘miss’ sessions (t (11.47) = 2.22, p (two-tailed) = .048) with a large effect size (d = 1.02, [0.01, 1.99]).