Abstract
Critical flicker fusion (CFF) describes when quick amplitude modulations of a light source (i.e. flicker) become undetectable as the frequency of the modulation increases. The threshold at which CFF occurs has been shown to remain constant under repeated testing. The current study was designed to test the relationship between CFF and perceptual learning for motion. In experimental groups, subjects were exposed to sub-luminance-contrast-threshold coherent dot motion in which specific directions of motion were paired with characters of a rapid serial visual presentation (RSVP) training task, which has previously been shown to cause perceptual learning for motion (Seitz and Watanabe, 2003). In five-control groups, variations were made to the RSVP-training task or the luminance or coherence of the paired motion stimuli. On each day of training a Macular Pigment Densitometer was used to determine CFFT. Pre-training and post-training sensitivity tests were conducted with different directions of moving dots displayed at varying contrasts, sub-threshold through supra-threshold levels. Here we show that CFF thresholds increase by 30% in subjects who are trained in this procedure. The results of the control tasks demonstrate that changes in CFF thresholds are tightly coupled with improvements in discriminating motion stimuli and only individual subjects showing improvements in contrast-sensitivity showed significant changes in CFF thresholds. In addition, this CFF changes were long lasting and are retained for at least one year after training. We discuss how these results are highly suggestive of CFF plasticity being mediated by plasticity in low-level visual areas.
This research was supported by NSF grant (BCS-9905914), NIH grant (R01EY015980-01), and Human Frontier Research grant (RGP18/2004) and NSF (CELEST).