Quantifying the Unconscious
In this article, we make a straightforward yet significant argument: although the individual unconscious (in the psychoanalytic sense) cannot be directly studied through modern psychometrics, its degree of influence can be quantified through serotonin function and trait neuroticism. This provides an empirical bridge between classical psychoanalysis and contemporary neuroscience, demonstrating that an individual’s predisposition to live under the influence of their unconscious is largely genetic and significantly less shaped by childhood experiences than previously assumed.
Introduction
Modern psychology increasingly seeks to integrate classical psychoanalytic concepts of the unconscious with empirical science. A compelling hypothesis suggests that measurable traits and neurobiological markers—specifically, the personality trait of neuroticism and serotoninergic activity — may serve as proxies for the influence of what Carl Jung termed the “shadow” and Sigmund Freud called the “id” (1). These classical notions describe hidden, unconscious forces shaping emotions and behavior.
By examining neuroticism and serotonin levels, researchers can quantify the previously intangible effects of unconscious mechanisms. This article critically evaluates that hypothesis by drawing on scientific studies of neuroticism, serotonin, and emotional regulation. Crucially, it also asserts that directly confronting one’s most avoided thoughts and emotions is paramount for reducing the negative influence of the unconscious.
The Unconscious: From Shadow and Id to Modern Constructs
Both Jung’s shadow and Freud’s id refer to aspects of the unconscious mind that drive neurotic thoughts and behaviors if left unacknowledged (2). Jungian psychology conceptualizes the shadow as the repressed weaknesses, desires, and instincts that a person refuses to recognize as part of themselves (3). The id, in Freud’s framework, represents the primitive, instinctual component of the psyche, entirely unconscious and governed by the pleasure principle (4).
Historically, psychoanalysis linked unconscious forces to neurosis and emotional disturbances (5). Freud posited that repressed memories and emotions lead to neurotic symptoms, while Jung saw neurosis as a dissociation between the conscious mind and the unconscious shadow. Today, these ideas are reframed within the Big Five model as the trait neuroticism, a stable predictor of emotional instability, anxiety, and stress reactivity (6).
Modern neuroscience aligns with these ideas. The limbic system, particularly the amygdala, functions as a neural correlate for Freud’s id—regulating impulsive emotional responses (7). Moreover, reduced connectivity between the prefrontal cortex and amygdala in high-neuroticism individuals mirrors the psychoanalytic description of unconscious forces influencing behavior (8).
Neuroticism: A Trait Indicator of Unconscious Distress
Neuroticism is one of the Big Five personality dimensions, characterized by heightened emotional instability, anxiety, and stress sensitivity (9). Research suggests that neuroticism is significantly heritable (~40-60%) and influenced by serotoninergic function (10).
Individuals with high neuroticism exhibit:
Greater amygdala reactivity to perceived threats (11).
Increased risk for anxiety and depression (12).
Reduced serotonin transporter efficiency, leading to higher emotional reactivity (13).
These findings support the hypothesis that neuroticism is a quantifiable proxy for unresolved unconscious distress, aligning with Jung and Freud’s descriptions of an unintegrated psyche.
Serotonin: A Neurochemical Correlate of Negative Affect
Serotonin plays a crucial role in emotional regulation and impulse control. Individuals with high neuroticism exhibit reduced serotonin function, often due to genetic variations in the 5-HTTLPR gene (14).
Key evidence includes:
PET imaging studies reveal that higher neuroticism correlates with lower extracellular serotonin levels (15).
SSRIs reduce neuroticism over time, reinforcing serotonin’s role in emotional stability (16).
Psychedelic-assisted therapy, which enhances serotonin receptor activity, has been shown to lower neuroticism in long-term follow-ups (17).
This suggests that serotonin function serves as a neurobiological indicator of unconscious distress, reinforcing the idea that Jung’s shadow and Freud’s id may be partially explained by serotonin dysregulation.
Confronting the Shadow: Mitigating Unconscious Influences
Psychoanalytic traditions emphasize that integration of the unconscious leads to mental health improvements (18). Avoiding unresolved conflicts perpetuates neurosis, whereas confronting them fosters resilience (19).
Empirical research supports this view:
Exposure therapy (facing fears) reduces neuroticism over time (20).
Cognitive-behavioral therapy helps patients integrate avoided emotions, decreasing anxiety (21).
Mindfulness-based interventions that promote awareness of suppressed emotions have neuroplastic effects on serotonin systems (22).
By addressing repressed aspects of the psyche, individuals can recalibrate their neurobiological stress responses, reducing the physiological effects of an overactive unconscious.
Conclusion
By reframing Jung’s shadow and Freud’s id in terms of quantifiable constructs like neuroticism and serotonin, we create a scientific model for studying unconscious influences. This approach bridges classical psychoanalysis with modern neuroscience, offering empirical methods to assess the unconscious through personality traits and neurotransmitter function.
Although neuroticism and serotonin levels are imperfect proxies, they provide measurable insights into the effects of unconscious distress. The most effective strategy for mitigating this influence remains direct confrontation — whether through psychotherapy, self-reflection, or controlled exposure to one’s most avoided emotions.
Scientific evidence increasingly supports the notion that integrating the unconscious is not only a psychological necessity but also a neurobiological imperative. With advancements in personality neuroscience, we may soon develop even more refined methods to quantify and regulate unconscious processes, further modernizing Freud and Jung’s foundational insights.
Some of the References Used for the Article
Freud, S. (1923). The Ego and the Id. W. W. Norton & Company.
Jung, C. G. (1951). Aion: Researches into the Phenomenology of the Self. Princeton University Press.
Jung, C. G. (1959). The Archetypes and the Collective Unconscious. Princeton University Press.
Freud, S. (1900). The Interpretation of Dreams. Basic Books.
Eysenck, H. J. (1967). The Biological Basis of Personality. Charles C. Thomas.
Lahey, B. B. (2009). "Public health significance of neuroticism." American Psychologist, 64(4), 241-256.
DeYoung, C. G., et al. (2010). "Testing predictions from personality neuroscience." Journal of Personality and Social Psychology, 99(4), 716-733.
Servaas, M. N., et al. (2013). "Neuroticism and the brain: A quantitative meta-analysis." Neuroscience & Biobehavioral Reviews, 37(8), 1518-1529.
Costa, P. T., & McCrae, R. R. (1992). Four ways five factors are basic. Personality and Individual Differences, 13(6), 653-665.
Bouchard, T. J., & Loehlin, J. C. (2001). "Genes, evolution, and personality." Behavior Genetics, 31(3), 243-273.
Canli, T., et al. (2001). "Amygdala response to emotional stimuli." Science, 292(5517), 1671-1673.
Knutson, B., et al. (1998). "Serotonin, mood, and the brain." American Journal of Psychiatry, 155(3), 373-378.
MacLean, K. A., et al. (2011). "Psychedelic therapy and neuroticism reduction." Journal of Psychopharmacology, 25(11), 1453-1461.
Takano, A., et al. (2007). "Serotonin transporter binding in neurotic individuals." Biological Psychiatry, 62(6), 588-594.
Tang, S. Z., et al. (2009). "SSRI-induced neuroticism reduction." Archives of General Psychiatry, 66(12), 1323-1330.
