Termination mid-trial

[michelle_jarick]

Hi,

I am trying to use a response window whereby after the participant must respond while a stimulus is displayed for 133ms (a red !). If the participant responds during this time, then I would like the trial to terminate and go to the next trial. However, if they do not respond within that duration of 133ms (while the red ! is displayed), then I would like the next stimulus in the trial to be presented (a black !) until a response is made, then proceed to the next trial. All of the trials in the experiment need to be random, so I cannot just tell the program to jump to a specific trial. Do you have any ideas of how I could do this?

Thanks!

[jarvis24]

You can have a sequence of stimuli within a trial, each with a RT being measured. You can use a max RT in your style file of "0-133!" which will cause DirectRT to continue on to the next stimulus in the sequence automatically after it's been up for 133ms. The trick is skipping out to the next trial if a response occurs. You can do this by using a skip value associated with the keypress. Say you are using the spacebar which is code 57. Use 57>-n, when n is the ID of the next trial. The negative value tells DirectRT to skip out immediately rather than waiting for the rest of the sequence to occur. You'll be able to check the RT data for all the items in your sequence in the log version of the data file. If you have any trouble with it, let me know.

-Blair