I am running an experiment where I want to present picture stimuli for extremely short durations (as short as 1 refresh rate). In the event editor I have a 1 ms time limit for presentation so that the target appears for 1 refresh rate. I have found a discrepancy between black and white drawings and color photographs. The drawings seem to appear for longer on the screen than the color photographs. I have tried changing many things but I can not reverse this effect (I reduced the file size of the color images so that they would be similar to the drawings, I have tried out various forward and backward masks, put in ISIs of various lengths between the target and masks, moved each event into separate trials, turned on/off erasing the stimulus). Furthermore the drawing time Superlab claims for all of the images is less than a ms. Does anyone have any insight into why there would be such a difference? And how can I keep a consistent presentation time?
It would be interesting if this was a perceptual difference, but I have a feeling I am missing something with the technology.