Pleasant, neutral, or unpleasant pictures were presented in a continuo
us series, and the effects of repetitive exposure to pictures of the s
ame affective valence were assessed in somatic (corrugator electromyog
raphic [EMG] activity) and visceral (heart rate and skin conductance)
systems. Probe stimuli (startle or reaction time probes) were presente
d to index emotional and attentional concomitants of processing. affec
tive discrimination was maintained across time in all response systems
, and sensitization was found for the corrugator EMG response. Respons
es to reaction time probes indexed differences in attentional allocati
on as a function of cognitive and affective variables in this paradigm
. Taken together, the data suggest that presentation of a series of af
fective pictures of similar valence produces emotional reactions that
are either maintained or sensitized across the temporal intervals used
here but that do not habituate.