Does word flickering improve reading? Negative evidence from four experiments using low and high frequencies

Abstract

Does word flickering facilitate reading? Despite a lack of scientific evidence, flickering glasses and lamps for dyslexia are being marketed in various countries. We conducted four experiments to assess their efficacy. Two experiments involved a computerized lexical decision task with constant display or low-frequency flickering (10 or 15 Hz). Among 375 regular adult readers, flicker noticeably slowed down word recognition, while slightly biasing the decision towards pseudowords. No significant effect was observed in 20 dyslexic children. In 22 dyslexic children, we also evaluated the impact of the Lexilight lamp and Lexilens glasses, which operate at higher frequencies, on reading fluency, letter identification and mirror letter processing. No detectable impact was observed. Lastly, in two participants who claimed to benefit from flickering glasses, we orthogonally manipulated whether the glasses were actually on, and whether the participant thought they were on. Only a small placebo effect was noted in one participant. Our findings starkly contrast with marketing claims that these tools can help 90% of dyslexics, and emphasize the role of rigorous scientific research in empowering dyslexic individuals to make informed decisions.

Comment on Le Floch & Ropars (2017) 'Left–right asymmetry of the Maxwell spot centroids in adults without and with dyslexia’

“…Meanwhile, independent evidence is starting to accumulate against the efficacy of stroboscopic manipulation. In a recent Proceedings of the Royal Society B paper, Lubineau et al reported negative evidence regarding impacts on reading from four experiments testing impact of flickering illumination: the flickering light emitted by the glasses and lamp were not found to help dyslexic readers, beyond a moderate placebo effect [19]. These findings are further supported by a recent preprint of Lapeyre et al that failed to identify any positive impact of pulsed lighting on the reading skills of adults with dyslexia [20].…”

“…In a recent Proceedings of the Royal Society B paper, Lubineau et al . reported negative evidence regarding impacts on reading from four experiments testing impact of flickering illumination: the flickering light emitted by the glasses and lamp were not found to help dyslexic readers, beyond a moderate placebo effect [ 19 ]. These findings are further supported by a recent preprint of Lapeyre et al .…”