running experimental trials

[Jeff]

the stopping condition for each trial occurs when either the ball falls off the end of the balance board or the time hits 20 seconds

You can use the viztask.waitAny command to wait until one of several conditions occurs. In your case these conditons would be a viztask.waitTime condition and a custom condition related to the ball's position.

The viztask documentation describes these commands and how to create a custom condition.