Millisecond Forums

I am designing a backward conditioning experiment in which 4 faces are presented (in a within subject design) wherein 2 faces (one male one female) are paired with a threat stimulus (e.g., snake) and the other two faces (one male one female) are paired with a neutral stimulus. Each face is presented for 20 trials with the total trials being 80 (4 faces X 20 trials). However, as a cover story, participants are told to ignore the faces or any images by respond only to the last image that will be either a 'star' or a 'triangle'. They are basically instructed to respond as soon as possible using one of two keys assigned if they saw a star or a triangle on each trial. Of the 20 trials associated with each face, 10 trials will be "star" trials and the remaining 10 will be "triangle" trials. I am just not sure how to set up all these various conditions using the stimulustimes attribute. For one condition I was able to set it up as follows: