I have designed a cross-modal probe recognition study. My problem is, about 1/6 of my RTs are negative, and I don’t seem to understand why.
My trials consist in the following events:
- preCue (a “+” sign), presented until the participant presses a button (RT not recorded)
- Cue (another “+” sign), presented for 200 ms
- audio file, event to end “immediately after the event is presented”
- inter-stimulus interval (blank screen), presented for 1000 ms (RT non recorded, RT timer reset)
- probe (text, yes/no answer), presented until a response from the participant (RT recorded, RT timer reset)
The only recorded RT I am interested in is the last one, they are the only recorded. I exclude the participants are just answering before they see the probe, because accuracy is very high (>90%)
Has anyone else had this problem? Do you have any suggestions about what might be causing it?