and unpleasant sounds were 7.02, 4.94, and 2.7, respectively, and mean arousal
ratings were 5.16, 4.59, and 6.94 for pleasant, neutral, and unpleasant sounds,
respectively, based on the IADS norms
1
(Bradley and Lang, 2000). Originally each
IADS clip lasted six seconds. Due to the silent-event related (SER) design that
required a stimulus’ duration of three seconds, we converted all selected IADS from
six to three seconds using Cool Edit Software (Syntrillium Software, now Adobe
Audition, Adobe Systems Inc., San Jose, California, USA). This adaptation of the
original stimuli was not statistically different from the original ratings for valence,
arousal and control dimensions of the 6-second sound in eleven normal volunteers
inside a mock MRI scanner (unpublished data).
In addition, the Self Assessment Manikin (SAM) scale, developed by Peter
Lang in 1980, was modified and applied in the present study. The original scale is
comprised of three parts, each consisting of nine options, to classify an emotional
stimulus, according to emotional valence, arousal and control dimensions of emotion
(Lang, 1980). Only the initial, middle and final figures of each part were chosen in
this experiment because of time constraints of the SER fMRI paradigm design and
button-type responses inside the MRI scanner. The modified SAM, according to the
emotional valence dimension, classified the sound as pleasant (happy manikin),
neutral (center’s manikin) and unpleasant (unhappy manikin) (figure 1A). The
second part of the modified scale classified the arousal dimension of emotion as
1
The IADS (Bradley &Lang, 1999) is available on CD-ROM, and can be obtained on request from
the authors at the NIMH Center for the Study of Emotion and Attention, BOX 100165 HSC,
University of Florida, Gainesville, FL 32610-0165, USA. IADS catalog numbers used in this study
are as follows: pleasant: 109, 110, 111, 112, 113, 151, 200, 201, 205, 220, 221, 226, 230, 270, 351,
352, 353, 370, 401, 601, 721, 724, 802, 810, 811, 812, 815, 816, 820, 826; neutral: 171, 251, 320,
322, 325, 410, 425, 500, 602, 700, 701, 704, 720, 722, 723; unpleasant: 106, 115, 116, 130, 252, 276,
277, 278, 279, 280, 285, 286, 290, 291, 292, 319, 380, 420, 422, 424, 501, 502, 600, 626, 698, 706,
709, 711, 712, 730. The numbers used to nominate the sounds are the original IADS numbers in order
to remain the same normative proposal of their study.