Progressive time delay to remediate letter discrimination difficulty.

A b st r A c t reading is hindered when students have difficulty discriminating letters. given their visual similarity, the letters b and d can be challenging for some individuals. Progressive time delay (ptd) was used to teach two first-grade students to discriminate between the letters b and d. During the procedure, a problem was presented and a prompt immediately provided. As students correctly responded to the problem, the delay between the problem and the prompt was gradually increased. student 1 mastered the discrimination after four sessions and skills were maintained. student 2 showed gradual improvement but continued to make some errors. implications for practice are discussed.