Restricting user input


I have an experiment which requires a ‘y’ or ‘n’ response from a participant. However, at the moment if the participant presses any other key, the next stimulus is presented. How can I restrict the input to just the y or n keys? (only one of these is the ‘correct’ response)

I could set the y and n key to both be correct responses, then restrict the input to ‘after a correct response from the participant’, but this would then not record if the participant response was correct or not. (hopefully that makes sense?!)

Thanks in advance!

Unfortunately, this is not a capability of SuperLab.