USAGE:Select an affect from the list, setting the beginning and ending intensity using the Begin and End select lists. Use the Append button to create sequences of expressions and run using the play button. Use the erase button to start over. The Preview button displays the selected affect without appending it to the play sequence.
Try each affect with Begin=1 and End=1 for its "startled" version!
(i.e., momentary duration with sudden onset).
Here's some additional background and references .