I have a quick question.
In one phase of my experiment, a series of 20 faces are presented; each face is on the computer screen for 10 seconds and there is a 6 second inter-stimulus interval between each face. This has been easy to set up.
Now I am trying to have an attention probe (e.g., a red cross-hair) appear at a random time on each face; I then hope to record the participants’ reaction time to the onset of the probe. In other words, I want a red cross to appear on the forehead of each face stimuli at a random time in the 10 second period in which each face is shown. However, I do not know how to make the probe appear or how to set up the timing.
In case you are curious, I am doing this because half of the faces have direct eye gaze and half have averted eye gaze. I want to verify that participants are paying attention to both types of faces equally; ideally, they would respond to attention probes on the direct gaze faces as quickly as the respond to the attention probes on the averted gaze faces,
If anyone can help, I would be very appreciative.