Abstract
Critical flicker fusion threshold (CFFT) is the lowest level of continuous flicker that is perceived as a steady source of light and has historically been shown to be remarkably stable within and across multiple days of testing. The current study was designed to test the relationship between CFFT and subliminal learning. In two experimental groups, a total of seven participants were exposed to sub-contrast-threshold coherent dot motion occurring as a background feature of a rapid serial visual presentation (RSVP) task. Six other participants were recruited, and their CFFTs were recorded in the same manner as the experimental groups, either daily or during pre-test and post-test phases. Neural plasticity was instigated and measured with a Dynamic Random-Dot Display computer program. A Macular Pigment Densitometer was used to determine CFFT. Subjects reported the direction of coherent motion of random dot movement with 5% and 10% signal-to-noise ratio, and the direction of dot motion with 100% coherence of moving dots displayed at varying contrasts, sub-threshold through supra-threshold levels, in pre-test and post-test conditions. Herein we demonstrate that in subjects who underwent 1 hour of a subliminal motion training per day for nine days CFF thresholds increased significantly (by an average of 30%). This only occurred for subjects who experienced coherent motion paired with the targets of a task. Subjects who completed tasks without the motion pairing showed no improvement in CFFTs. These results demonstrate for the first time that the perceptual experience of subjects can dramatically alter CFFT and imply that CFFT is highly related to Dorsal Stream motion processing.
NSF 0418182, NIH R01 EY015980-01, Human Frontier Foundation RGP18/2004