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Nothing to Fear but Fear Itself: A Mechanistic Test of Unconscious Exposure

Published:September 05, 2021DOI:https://doi.org/10.1016/j.biopsych.2021.08.022

      Abstract

      Background

      While effective, exposure therapy can be distressing, which creates problems with treatment acceptance. Can exposure be effectively delivered unconsciously—and thus without causing phobic people to experience distress? No study has tested this hypothesis in a sufficiently rigorous experiment that selected between mechanisms for reducing fear unconsciously.

      Methods

      We conducted a psychophysiological experiment of an unconscious exposure intervention to discern its mechanism of therapeutic action. We identified 98 highly spider-phobic participants with a validated fear questionnaire and a Behavioral Avoidance Test in which they gradually approached and exhibited impairment of a live tarantula, which was indicative of a DSM-5 diagnosis of specific phobia. These participants were randomized to viewing unconscious exposure to spiders, visible exposure to spiders, or unconscious exposure to flowers (control). In a novel psychophysiological design, concurrent changes in sympathetic arousal and subjective fear were monitored throughout exposure. Shortly thereafter, phobic participants approached the tarantula again in order to measure exposure-induced changes in real-life avoidance behavior and experienced fear.

      Results

      Unconscious exposure did not induce concurrent changes in sympathetic arousal or subjective fear, and subsequently reduced fear of the tarantula. Visible exposure to the same phobic stimuli, by contrast, induced significant arousal and fear, but did not affect fear of the tarantula. Levels of arousal during exposure moderated effects on fear of the tarantula: lower arousal during unconscious exposure, but not during conscious exposure, predicted greater fear reduction.

      Conclusions

      Unconscious exposure reduces fear by generating new implicit learning of nonaversive, stimulus-response associations that facilitate fear extinction in phobic persons.

