# URGENT HELP!!! Stimulus Presentation Problem

Hi All,

I am conducting a priming experiment that involves the presentation of stimuli at 17milliseconds and 34 milliseconds. the stimuli comprises of African American and Caucasian faces. At such presentation speed (17 - 34ms), I should not be able to see the face at all, much less be able to make out whether the particular face presented is Black or White. The problem is that I am seeing the faces, and that is holding up the experiment.

Any suggestions??? Thanks in advance.

Take care about the refresh rate of the monitor…maybe you programmed 17 ms but the image is actually more than 17 ms on the screen due to the refresh rate.

If the refresh rate is 60 Hz, the minimum duration of an image on the screen is 16.6 ms, and the next possible duration 16.6 x 2 = 33.2 ms. Then if you programed 17 ms, maybe the actual duration is 33.2 ms.

Good luck!

In our experience when talking to researchers, at 34 and even 17 milliseconds, one would be able to tell if it is an African American or Caucasian face.