Abstract
Introduction: The watercolor effect is a long-range color assimilation that appears to be related to luminance dependent color mechanisms in the cortex (Devinck et al. 2005). The present study used a chromatic pattern onset VEP to test whether physiological correlates to the long-range color assimilation produced by the watercolor effect can be found.
Methods: Pattern onset VEPs were recorded for two separate stimuli, one producing the watercolor assimilation, and one not. Both stimuli consisted of 1 cycle per degree (0.5° peak-to-trough amplitude) sinusoidal contour and flanker lines separated by 2.5 degrees of visual angle. For the non-assimilation stimuli, flanker lines were moved 0.5° away from contour lines.
Results: The negative CII component elicited from the assimilation condition was on average 20ms shorter than the CII component elicited by the non-assimilation condition. The CIII component also had consistently larger amplitude and shorter latency in the assimilation condition.
Conclusion: Changes in the components in the pattern-onset VEP waveform provide evidence for consistent physiological correlates of the long-range color assimilation produced with the watercolor effect.