Intertrial Interval

These settings specify what happens between trials during an experimental run.

When the “No intertrial interval” option is selected, there will be no pause or delay between the stimuli of consecutive trials.

When the “Use an intertrial interval” option is selected, you must specify the type of interval, and possibly a stimulus to present during the interval.

An intertrial interval can be a fixed time interval, or it can be experimenter-controlled length. If the interval is a fixed time, it will last the same amount of time (specify the length in ms), regardless of infant behavior. If the interval is *experimenter-controlled, the interval continues (the specified stimulus is displayed throughout) until the experimenter indicates that the subject is ready for the next trial (by hitting the <Space> key).

In either case, Habit can display a stimulus (commonly called an attention getter) during the intertrial interval, or can display just the background color. There is also an option to play a sound-only stimulus. Such a stimulus can be used with a beeping blinking box, which is a small device with a beeper and an LED light that beeps and flashes in a way that depends on the sound level of the stimulus. Here is a schematic for building such a device.

Figure 1: The Intertrial Interval dialog.