Santiesteban, I., Banissy, M., Catmur, C., & Bird, G. (2012) | References

Core Concept

The Right Temporoparietal Junction as a Hub for Social Cognition

The right temporoparietal junction (rTPJ) occupies a unique position in the social brain—both anatomically, where the temporal and parietal lobes meet, and functionally, as a hub that integrates information essential for understanding other minds. This study by Santiesteban and colleagues provides causal evidence that the rTPJ supports two seemingly distinct but fundamentally interrelated capacities: the ability to take another person's perspective and the ability to distinguish one's own mental states from those of others.

Prior neuroimaging research had established correlational links between rTPJ activity and social cognitive tasks, but this study went further by using transcranial direct current stimulation (tDCS) to modulate rTPJ activity and measure the resulting changes in social cognitive performance. Anodal stimulation, which increases neural excitability, enhanced both perspective-taking and self-other distinction. This dual enhancement reveals that these capacities are not independent or opposing but share neural infrastructure. The rTPJ enables you to simulate another's viewpoint while maintaining the computational distinction that this simulated perspective belongs to them, not you.

Transcranial Direct Current Stimulation: A Window into Causation

The methodological innovation of this study lies in its use of tDCS to establish causation rather than mere correlation. While fMRI studies can show that the rTPJ activates during social cognitive tasks, they cannot demonstrate that rTPJ activity is necessary for those tasks—activation might be epiphenomenal. tDCS allows researchers to modulate neural activity and observe resulting behavioural changes, providing evidence that the rTPJ causally contributes to social cognition.

The study employed a between-subjects design where participants received either anodal (excitatory), cathodal (inhibitory), or sham (placebo) stimulation over the rTPJ before completing perspective-taking and self-other distinction tasks. Anodal stimulation improved performance on both tasks; cathodal stimulation showed trends toward impairment. This bidirectional pattern strengthens the causal interpretation: if simply participating in the experiment improved performance, both active stimulation conditions should show enhancement, but instead only excitatory stimulation helped while inhibitory stimulation trended toward harm.

The findings complement lesion studies showing that damage to the rTPJ impairs theory of mind and perspective-taking. Together, these lines of evidence establish the rTPJ as causally necessary for healthy social cognition—and identify it as a potential locus of dysfunction in conditions characterised by social cognitive deficits.

Self-Other Distinction: The Foundation of Healthy Social Cognition

One of the study's most significant contributions is demonstrating that self-other distinction is not opposed to perspective-taking but foundational to it. To accurately understand another's viewpoint, you must first recognise that their viewpoint exists as separate from your own. Without this distinction, you cannot truly take another's perspective—you can only project your own perspective onto them and assume they share it.

This insight has profound implications for understanding narcissistic personality disorder. The narcissist's inability to take others' perspectives is not simply a motivational failure (they don't care enough to try) but a computational failure rooted in impaired self-other distinction. When the boundary between self and other is unclear, the narcissist literally cannot represent the other's perspective as distinct from their own. They assume others think what they think, feel what they feel, want what they want—and when reality contradicts this assumption, they experience confusion, rage, or disbelief rather than recognition of the other's separateness.

The rTPJ's role in maintaining self-other distinction while enabling perspective-taking explains why healthy social cognition requires both capacities working together. You must be able to simulate another's experience without losing track of whose experience you're simulating. The rTPJ provides this tracking function, enabling empathic attunement without loss of self.

Implications for Understanding Empathy Deficits

Empathy is not a single capacity but a constellation of processes: cognitive empathy (understanding what others think and feel), affective empathy (sharing others' emotional states), and compassionate response (being moved to help). The rTPJ primarily supports cognitive empathy—the perspective-taking component. This research demonstrates that enhancing rTPJ function enhances cognitive empathy, providing a neural target for understanding and potentially addressing empathy deficits.

In narcissism, cognitive empathy deficits are central to the disorder's interpersonal pathology. The narcissist may experience emotional contagion (feeling distressed when exposed to others' distress) but cannot accurately represent what the other person is experiencing. They interpret others' emotions through their own lens: if you're upset, it must be about them; if you're happy, you must be happy for reasons related to them. This egocentric interpretation is not laziness or indifference—it reflects a genuine inability to construct accurate representations of others' mental states as distinct from their own.

This study suggests that the cognitive empathy component of narcissistic deficit has a specific neural substrate that, at least in healthy individuals, can be enhanced through stimulation. Whether similar enhancement might benefit individuals with personality disorders remains an open question, but the research establishes that the relevant circuitry is modifiable rather than fixed.

Original Context

The Turn Toward Causal Methods in Social Neuroscience

This study appeared during a methodological turning point in social neuroscience. The first decade of the twenty-first century had produced extensive fMRI research identifying brain regions activated during social cognitive tasks. The rTPJ had been implicated in numerous studies of theory of mind, moral judgment, and perspective-taking. However, activation during a task does not prove that the region is necessary for the task—it might reflect secondary processing, attentional demands, or other epiphenomenal activity.

The use of non-invasive brain stimulation techniques like tDCS and transcranial magnetic stimulation (TMS) allowed researchers to move from correlation to causation. By modulating activity in specific regions and observing behavioural consequences, these methods could test whether regions identified through fMRI were truly necessary for the functions attributed to them. This study was among the first to demonstrate that enhancing rTPJ activity actually improved social cognitive performance—not just that the rTPJ activated during such tasks.