      Keywords

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      References

        • Kessler R.C.
        • Berglund P.
        • Demler O.
        • Jin R.
        • Merikangas K.R.
        • Walters E.E.
        Lifetime prevalence and age-of-onset distributions of DSM-IV disorders in the National Comorbidity Survey Replication.
        Arch Gen Psychiatry. 2005; 62: 593-602
        • Wardenaar K.J.
        • Lim C.C.W.
        • Al-Hamzawi A.O.
        • Alonso J.
        • Andrade L.H.
        • Benjet C.
        • et al.
        The cross-national epidemiology of specific phobia in the World Mental Health Surveys.
        Psychol Med. 2017; 47: 1744-1760
        • Craske M.G.
        • Treanor M.
        • Conway C.C.
        • Zbozinek T.
        • Vervliet B.
        Maximizing exposure therapy: An inhibitory learning approach.
        Behav Res Ther. 2014; 58: 10-23
        • Hofmann S.G.
        • Smits J.A.
        Cognitive-behavioral therapy for adult anxiety disorders: A meta-analysis of randomized placebo-controlled trials.
        J Clin Psychiatry. 2008; 69: 621-632
        • Loerinc A.G.
        • Meuret A.E.
        • Twohig M.P.
        • Rosenfield D.
        • Bluett E.J.
        • Craske M.G.
        Response rates for CBT for anxiety disorders: Need for standardized criteria.
        Clin Psychol Rev. 2015; 42: 72-82
        • Gunter R.W.
        • Whittal M.L.
        Dissemination of cognitive-behavioral treatments for anxiety disorders: Overcoming barriers and improving patient access.
        Clin Psychol Rev. 2010; 30: 194-202
        • Zayfert C.
        • Deviva J.C.
        • Becker C.B.
        • Pike J.L.
        • Gillock K.L.
        • Hayes S.A.
        Exposure utilization and completion of cognitive behavioral therapy for PTSD in a “real world” clinical practice.
        J Trauma Stress. 2005; 18: 637-645
        • Siegel P.
        • Wang Z.
        • Murray L.
        • Campos J.
        • Sims V.
        • Leighton E.
        • Peterson B.S.
        Brain-based mediation of non-conscious reduction of phobic avoidance in young women during functional MRI: A randomised controlled experiment.
        Lancet Psychiatry. 2020; 7: 971-981
        • Taschereau-Dumouchel V.
        • Cortese A.
        • Chiba T.
        • Knotts J.D.
        • Kawato M.
        • Lau H.
        Towards an unconscious neural reinforcement intervention for common fears.
        Proc Natl Acad Sci U S A. 2018; 115: 3470-3475
        • Heeren A.
        • Reese H.E.
        • McNally R.J.
        • Philippot P.
        Attention training toward and away from threat in social phobia: Effects on subjective, behavioral, and physiological measures of anxiety.
        Behav Res Ther. 2012; 50: 30-39
        • Morris J.S.
        • Öhman A.
        • Dolan R.J.
        Conscious and unconscious emotional learning in the human amygdala.
        Nature. 1998; 393: 467-470
        • Morris J.S.
        • Öhman A.
        • Dolan R.J.
        A subcortical pathway to the right amygdala mediating “unseen” fear.
        Proc Natl Acad Sci U S A. 1999; 96: 1680-1685
        • Carlsson K.
        • Petersson K.M.
        • Lundqvist D.
        • Karlsson A.
        • Ingvar M.
        • Ohman A.
        Fear and the amygdala: Manipulation of awareness generates differential cerebral responses to phobic and fear-relevant (but nonfeared) stimuli.
        Emotion. 2004; 4: 340-353
        • Whalen P.J.
        • Kagan J.
        • Cook R.G.
        • Davis F.C.
        • Kim H.
        • Polis S.
        • et al.
        Human amygdala responsivity to masked fearful eye whites.
        Science. 2004; 306: 2061
        • Lipka J.
        • Miltner W.H.
        • Straube T.
        Vigilance for threat interacts with amygdala responses to subliminal threat cues in specific phobia.
        Biol Psychiatry. 2011; 70: 472-478
        • Williams L.M.
        • Das P.
        • Liddell B.J.
        • Kemp A.H.
        • Rennie C.J.
        • Gordon E.
        Mode of functional connectivity in amygdala pathways dissociates level of awareness for signals of fear.
        J Neurosci. 2006; 26: 9264-9271
        • Öhman A.
        • Soares J.J.
        “Unconscious anxiety”: Phobic responses to masked stimuli.
        J Abnorm Psychol. 1994; 103: 231-240
        • Esteves F.
        • Parra C.
        • Dimberg U.
        • Öhman A.
        Nonconscious associative learning: Pavlovian conditioning of skin conductance responses to masked fear-relevant facial stimuli.
        Psychophysiology. 1994; 31: 375-385
        • Öhman A.
        • Soares J.J.
        Emotional conditioning to masked stimuli: Expectancies for aversive outcomes following nonrecognized fear-relevant stimuli.
        J Exp Psychol Gen. 1998; 127: 69-82
        • Ruiz-Padial E.
        • Vila J.
        • Thayer J.F.
