Sam is a high school student who demonstrates behavioral problems when he is in the crowded school hallway, changing classrooms. As people bump into him and the noise from the others in the hallway gets louder, he becomes angry and often yells. At times he will begin punching those around him. It takes Sam time to calm down and he often misses part of his next class as he works on regulating his emotions. Which of the following best describes what is causing Sam's behavioral issues?