Negative priming is conventionally defined by slowed responses to a ta
rget item that appeared previously as a distracter. As a result, it is
widely assumed that negative priming is caused by an act of ignoring.
Three experiments are reported in which novel abstract shapes were st
udied with either ''shallow'' or ''deep'' encoding instructions. This
study phase was followed by a same-different discrimination task simil
ar to that employed by DeSchepper and Treisman (1996). Same-different
discrimination was slower for old than for new target shapes, and this
negative priming effect depended on the difficulty of the discriminat
ion task. The results suggest that negative priming may not be caused
by the ignoring of a prime stimulus.