right response

I have four different response buttons for 4 different events, and only one button or a single key response must be correct. But when I press simultaneously the right one and one from the other 3 buttons, the response is also correct.:eek:

How can I hinder this?

SuperLab does not support multi-key responses. Each key press is treated as an individual response. As a result of this, pressing two buttons at the same time is not necessarily considered an incorrect response.