Dear e-primers,

I encounters a obstacle when programming an image experiment. Three images (A,B,C) are enrolled in trial with special alignment (like AB,BA,AA,BB,CC) where 800ms duration of stimuli of each image and 400ms interval is required. so, each unit (AB,BA,AA,BB,CC) will spend 2s.

I want to acquire experiment with following limits:

1. AB+BA=AA+BB=CC
  AB+BA，AA+BB，CC play randomly congruence probability and also is true for AB,BA and AA,BB (AB=BA, AA=BB)

2. interval of units(AB,BA,AA,BB,CC) is randomly assign with 2s average.

After beating my heaad against the wall and read the eprime help,I don't

know how to programe the experiment and sad.

Any assistance would be most appreciated!