3.2.2.1. Emotion induction procedure. For the external mood induction we employed two 2-min videos to induce either positive or
neutral emotions. Videos were selected because a meta-analysis of
different mood induction procedures had identified this method as
most effective for mood induction (Westermann, Spies, Stahl, &
Hesse, 1996). For the neutral mood induction, participants viewed
a 2:13-min segment of Chillout (http://tinyurl.com/388buwc), a
video depicting flying birds and underwater marine life with a
soothing sound track. For the positive mood induction, learners
viewed the trailer of the movie Ice Age 3eDawn of the Dinosaurs
(http://tinyurl.com/8rsd3p), a 2:13-min segment where a sabertoothed squirrel named Scrat meets a girl and struggles to decide
between romance and his beloved acorn. These two videos were
pretested with a small sample of 10 participants from the same
population, and we found that they were able to induce the
intended neutral and positive emotional states.