This study examined how the presence of a visualized performance goal and reward displayed on computer programs affects tutors’ perception on the frequency and intensity of off-task behaviors (such as ‘out of seat’, ‘talking out’, ‘making noise’, and ‘’other) of students with learning difficulties. For this purpose, we collected data on the frequency and intensity of off-task behaviors based on the presence or absence of the visualized performance goal and rewards in a computer-based Korean phonics learning program. Tutors’ behavior ratings were compared to the ratings of a trained observer. This experiment was conducted while students with dyslexia received a series of Korean phonics instruction using a computer program in a 1:1 clinic setting. The results showed that regarding the behavior intensity, tutors reported higher scores on the ‘making noise’ when the performance goal was visually presented compared to when there was no performance goal presented. More importantly, tutors perceived that students showed more intense “talking-out” behaviors when the visualized performance goal and visualized reward were presented together. However, the trained observer reported that there was no significant difference in the intensity on students’ “talking out” behaviors when the performance goal and rewards were presented on the screen compared to when the goal and rewards were not presented. This study implies that the perceptions of educators regarding students’ negative behaviors during a computer-based instruction need to be delt with caution. The results also shed light on the need for related teacher training to promote positive interactions during computer-based instructions.