3.2.2.4. Procedure. The procedure was in its entirety administered
through a computer system. Participants were tested in groups of
10e16 in a laboratory setting. Participants were randomly assigned
to one of the four groups, and each session lasted for about 1 h.
Participants received an introduction to the computer-based
procedures and were asked to follow the instructions on the
screen. After spending 5 min completing the demographic questionnaires, the participants were presented either the positive or the
neutral video in order to externally induce emotions. Participants
then completed the positive affect schedule for the first time (PAS1).
Next, the multimedia instruction with either neutral or positive
design of the material was presented to the participants on the
J.L. Plass et al. / Learning and Instruction 29 (2014) 128e140 131computer. Participants were told that they would be tested on the
content of the material after using the computer program and were
instructed to study the learning material for 15 min. Participants
were then given 25 min to complete the questionnaires of mental
effort and perceived task difficulty, the PAS for the second time
(PAS2), and self-report measure of intrinsic motivation, learning
performance (comprehension and transfer tests), perceptio