We tested whether motion and configural complexity affect perceived
transparency. A series of five coherent chromatic transformations in color
space was applied across a figure: translation, convergence, shear,
divergence and rotation. The stimuli consisted of a bipartite or a
checkerboard configuration (10 × 10°), with a central static or
moving overlay (5 × 5°). Three different luminance conditions
(the plane of chromatic transformation oriented toward higher, lower, or
equal luminances) were also tested for each of three modulation depths.
For each stimulus, the observer judged whether the overlay appeared
transparent or not. The main results indicated an interaction between the
type of chromatic transformation and stimulus motion and complexity. For
example, convergences are judged to appear transparent significantly more
often when motion is added for bipartite configurations, or when they are
generated in a checkerboard configuration. Surprisingly, shears that have
been reported to appear opaque, are more frequently reported to appear
transparent with short vector lengths and when combined with motion. Other
transformations are also affected by motion, although the effectiveness of
figural complexity on transparency seems to depend on both the type of
color shifts and the presence of motion. The results indicate that adding
motion and stimulus complexity are not necessarily neutral with respect to
the chromatic shifts evoking transparency. Thus, studies that have used
motion to enhance transparency may yield different results about the color
shifts supporting transparency perception from those that did not. The
same might be supposed for stimulus complexity under some conditions.