Resting heart rate variability and the startle reflex to briefly presented affective pictures.

We have previously shown that persons with low HRV showed potentiated startle responses to neutral stimuli. In the present study we replicated our prior findings and extended them to examine the effects of HRV on the startle magnitude to pictures that were presented outside of conscious awareness. A total of 85 male and female students were stratified via median split on their resting HRV. They were presented pictures for 6 s or for 30 ms. Results indicated that the high HRV group showed the context appropriate startle magnitude increase to unpleasant foreground. The low HRV group showed startle magnitude increase from pleasant to neutral pictures but no difference between the neutral and unpleasant pictures. This pattern of results was similar for the 30 ms and the 6 s conditions. These results suggest that having high HRV may allow persons to more efficiently process emotional stimuli and to better recognize threat and safety signals.