About the task
Implements n-pair concurrent visual discrimination. The subject is presented with a series of pairs of stimuli; in each pair, one is correct (+) and one is wrong (-).
Configuring the task
| • | Maximum number of trials. When the subject has performed this number of trials, the task ends. (You may specify 0 for no limit, though you must specify a limit on the number of trials, the time, or both.) |
| • | Maximum time. When this time elapses, the task is terminated as soon as the current trial has finished. (You may specify 0 for no limit, though you must specify a limit on the number of trials, the time, or both.) |
| • | Finish when (X) of the last (Y) trials were performed correctly. I hope this is self-explanatory. |
| • | Response criterion time. If the subject fails make a response within this time, the subject fails the trial. (You may specify 0 for no limit.) |
| • | Time between trials. Specify a minimum and a maximum intertrial time (they may be the same). The actual time is chosen with a rectangular probability distribution within these values. |
| • | Leave correct stimulus on screen during reward. If unticked, all stimuli vanish when one is chosen. If ticked, then if the incorrect stimulus is chosen both vanish; if the correct stimulus is chosen, the incorrect stimulus vanishes and the correct stays for a while (while reward is being delivered). |
| • | Pairs. This lists the pairs in use. Each pair will have one correct stimulus (+) and one incorrect stimulus (-). Click Add or Remove to add or remove pairs. Click Toggle to swap round which of the pair is correct. |
| • | Pair choice method. Which pair will be used on any given trial? You may either have the program choose a pair at random, or quasi-randomly (such that each of the pairs appears once in every n trials, where n is the number of pairs). |
When you click Add to add a pair, you see the following dialogue box (just as a reminder):
Then this dialogue box appears twice, once for each stimulus to be chosen:
Screenshots from the task
A pair... The yellow one is correct.
If you wish, the correct stimulus can remain behind (during reward) if the subject chooses correctly.
Another pair.
