Using the Threat Probability Task to Assess Anxiety and Fear During Uncertain and Certain Threat

Abstract

Fear of certain threat and anxiety about uncertain threat are distinct emotions with unique behavioral, cognitive-attentional, and neuroanatomical components. Both anxiety and fear can be studied in the laboratory by measuring the potentiation of the startle reflex. The startle reflex is a defensive reflex that is potentiated when an organism is threatened and the need for defense is high. The startle reflex is assessed via electromyography (EMG) in the orbicularis oculi muscle elicited by brief, intense, bursts of acoustic white noise (i.e., "startle probes"). Startle potentiation is calculated as the increase in startle response magnitude during presentation of sets of visual threat cues that signal delivery of mild electric shock relative to sets of matched cues that signal the absence of shock (no-threat cues). In the Threat Probability Task, fear is measured via startle potentiation to high probability (100% cue-contingent shock; certain) threat cues whereas anxiety is measured via startle potentiation to low probability (20% cue-contingent shock; uncertain) threat cues. Measurement of startle potentiation during the Threat Probability Task provides an objective and easily implemented alternative to assessment of negative affect via self-report or other methods (e.g., neuroimaging) that may be inappropriate or impractical for some researchers. Startle potentiation has been studied rigorously in both animals (e.g., rodents, non-human primates) and humans which facilitates animal-to-human translational research. Startle potentiation during certain and uncertain threat provides an objective measure of negative affective and distinct emotional states (fear, anxiety) to use in research on psychopathology, substance use/abuse and broadly in affective science. As such, it has been used extensively by clinical scientists interested in psychopathology etiology and by affective scientists interested in individual differences in emotion. Video LinkThe video component of this article can be found at

Psychometric properties of startle and corrugator response in NPU, affective picture viewing, and resting state tasks

“…To control for individual differences in shock sensitivity, we measured participants’ subjective tolerance using standard procedures from our laboratory (Bradford, Curtin, & Piper, ; Bradford, Magruder, Korhumel, & Curtin, ; Hogle et al, ). Participants rated a series of 200‐ms electric shocks of increasing intensity (7 mA maximum) administered to the distal phalanges of the second and fourth finger of the right hand.…”

“… We included mean general startle reactivity across both study visits (mean centered) as a covariate in the analyses of raw score startle potentiation/modulation measures to control for individual differences in raw startle response as recommended (Bradford, Kaye, & Curtin, ; Bradford, Magruder, Korhumel, & Curtin, ; Schmitz & Grillon, ). This covariate was unnecessary for standardized scores as the standardization procedure itself is designed to reduce individual differences.…”

If or when? Uncertainty's role in anxious anticipation

“…However, it does not seem that a greater number of shocks is always associated with greater startle blink responding. In fact, Bradford and colleagues (2014) showed that having more shocks (15) in a 100% probability condition produced less anticipatory startle responsivity than having fewer shocks (3) during a 20% probability condition with the number of trials held constant. These results, coupled with previous findings suggesting occurrence uncertainty and temporal uncertainty produce unique physiological and self-reported anxiety-related responses (Davies & Craske, 2015; Monat et al, 1972), suggest that the observed difference in startle responsivity between these two types of uncertainty is not due to the difference in the quantity of shocks.…”

“…Establishing the relative aversiveness of these various forms of uncertainty would inform understanding of the role each plays in the elicitation of physiological and subjective anxiety, as well as the development of both adaptive and maladaptive anxiety. A number of studies have experimentally manipulated the intensity and frequency of threat (Bradford, Magruder, Korhumel, & Curtin, 2014; Chin, Nelson, Jackson, & Hajcak, 2016; Dunsmoor, Bandettini, & Knight, 2007; Dunsmoor, Bandettini, & Knight, 2008; Hsu, Bhatt, Adolphs, Tranel, & Camerer, 2005; Marlin, Sullivan, Berk, & Miller, 1979; Monat, Averill, & Lazarus, 1972; Shankman et al, 2011; Williams et al, 2014). Shankman and colleagues (2011) found that temporal uncertainty and intensity uncertainty produced significantly larger startle responses than when the aversive stimulus was predictable in both conditions.…”

Empirically based comparisons of the reliability and validity of common quantification approaches for eyeblink startle potentiation in humans

“…We conducted offline data processing using the PhysBox plugin (Curtin, 2011) within the EEGLAB toolbox (Delorme & Makeig, 2004) in MATLAB (The Math Works Inc., Natick, MA). We followed published guidelines for startle response reduction and processing (Blumenthal et al, 2005;Bradford, Magruder et al, 2014). Specifically, we high-pass filtered (4th order 28 Hz Butterworth filter), epoched (250-250 ms surrounding probe), rectified, and smoothed (4th order 30 Hz Butterworth low-pass filter) the data.…”