For the unit on divided attention in my Cognitive Processes course, I created a demonstration in which half of the class is randomly assigned to text message each other while I lecture on time management strategies. The other half of the class does not text message during the lecture. Following the 10-minute lecture, all students complete a multiple-choice quiz. Results from 67 students over the past three semesters show that, in their proportion of answers correct, the Text condition performed statistically significantly worse on the quiz (M = .602, SD = .238) than did those in the No Text condition (M = .793, SD = .156), t (65) = 3.84, p < .001. This suggests that text messaging during lecture impairs comprehension of the material, which is consistent with the findings that people rely on inflexible memory systems while multi-tasking, which can impair learning (Foerder, Knowlton, & Poldrack, 2006), and that people lose time when switching from one task to another, especially when the tasks are complex or unfamiliar (Rubinstein, Meyer, & Evans, 2001).
Gingerich, Amanda C., "Multi-Tasking = Epic Fail: Students Who Text Message During Class Show Impaired Comprehension of Lecture Material" (2011). Scholarship and Professional Work - LAS. Paper 199.