Reaction Time

How would I go about having a final screen where I want to direct them to go get the experimenter. I want to the reaction time to be calculated as soon as the screen appears. In case they try pushing some random keys, I want the only key to be able to move on to be F10 - which will be pushed by the experimenter. I don't want the screen to be shown for more than 10 minutes. Is it possible to do all of this?

You could make the last item in your experiment an instruction item with password (x) parameter. E.g., (xcat) would cause MediaLab to wait until "cat" is typed before it would continue. Not sure what you mean by having the RT taken as soon as the screen appears--wouldn't that be 0ms?

Thanks, I'll try that.

I want the program to start counting the time elapsed as soon as the screen appears and I want to press a button so that the screen disappears and it calculates the total time elapsed.

What I want is for the screen to appear for 10 minutes unless the participant comes to get the experimenter where the experimenter would push a button and the screen will close - thus ending the experiment. This way the reaction time could vary between 0 and 10 minutes. Is this possible to do with your recommendation?

Yes, you could use an instruction screen with a (d600) parameter to have it up for 10 minutes (600 seconds) before continuing automatically to the end. The secret key sequence ctrl+right could also be used by the experimenter to end the item early at which time the actual exposure time would be recorded as of that moment. Does that help?