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

Daniel E. Bradford; Katherine P. Magruder; Rachel A. Korhumel; John J. Curtin

doi:10.3791/51905

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Method Article

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

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DOI:

10.3791/51905

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September 12th, 2014

Daniel E. Bradford^*¹ , Katherine P. Magruder^*¹ , Rachel A. Korhumel¹ , John J. Curtin¹

¹Department of Psychology, University of Wisconsin-Madison

^* These authors contributed equally

Summary

Potentiation of the startle reflex is measured via electromyography of the orbicularis oculi muscle during low (uncertain) and high (certain) probability electric shock threat in the Threat Probability Task. This provides an objective measure of distinct negative emotional states (fear/anxiety) for research on psychopathology, substance use/abuse, and broad affective science.

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.

Introduction

The overall goal of the Threat Probability Task is to experimentally disentangle the expression of anxiety in response to low probability (i.e., uncertain) threats from fear in response to high probability (i.e., certain) threats. Uncertainty occurs when some aspect of a threat is poorly defined. While anxiety can be described in numerous ways, exacerbated responses to low probability or otherwise uncertain negative events is a distinguishing clinical symptom in anxiety disorders^1,2. Furthermore, increased anxiety related physiological responding during uncertain threat of shock versus fear related physiological responding during certain t....