I have created a PPT activity featuring the Stroop Effect, which in psychology is a demonstration of the inability to correctly name the color of a word that is printed in a different color.
Use this activity as a warm-up or a filler, or tailor it to your needs.
I covered the answer slides with an opaque screen that will fade upon a click. Hopefully this will reduce the likelihood of students prematurely seeing the answers!
Enjoy!
Kim, S. (2010, May/June). Color Confusion. Neurology Now, 6(3)p.10.
American Academy of Neurology. "Color Confusion" by Kim, Scott. Retrieved 12 November 2014.
<http://patients.aan.com/resources/neurologynow/?event=home.showArticle&id=ovid.com:/bib/ovftdb/01222928-201006030-00007>.