The Use of Iambic Pentameter in the

search for the target in the experimental condition was inefficient. These results show that
participants could use pre-amodal completion information when displays were presented
for 100ms, but not when displays were presented for 200ms. This research was recently
further supported by fMRI evidence showing an incomplete, fragmented interpretation of
the prime at 100ms prime durations and an ambiguous interpretation of both the
completed shape and initial fragmented interpretation of the prime at 250ms prime
durations (Liu, Rauschenberger, Slotnick & Yantis, 2003).
The study of amodal object completion is in effect the study of a type of object
constancy, whereby the pre-constancy object image is the incomplete shape and the post-
constancy object image is the complete shape. If human perception of constancy can
change within time, it is reasonable to assume that human perception of perceptual
constancy in other domains might change across time as well. One such type of domain is
that of lightness and transparent filters.
Perception of lightness and transparent filters. Moore and Brown (2001) showed
that visual search processes do not simply involve post-constancy reflectance-based
information, but also can reflect pre-constancy retinal-based information. Participants
were shown displays that contained gray squares. A filter was placed in front of half of
each display so that any square that fell beneath it was reduced in luminance by 50%.
Experimental displays contained a light or dark square among medium distracters. The
light or dark gray square was the target. The target could appear inside or outside the
filtered area in one of 36 randomly selected locations on the stimulus. There were two
types of experimental displays: luminance-matched and luminance-unmatched. In
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