The study used two pieces of classical music: ‘Eine Kleine
Nachtmusik’ (Mozart) for positive mood induction and ‘The Planets
op.32 Venus’ (Holst) for neutral mood induction. These pieces were
selected due to the findings of Mitterschffthaler, Fu, Dalton, Andrew,
& Williams (2007) that ‘Eine Kleine Nachtmusik’ induced participants
into a happy mood and ‘The Planets op.32 Venus’ induced
participants into a neutral mood, both in terms of self reports of
emotional state and fMRI data. We used music as the method of
mood induction for a number of reasons: Firstly, it has proven to
be a reliable method in our previous research (Stafford et al., 2010)
and that of others (see review: Gerrards-Hesse, Spies, & Hesse, 1994).
Secondly, it has advantages over other methods that rely on asking
participants to recall positive events (i.e. Velten procedure), as such
methods carry an increased risk of demand characteristics. Finally,
since we were already using a video during the snack taste/intake
test (see section below ‘Film’), it seemed prudent to use a different
modality for mood induction.
Film
A video of the ‘Blue Planet: a natural history of the oceans
(episode 2 “The Deep”, BBC 2001)’was used whilst participants completed
the taste test. This procedure is similar to Yeomans and
Coughlan (2009) and was implemented so that participants would
feel more relaxed and less aware of the amount they were eating.
The music and video were played on an RM desktop computer
through stereo HD-3030 headphones via iTunes.