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Paul Siegel

Professor of Psychology

I am a clinical psychologist who fully believes in the scientist-practitioner tradition: research on mental illness and clinical practice should mutually inform each other. My areas of expertise are psychopathology – the scientific study of mental illness and abnormal behavior, clinical psychology, and emotion. I am especially interested in unconscious processes in emotion, which has become a converging focus in psychopathology.  That our emotional life has unconscious origins is now well established. Psychopathology is a revealing window into unconscious emotion processes because when behavior is not adaptive, it reveals its underlying mechanisms.

Research Interests

My translational research program is testing a clinical implication of emotional neuroscience, which has shown that fear responses can be activated and acquired without conscious awareness. Very brief exposure (VBE) is the presentation of a continuous series of masked – unrecognizable - phobic images to reduce fear. A series of experiments conducted in my lab have shown that VBE reduces avoidance and experienced fear of a live tarantula by spider-phobic participants without causing them to experience fear consciously. A recent study found that VBE has similar fear-reducing effects on highly socially anxious persons. These findings challenge the prevailing clinical belief that a person must directly confront a feared object or situation in order to reduce fear of it.  

With the support of an R21 Research Grant from the National Institute of Mental Health, and a NARSAD Young Investigator Award from the Brain and Behavior Research Foundation, I am conducting fMRI studies of the neurobiological basis of VBE. My collaborator on this research is Dr. Bradley Peterson, Director of the Institute for the Developing Mind, and Chief of Child and Adolescent Psychiatry at Children’s Hospital Los Angeles and the University of Southern California.

Representative Courses

Abnormal Psychology

Developmental Psychopathology


Since 2009

Siegel, P., Cohen, B., & Warren, R. (2022). Nothing to fear but fear itself: A mechanistic test of unconscious exposure. Biological Psychiatry, 91(3), 294-302.

Siegel, P. & Peterson, B.S. (2022). What you don’t know can help you: An activating placebo effect in spider phobia. Behavior Research and Therapy, 149, 103994.

Siegel, P. & Peterson, B.S. (2021). An opportunity for multivariate pattern analysis in psychiatry. The Lancet Psychiatry, 8(2), 99-100.

Siegel, P., Wang, Z., Murray, L., Campos, J., Leighton, E. & Peterson, B.S. (2020). Brain-based mediation of the non-conscious reduction of phobic avoidance during fMRI: A randomized controlled experiment. The Lancet Psychiatry, 7(11), 971-981.

Siegel, P., Selvaggi, S., Sims, V., & Rinck, M. (2019). Social anxiety elicits an approach mere exposure effect for angry faces. Psychology of Consciousness 7(1), 30-45 (APA journal).

Figner, B., Murphy, R. O., & Siegel, P. (2018). Measuring electrodermal activity and its applications in judgment and decision making research. In M. Schulte-Mecklenbeck, A. Kuehberger, & R. Ranyard (Eds.), A handbook of process tracing methods for decision research (p. 163-184). New York, NY: Psychology Press.

Siegel, P., Warren R., Wang, Z., Yang, J., Cohen, D., Anderson, J., Murray, L. & Peterson, B. S. (2017). Neural activity during very brief and clearly visible exposure to phobic stimuli. Human Brain Mapping. DOI: 10.1002/hbm.23533.

Siegel, P. & Gallagher, K. A.  (2015). Delaying in vivo exposure to a tarantula with very brief exposure to phobic stimuli. Journal of Behavior Therapy and Experimental Psychiatry, 46, 182-188.

Siegel, P. & Warren, R. (2013). Less is Still More: Maintenance of the Very Brief Exposure Effect One Year Later. Emotion, 13, 338-344.

Siegel, P., Han, E., Cohen, D., and Anderson, J. (2013).  A Detection-Identification Dissociation for Phobic Stimuli: Unconscious Perception? Cognition and Emotion, 27, 1153-1167.

Siegel, P., and Warren, R. (2013). The Effect of Very Brief Exposure on the Subjective Experience of Fear Induced by In Vivo Exposure. Cognition and Emotion, 27, 1013-1022.

Siegel, P. & Weinberger, J. (2012).  Less is More: The Effects of Very Brief Versus Clearly Visible Exposure on Spider Phobia. Emotion, 12, 394-402.

Siegel, P. & Peterson, B. (2012). Demonstrating Psychodynamic Conflict with a Neuropsychoanalytic Experimental Paradigm. Neuropsychoanalysis, 14, 219-228.

Siegel, P., Anderson, J. F. & Han, E. (2011). Very Brief Exposure II: The Effects of Unreportable Stimuli On Reducing Phobic Behavior.  Consciousness and Cognition, 20, 181-190.

Weinberger, J., Siegel, P., Seifert, C., & Duryall, J. (2011). What You Can’t See Can Help You. Consciousness and Cognition, 20, 173-180.

Siegel, P. & Demorest, A. (2010).  Affective Scripts: A Systematic Case Study of Change in Psychotherapy.  Psychotherapy Research, 20, 369-387.

Siegel, P. & Weinberger, J. (2009).  Very Brief Exposure: The Effects of Unreportable Stimuli on Fearful Behavior.  Consciousness and Cognition, 18, 939-951.