Making stimuli disappear only when the 'correct' answer is given

[LEFT][FONT=Calibri][COLOR=#000000]Hi,[/COLOR][/FONT]
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[FONT=Calibri][COLOR=#000000]I'm trying to build an experiment and need to check if I can achieve what I need with DirectRT. [/COLOR][/FONT]
[FONT=Calibri][COLOR=#000000]At my experiment a stimuli is shown and participants should press one of 4 keys. One of those keys is the 'correct' key and I want the stimuli to disappear when it is being pressed. I also need the stimuli to be presented for a fix time and that the time passed between stimulus will be fixed as well. I have tried using the commends "full", "clear-1" and "-1" at the time column, and it seems I'm getting close but still have two critical problems that I don't know how to overcome:[/COLOR][/FONT]
[COLOR=#000000][FONT=Calibri][FONT=Calibri]1.[/FONT] [/FONT][FONT=Calibri]Can I make the stimuli disappear only when the 'correct' key is being pressed and not when the 3 other keys are being press?[/FONT][/COLOR]
[COLOR=#000000][FONT=Calibri][FONT=Calibri]2.[/FONT] [/FONT][FONT=Calibri]When a subject will press an 'incorrect' key and then the 'correct' key (before the fixed time as passed), it will seem at the results that he gave the TRUE response and I will not be able to see that he was actually wrong. Is there a way to present stimulus for a "full" time but collect and write to the results only the first key that is being pressed?[/FONT][/COLOR]
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[COLOR=#000000][FONT=Calibri]Waiting for your replay,[/FONT][/COLOR]
[COLOR=#000000][FONT=Calibri]Roy, [/FONT][/COLOR]
[COLOR=#000000][FONT=Calibri]Baruch's Lab manager[/FONT][/COLOR]
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