Escaping aversive exposure

Abstract

This research examined human defensive reactivity when exposure to an aversive event could be escaped but not entirely avoided. Prolonged visual cues indicated whether exposure to an upcoming aversive (i.e., disgusting) picture could be terminated after onset (escaped) or not, or that a neutral go signal would appear. Acoustically elicited startle reflexes were measured during each cue interval, as were cardiac and skin conductance activity. Early in the cuing interval, startle reflexes were potentiated during both escape and inescapable exposure trials, compared to the simple motor context. Later in the interval, reflexes remained potentiated for both escapable and inescapable trials, with potentiation further enhanced when aversive exposure could not be escaped compared to when exposure could be escaped. Heart rate deceleration in the cuing interval indicated increased vigilance when preparing any (escape or neutral) action, whereas skin conductance responding indicated enhanced sympathetic action mobilization particularly in an escape context. These data suggest that startle reflexes engaged in an escape context reflect both motor-related response inhibition and aversive potentiation, and they indicate that defensive motivation is engaged whenever aversive exposure is guaranteed, regardless of whether it can be escaped or not.

Extinction of Fear Memory Attenuates Conditioned Cardiovascular Fear Reactivity

“…Similarly, on both day 1 and 2 in the novel context we observed a initial brief decelerative HR response upon CS onset (Figures 1G,I ), which is likely parasympathetically mediated ( Iwata and LeDoux, 1988 ). This deceleration in HR is consistent with prior human fear research using HR (typically associated with fear responding) ( Lang et al, 2011 ; Sege et al, 2017 ). Taken together, these findings suggest that CS exposure in a novel context may elicit MAP and HR responses at different rates, with changes in autonomic regulation of HR first emerging upon CS onset (deceleration) and again when the conditioned stressor is removed (acceleration).…”

Avoidance and escape: Defensive reactivity and trait anxiety

“…Students scoring between 39 and 49 comprised a moderately anxious group (n = 25), with a maximum score of 39 chosen for the less anxious group (n = 25) because it corresponded to the median of the prior student sample and to research suggesting that a STAI score of 40 or above indicates elevated trait anxiety (Knight, Waal-Manning, & Spears, 1983). Sample sizes for each group were in line with a priori power analyses suggesting an optimal sample size of 25 per group (based on effect sizes from studies using similar methods; e.g., Hamm et al, 1997; Sege et al, 2017).…”

“…A total of 60 aversive images were selected from existing picture sets and supplemented with 10 images located by internet search. The choice of disgusting images as aversive stimuli was supported by eye movement research indicating that people routinely look away from disgust-related material (Ferrari, Codispoti, Cardinale, & Bradley, 2008), as well as by research that has successfully used such stimuli to study escape-related defensive reactivity (Sege et al, 2017). Additional stimulus information is included in the supplemental materials.…”

“…To the extent that defensive engagement when anticipating feared events is related to the certainty of eventual exposure, reflex potentiation and possibly other defensive markers (e.g., heart rate acceleration) should be enhanced in an escape, relative to avoidance, context, as suggested by data from previous studies (Löw et al, 2015; Wendt et al, 2016; Sege et al, 2017). On the other hand, because all participants are exposed to aversive scenes in the larger experimental context, defensive engagement may be similarly potentiated even when exposure is possible but not certain (i.e., in an avoidance context).…”

“…Though coping action completely blocks aversive exposure in some aversive contexts, in an escape context, action only shortens rather than prevents exposure. In a recent study in which a static cue signalled that an aversive picture that could be shortened but not eliminated (i.e., escaped but not avoided), reflex potentiation was found relative to a neutral motor context (Sege, Bradley, & Lang, 2017), suggesting that defensive engagement was not entirely eliminated. In the current study, we directly compared reactions when anticipated aversive exposure could be completely avoided or only escaped after initial onset, and compared reactivity in each of these coping contexts to reactivity when no coping response was available.…”