Systematic Review of Studies on Subliminal Exposure to Phobic Stimuli: Integrating Therapeutic Models for Specific Phobias

Sergio Frumento; Danilo Menicucci; Paul Kenneth Hitchcott; Andrea Zaccaro; Angelo Gemignani

doi:10.3389/fnins.2021.654170

Systematic Review of Studies on Subliminal Exposure to Phobic Stimuli: Integrating Therapeutic Models for Specific Phobias

Front Neurosci. 2021 Jun 2:15:654170. doi: 10.3389/fnins.2021.654170. eCollection 2021.

Authors

Sergio Frumento¹, Danilo Menicucci¹, Paul Kenneth Hitchcott¹, Andrea Zaccaro¹, Angelo Gemignani^{1

2

3}

Affiliations

¹ Department of Surgical, Medical, Molecular and Critical Area Pathology, University of Pisa, Pisa, Italy.
² National Research Council, Institute of Clinical Physiology, Pisa, Italy.
³ Azienda Ospedaliero-Universitaria Pisana, Dipartimento di Specialità cliniche, Pisa, Italy.

Abstract

We systematically review 26 papers investigating subjective, behavioral, and psychophysiological correlates of subliminal exposure to phobic stimuli in phobic patients. Stimulations were found to elicit: (1) cardiac defense responses, (2) specific brain activations of both subcortical (e.g., amygdala) and cortical structures, (3) skin conductance reactions, only when stimuli lasted >20 ms and were administered with intertrial interval >20 s. While not inducing the distress caused by current (supraliminal) exposure therapies, exposure to subliminal phobic stimuli still results in successful extinction of both psychophysiological and behavioral correlates: however, it hardly improves subjective fear. We integrate those results with recent bifactorial models of emotional regulation, proposing a new form of exposure therapy whose effectiveness and acceptability should be maximized by a preliminary subliminal stimulation. Systematic Review Registration: identifier [CRD42021129234].

Keywords: anxiety disorders; desensitization; exposure therapy; masked; phobia; skin conductance; subliminal; unconscious.

Publication types

Systematic Review