Stimulus Presentation (case 2158)

[avinash.avi010@gmail.com]

I want to present the stimulus for spcific time duration and next stimulus present only after the key response. But either the stimulus remains on screen till pressing the keys or it keeps on changing without pressing keys.

How to do this? Please offer the suggestions.

Avinash

[gerardo]

For a stimulus to be displayed for certain duration, write the time length in miliseconds under the time column. If you want the stimulus to display until a key is pressed, just specify the valid response under the time column instead.

For instance, for a flower to be displayed for 500 ms and a sun to be displayed until the spacebar is pressed:

stim | loc | time
flow |0,0,1| 500
sun |0,0,1| rt:57

[wcrescioni]

Hi Avinash. If I understand your problem correctly, you want to display one stimulus on screen for a set period of time, then have that stimulus disappear, and then present the next stimulus when the participant presses a key. Is that accurate? If so, I think I can help you with that. For your first stimulus, create an input file with your desired stimulus in the stim column of trial 1 and a time of X, where X is the amount of time you want that stimulus to remain on screen. In trial two, leave the stim column blank, then set your time column to rt:X, where X is they key you want subjects to press. Then trial three will present your next stimulus. The attached file illustrates this process using words as stimuli. "Stimulus 1" appears on screen for five seconds, then the screen goes blank. After pressing any key, the word "Stimulus 2" appears. The block then ends when any key pressed.