Researchers Bradley, Codispoti, Cuthbert and Lang wanted to further examine the emotional reactions in picture priming. Instead of using an appetitive stimulus they used stimulus sets from the International Affective Picture System (IAPS). The image set includes various unpleasant pictures such as snakes, insects, attack scenes, accidents, illness, and loss. They predicted that the unpleasant picture would stimulate a defensive motivational intensity response, which would produce strong emotional arousal such as skin gland responses and cardiac deceleration. Participants rated the pictures based on valence, arousal and dominance on the Self-Assessment Manikin (SAM) rating scale. The findings were consistent with the hypothesis and proved that emotion is organized motivationally by the intensity of activation in appetitive or defensive systems.