Emotion is conceived here as involving two motivational systems, appet
itive and defensive, that are organized in subcortical and deep cortic
al circuits that mediate reactions to primary reinforcers in mammals.
When activated by cues in the environment, these systems prompt widesp
read cortical, autonomic, and somatic responses that subserve adaptive
behaviors and direct attention. We present data from a picture percep
tion paradigm which indicate that processing affective pictures produc
es reliable patterns of psychophysiological response that support a ba
sic biphasic view of emotion.