| dc.description.abstract | The startle blink reflex (SBR) is a well-validated measure of defensive emotional processing, particularly in picture viewing paradigms. Its magnitude is facilitated within 50 ms of picture onset, followed by an overall dampening of the reflex magnitude that slowly abates; furthermore, SBR is greater during aversive vs. pleasant pictures as soon as 1300 ms after picture onset. The time course of the modulation of the postauricular reflex (PAR), a promising measure of appetitive emotional processing, has yet to be established. We used 65 dB white noise clicks to elicit PAR during 6 s picture presentations in conjunction with standard 105 dB probes designed to elicit SBR , at 3, 4, or 5 s after picture onset. We found that SBR and PAR were both modulated in expected ways by the 105 dB probes, but only PAR was successfully elicited by the 65 dB clicks. In addition, PAR evidenced an early facilitation over the course of the first 500 ms of picture processing, followed by a slowly resolving inhibition. Moreover, click-elicited PAR was greater during pleasant vs. aversive pictures starting at 2000 ms after picture onset. | |
