© 2004 Paul Cooijmans
This is a simple test for Mean Reaction Time (M.R.T.) and Reaction Time Standard Deviation (R.T.S.D., a measure of consistency in reaction speed). Both, R.T.S.D. even more than M.R.T., have a significant (though not high) negative correlation with "g", or general intelligence.
Push Start to begin. The yellow square will vanish and reappear after some time; Push Enter on your keyboard immediately when you see it reappear. Do not try to anticipate or push too early. After a series of 20 tests your scores will appear in the relevant fields.