I am trying to program and Add-3 task where participants will see a string of 4 digits, have to add 3 to each digit, and then enter their response. I am using the openended trial for this, but want the participant to press 'ENTER' to enter their response (rather than using a mouse) because there will be many trials and I need it to go rapidly. If possible, I would also like to remove the button altogether. I have not been able to find a way to do that, and when I disable the mouse, even 'CTRL+RETURN' (which should work according to the Inquisit manual) does not work.
Any help would be appreciated!