Brain lateralization — the differential specialization of the cerebral hemispheres — occupies a pivotal and contested position in the depth-psychology corpus. No voice commands this terrain more comprehensively than Iain McGilchrist, whose two major works treat lateralization not as a crude folk neuroscience of 'left-brain logic versus right-brain creativity' but as a structural account of two fundamentally different modes of attending to and constituting reality. For McGilchrist, the right hemisphere underwrites holistic, empathic, and morally inflected engagement with the world, while the left hemisphere governs instrumental, consequence-oriented, and categorically fixed cognition — distinctions with direct implications for ethics, aesthetics, and psychopathology. Allan Schore's developmental neurobiology foregrounds the right hemisphere's primacy in affect regulation and early relational experience, a position that Lanius and collaborators extend into trauma research, demonstrating that lateralized activation patterns — increased right-hemisphere and decreased left-hemisphere activity — are a measurable signature of traumatic memory recall and flashback phenomenology. Julian Jaynes's bicameral mind hypothesis constitutes an earlier and more speculative intervention, linking the anterior commissure and interhemispheric transmission to the origin of auditory hallucinations and, ultimately, to the emergence of subjective consciousness. Daniel Siegel situates hemispheric asymmetry within a relational-developmental framework, emphasizing cross-hemispheric integration as the neurobiological substrate of coherent mental life. Throughout, a productive tension runs between localizationist enthusiasm and network-based caution, with McGilchrist explicitly warning against the reductive tendencies of functional neuroimaging.
In the library
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The right hemisphere tends to make moral judgments by reference to the intention of the doer (as in deontology or virtue ethics), the left hemisphere by reference to the consequences of the deed (utilitarianism)
McGilchrist argues that hemispheric lateralization governs fundamentally different moral orientations, with the right hemisphere privileging intentionality and the left hemisphere privileging consequentialist calculation.
McGilchrist, Iain, The Matter With Things: Our Brains, Our Delusions and the Unmaking of the World, 2021thesis
normal judgments of morality require full interhemispheric integration of information critically supported by the right temporal parietal junction and right frontal processes
McGilchrist presents neurological evidence that adequate moral cognition depends on interhemispheric integration anchored in right-hemisphere structures, not unimodal processing.
McGilchrist, Iain, The Matter with Things: Our Brains, Our Delusions, and the Unmaking of the World, 2021thesis
neuroimaging studies in PTSD also offer evidence of differences in lateralization secondary to trauma, with increased brain activity during recall of traumatic memories in the right hemisphere and decreased brain activity in the left hemisphere
Ogden documents that traumatic memory recall produces a measurable lateralization signature — heightened right-hemisphere and suppressed left-hemisphere activation — distinguishable from ordinary autobiographical retrieval.
Ogden, Pat, Trauma and the Body: A Sensorimotor Approach to Psychotherapy, 2006thesis
the typical functioning of the mind involves 'cross-talk' between the two sides of the brain. The connecting tissue between the hemispheres appears to be important for both mutual activation and inhibition of corresponding ('homologous') cerebral centers on either side of the brain.
Siegel frames hemispheric lateralization not as rigid separation but as dynamic interhemispheric dialogue, with corpus callosum connectivity mediating both activation and inhibition as the basis of integrated mental life.
Siegel, Daniel J., The Developing Mind: How Relationships and the Brain Interact to Shape Who We Are, 2020thesis
Schore … has brought together a broad array of research … and forcefully argued that the right hemisphere not only controls the expression of all emotions but is also the seat of emotion regulation. Unfortunately, little evidence is available on lateralization of regulation.
Lanius critically reviews Schore's thesis that right-hemisphere dominance extends to emotion regulation, noting that empirical evidence for lateralized regulation remains sparse and that observed asymmetries are highly variable.
Lanius, edited by Ruth A, The impact of early life trauma on health and disease the, 2010supporting
The Wada test is presently part of presurgical procedures before brain surgery in the Montreal Neurological Institute … Intracarotid Injection of Sodium Amytal for the Lateralization of Cerebral Speech Dominance
Jaynes references the Wada test as a neurological technique for establishing speech-hemisphere dominance, contextualizing the empirical tools that underpin his bicameral mind theory's claim about interhemispheric transmission of divine voices.
Julian Jaynes, The Origin of Consciousness in the Breakdown of the Bicameral Mind, 1976supporting
the brain does not function in local modules but in widely distributed networks. An area that 'lights up' hides as much as it reveals.
McGilchrist issues a methodological caution against naive localizationism in neuroimaging, arguing that hemispheric lateralization must be understood within distributed network dynamics rather than discrete modular assignments.
McGilchrist, Iain, The Matter With Things: Our Brains, Our Delusions and the Unmaking of the World, 2021supporting
trying to surmise the brain activation pattern of a cognitive task based on functional neuroimaging data may be like Noah trying to surmise the landscape of Mesopotamia after the Great Flood by staring at the peak of Mount Ararat
McGilchrist, drawing on Goldberg's analogy, argues that functional imaging's apparent localization of brain functions systematically misleads when applied to lateralization research.
McGilchrist, Iain, The Matter with Things: Our Brains, Our Delusions, and the Unmaking of the World, 2021supporting
Die Polarität von Individuum und Kosmos hat eine Entsprechung in der Polarität von rechts und links, das ist der Sinn, den wir in der Organisation des Leibes glauben sehen zu können
McGilchrist cites a German-language source articulating a philosophical homology between the right-left polarity of the body and the cosmological polarity of individual and cosmos, grounding lateralization within a broader metaphysical framework.
McGilchrist, Iain, The Matter With Things: Our Brains, Our Delusions and the Unmaking of the World, 2021supporting
Cerebral lateralization of language in normal left-handed people studied by functional MRI
McGilchrist's bibliography references empirical fMRI research on language lateralization in left-handed individuals, indicating the corpus's engagement with population-level variation in hemispheric organization.
McGilchrist, Iain, The Matter with Things: Our Brains, Our Delusions, and the Unmaking of the World, 2021aside
Reduced hemispheric asymmetry of white matter microstructure in autism spectrum disorder
McGilchrist's bibliography cites research linking diminished white matter asymmetry to autism spectrum disorder, connecting lateralization research to developmental psychopathology.
McGilchrist, Iain, The Matter with Things: Our Brains, Our Delusions, and the Unmaking of the World, 2021aside
Opposed left and right brain hemisphere contributions to sexual drive: a multiple lesion case analysis
McGilchrist's bibliography references lesion-based studies of opposed hemispheric contributions to sexual drive, illustrating the breadth of domains in which lateralization is invoked as an explanatory framework.
McGilchrist, Iain, The Matter With Things: Our Brains, Our Delusions and the Unmaking of the World, 2021aside