Interstimulus timing

[sadler]

We are designing a cueing experiment with a visual search array. After presenting the fixation stimulus and the location cues, there is an ISI of 250 ms before presentation of the search array (which varies in number from 5 to 12). We have noticed when we actually run the file, the ISI is not 250 ms, but closer to 1000 ms. I realize that this is likely due to issues of drawing the array, but I need to overcome this and have an ISI of 250 ms. Any suggestions? I have attached the file.