        The effect of conscious and non-conscious presentation of biologically relevant emotion pictures on emotion modulated startle and phasic heart rate.
        Int J Psychophysiol. 2011; 79: 341-346
        • Delgado M.R.
        • Nearing K.I.
        • Ledoux J.E.
        • Phelps E.A.
        Neural circuitry underlying the regulation of conditioned fear and its relation to extinction.
        Neuron. 2008; 59: 829-838
        • Phelps E.A.
        • Delgado M.R.
        • Nearing K.I.
        • LeDoux J.E.
        Extinction learning in humans: Role of the amygdala and vmPFC.
        Neuron. 2004; 43: 897-905
        • Siegel P.
        • Weinberger J.
        Very brief exposure: The effects of unreportable stimuli on fearful behavior.
        Conscious Cogn. 2009; 18: 939-951
        • Siegel P.
        • Anderson J.F.
        • Han E.
        Very brief exposure II: The effects of unreportable stimuli on reducing phobic behavior.
        Conscious Cogn. 2011; 20: 181-190
        • Weinberger J.
        • Siegel P.
        • Siefert C.
        • Drwal J.
        What you cannot see can help you: The effect of exposure to unreportable stimuli on approach behavior.
        Conscious Cogn. 2011; 20: 173-180
        • Siegel P.
        • Weinberger J.
        Less is more: The effects of very brief versus clearly visible exposure.
        Emotion. 2012; 12: 394-402
        • Siegel P.
        • Gallagher K.A.
        Delaying in vivo exposure to a tarantula with very brief exposure to phobic stimuli.
        J Behav Ther Exp Psychiatry. 2015; 46: 182-188
        • Siegel P.
        • Warren R.
        Less is still more: Maintenance of the very brief exposure effect 1 year later.
        Emotion. 2013; 13: 338-344
        • Norrholm S.D.
        • Glover E.M.
        • Stevens J.S.
        • Fani N.
        • Galatzer-Levy I.R.
        • Bradley B.
        • et al.
        Fear load: The psychophysiological over-expression of fear as an intermediate phenotype associated with trauma reactions.
        Int J Psychophysiol. 2015; 98: 270-275
        • Siegel P.
        • Warren R.
        • Wang Z.
        • Yang J.
        • Cohen D.
        • Anderson J.F.
        • et al.
        Less is more: Neural activity during very brief and clearly visible exposure to phobic stimuli.
        Hum Brain Mapp. 2017; 38: 2466-2481
        • Mayer B.
        • Merckelbach H.
        • de Jong P.J.
        • Leeuw I.
        Skin conductance responses of spider phobics to backwardly masked phobic cues.
        J Psychophysiol. 1999; 13: 152-159
        • Fyer A.J.
        Current approaches to etiology and pathophysiology of specific phobia.
        Biol Psychiatry. 1998; 44: 1295-1304
        • Magee W.J.
        • Eaton W.W.
        • Wittchen H.U.
        • McGonagle K.A.
        • Kessler R.C.
        Agoraphobia, simple phobia, and social phobia in the National Comorbidity Survey.
        Arch Gen Psychiatry. 1996; 53: 159-168
        • Szymanski J.
        • O’Donohue W.
        Fear of spiders questionnaire.
        J Behav Ther Exp Psychiatry. 1995; 26: 31-34
        • Williams J.M.
        • Mathews A.
        • Macleod C.
        The emotional stroop task and psychopathology.
        Psychol Bull. 1996; 120: 3-24
        • Dawson M.E.
        • Schell A.M.
        • Filion D.L.
        The electrodermal system.
        in: Cacioppo J.T. Tassinary L.G. Berntson G. Handbook of Psychophysiology. 3rd ed. Cambridge University Press, New York2007: 159-181
        • Benedek M.
        • Kaernbach C.
        A continuous measure of phasic electrodermal activity.
        J Neurosci Methods. 2010; 190: 80-91
        • Figner B.
        • Murphy R.O.
        • Siegel P.
        Measuring electrodermal activity and its application in judgment and decision-making research.
        in: Schulte-Mecklenbeck M. Kuehberger A. Ranyard R. A Handbook of Process Tracing Methods. 2nd ed. Psychology Press, New York2019: 158-180
        • Boucsein W.
        • Fowles D.C.
        • Grimnes S.
        • Ben-Shakhar G.
        • Roth W.T.
        • Dawson M.E.
        • et al.
        Publication recommendations for electrodermal measurements.
        Psychophysiology. 2012; 49: 1017-1034
        • Boucsein W.
        Electrodermal Activity.
        2nd ed. Springer, New York2012
        • Hofmann S.G.
        Cognitive processes during fear acquisition and extinction in animals and humans: Implications for exposure therapy of anxiety disorders.
        Clin Psychol Rev. 2008; 28: 199-210
        • Weisman J.S.
        • Rodebaugh T.L.
        Exposure therapy augmentation: A review and extension of techniques informed by an inhibitory learning approach.
        Clin Psychol Rev. 2018; 59: 41-51
        • Etkin A.
        • Wager T.D.
        Functional neuroimaging of anxiety: A meta-analysis of emotional processing in PTSD, Social Anxiety Disorder, and Specific Phobia.
        Am J Psychiatry. 2007; 164: 1476-1488