In a study, a few students did the number Stroop and color Stroop.
They showed much less interference on the numbers than they did on the color
task. Why does this make sense?
Please check these sites. If you post your answer, we'll be glad to comment on it.
http://www.snre.umich.edu/eplab/demos/st0/stroopdesc.html
http://faculty.washington.edu/chudler/java/readyn.html