Quantifying the watercolor effect: from stimulus properties to neural models
Résumé
Visual illusions are perceptions that violate our expectations with respect to what we
understand about the physical stimulus, for example, surfaces of identical spectral
composition that appear to be of different colors. Such phenomena are thought to reveal
mechanisms, biases, priors or strategies that the brain uses to interpret the visual environment.
In natural viewing, we perceive all surfaces within a context of surrounding light and nearby
objects, and this context affects their appearance. Change in color appearance due to the
surrounding light is called color induction and can be of type contrast, when appearance of a
test region shifts in chromaticity away from that of the surround and assimilation when the
shift is toward that of the surround.
Pinna et al. (Pinna, 1987; Pinna et al., 2001) demonstrated a long-range, color
assimilation phenomenon called the Watercolor Effect (WCE) that provides an interesting
example for studying such processes. The WCE occurs when a wavy, dark, chromatic
contour delineating a figure is flanked on the inside by a lighter chromatic contour on a bright
background. The lighter color spreads into the entire enclosed area so that the interior surface
is perceived as filled in with a uniform color. Previous studies reported also a weak
coloration effect exterior to the contour (Cao et al., 2011; Devinck et al., 2005). The WCE is
distinguished from other assimilation illusions due by to its spatial extent; the phenomenon
has been reported to be observed over distances of up to 45 deg (Pinna et al., 2001). Here, we
review and discuss stimulus configurations, based on different procedures, that induce the
WCE and their implications for a neural model of this phenomenon.
Domaines
Ingénierie biomédicaleOrigine | Fichiers éditeurs autorisés sur une archive ouverte |
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