Fig. 2.

Top panel Screenshots of the trial presentation employed in the computer-assisted DTT. On an “unprompted” trial (left), the sample stimulus is displayed at the top of the screen, and the three comparison stimuli are displayed in a horizontal row at the bottom of the screen. On a “prompted” trial (right), the two incorrect distracters are moved away from the bottom of the screen to facilitate correct responding on the trial. Bottom panel Photographs of the trial presentation employed in the teacher-assisted DTT. On an unprompted trial (left), the three comparison stimuli are displayed in a horizontal row closest to the student. On a prompted trial (right), the two incorrect distracters are moved away from the student to facilitate correct responding on the trial