Tutorial: More Stim Per Trial (7/21)
Now that you've been through the fundamentals, we're ready to start adding some zest to our study. In this sample, you can see how you can use as many stimuli on a single trial as you need. For each stimulus, you simply add another set of Stim, Loc and Time cells to the trial row of your input file.
Check out the input file for this sample. Notice that it's very similar to the ones we were just using. The difference is that on trials 3-10, we've inserted two extra stimuli. Can you tell what these stimuli will look like?
First notice, that we inserted ~XXXXXXXXXX as the first stimulus for each of these trials. Since the ~ indicates that they actual text in the cell should be presented, the string of X's will appear in order to focus the subject's attention on where the next stimulus is about to appear. The time column tells DirectRT to display this stimulus for 500ms.
Next, we see an adjective as the next stim in the sequence for each trial. The adjectives also are preceded with ~ indicating that the text in the cell is the stimulus. The time column for the adjectives on each trial indicates the adjectives will appear for 100ms.
Finally, we see the final stim on each of these trials is $pic, which you saw in previous samples. Again, the $ symbol indicated that pic is a text file (pic.txt) listing stimuli from which DirectRT will draw randomly without replacement. In this case pic.txt again contains the names of image files. The time column for the pictures indicates the images will be displayed until a response key is hit, and that only the Z (code 44) or / key (code 53) will be considered valid.
Important: Note that you can have as many stimuli as you like on any given trial. The important thing to know is that, as always, you need to enter a * in the final cell of the row. This is a terminator, telling DirectRT you're done with that trial at that point.