Valence-dependent modulation of psychophysiological measures: Is there consistency across repeated testing?

The present study used the picture perception paradigm to examine the exten t to which three well-documented psychophysiological measures demonstrate c onsistency across time in response to emotional stimuli. The three measures were the eye-blink startle response and the activation in two facial muscl e regions (zygomatic and corrugator). Twenty-seven young women were assesse d on two occasions, 2 weeks apart. Whereas activation in the corrugator and zygomatic muscle regions demonstrated the predicted patterns at both asses sments (with some attenuation in the zygomatic muscle regions), the startle response had limited consistency across the two assessments. The startle r esponse revealed the predicted linear pattern of valence modulation during the first assessment. During the second assessment, startle magnitude respo nse was a quadratic function of valence ratings and a linear function of ar ousal ratings. The unexpected pattern of startle response during the second session appeared to be related to the content of the pleasant slides, with action slides generating quadratic valence modulation and erotic slides co ntinuing to exhibit the expected linear valence modulation.