Integration with Theory of Mind Research

The study built on decades of research into theory of mind—the capacity to attribute mental states to oneself and others and to understand that others have beliefs, desires, and intentions that may differ from one's own. Theory of mind had been studied extensively in developmental psychology (children develop it around age four), autism research (where theory of mind deficits are implicated), and philosophy of mind (which examines the nature of mental state attribution).

Neuroimaging research had converged on a network of brain regions supporting theory of mind, with the rTPJ consistently identified as a key node. This study added crucial evidence by showing that the rTPJ's role was not merely correlational but causal. The finding that enhancing rTPJ activity improved perspective-taking validated the theoretical importance assigned to this region and suggested it as a target for understanding and potentially treating conditions characterised by theory of mind deficits.

Self-Other Representation in Cognitive Science

The study also connected to broader research on how the brain represents self and other. Cognitive science had established that understanding others involves simulation—using one's own mental machinery to model others' experiences. But simulation creates a problem: how do you distinguish a simulated experience (representing what another feels) from a direct experience (what you yourself feel)? Without this distinction, simulation would lead to confusion between self and other.

The rTPJ had been proposed as a key region for maintaining this distinction, and this study provided causal evidence for that proposal. By showing that enhanced rTPJ function improved both perspective-taking AND self-other distinction, the research demonstrated that these capacities are not in tension but synergistic. The rTPJ supports simulation-based understanding of others while simultaneously maintaining the computational boundaries that prevent confusion between simulated and direct experience.

Clinical Applications on the Horizon

At the time of publication, researchers were beginning to explore whether brain stimulation techniques could have clinical applications for social cognitive deficits. Studies had examined tDCS and TMS effects on various cognitive functions, with some showing promise for conditions like depression. This study opened the possibility that social cognition itself might be a target for stimulation-based intervention.

While translating these findings to clinical populations would require extensive additional research, the study established a crucial proof of concept: social cognitive abilities are not fixed traits but modifiable capacities that can be enhanced through neural intervention. This opened theoretical space for imagining treatments that might address the social cognitive deficits characteristic of personality disorders, autism spectrum conditions, or acquired brain injuries affecting the rTPJ.

For Survivors

Understanding Why the Narcissist Could Not See You

If you were raised by or partnered with a narcissist, you know the bewildering experience of trying to communicate your perspective to someone who seemed constitutionally incapable of grasping it. You explained how their behaviour affected you; they responded as if you'd said nothing, or twisted your words, or accused you of attacking them. This research helps explain why: the narcissist may genuinely lack the neural infrastructure for taking perspectives other than their own.

The rTPJ dysfunction that characterises narcissistic personality disorder means the narcissist cannot easily compute that you have a different viewpoint—a different experience of the same events, different feelings about their behaviour, different needs that matter independently of their own. When you tried to share your perspective, they literally could not represent it as distinct from their own. If you felt hurt, they either couldn't process this information or interpreted it through their own lens: you were attacking them, you were too sensitive, you were making things up.

Understanding this as a neurobiological deficit—not merely a choice to be selfish—can help explain why nothing you said ever seemed to register. You weren't failing to communicate clearly enough. They weren't capable of receiving the communication you were sending.

The Confusion of Boundaries You Experienced Has Neural Correlates

Narcissists characteristically blur boundaries between self and other, treating you as an extension of themselves rather than a separate person. They assume you share their opinions, should anticipate their needs, and exist to fulfil their purposes. When you assert your separateness, they react with rage, confusion, or injury—as if you've amputated part of them.

This research illuminates the neural basis of this boundary confusion. The rTPJ supports self-other distinction—the computational capacity to represent that your mental states are yours and others' mental states are theirs. When this capacity is impaired, the narcissist genuinely cannot maintain the distinction. They merge with you, project their experiences onto you, and experience your separateness as abandonment or attack.

This understanding can help you recognise that the boundary violations you experienced were not about you—not about your insufficient boundaries, your failure to resist, or your unclear communication. They reflected the narcissist's fundamental incapacity to perceive you as a separate person with your own valid experience.

Rebuilding Your Own Self-Other Distinction

After prolonged exposure to narcissistic abuse, you may have internalised the confusion. Chronic gaslighting and projection may have eroded your ability to know what you feel versus what you were told you feel, what you think versus what you were told to think, where you end and others begin. Recovery involves rebuilding these distinctions that the narcissist systematically attacked.

This research offers hope by demonstrating that perspective-taking and self-other distinction are not fixed traits but modifiable capacities supported by neural circuits that can be strengthened. The same brain region that enables you to understand others' perspectives also enables you to know which experiences are yours. Strengthening one strengthens the other. You can rebuild your capacity to connect with others (perspective-taking) while simultaneously rebuilding your sense of separate selfhood (self-other distinction).

Recovery practices that help you identify your own feelings, validate your own perceptions, and maintain boundaries are not merely psychological exercises—they are supporting neural circuits that were disrupted by the abuse.

The Integration of Connection and Autonomy

Survivors often feel caught between connection and autonomy, as if caring about others and having a clear sense of self are in tension. The narcissist may have reinforced this false dichotomy: if you tried to be close, you lost yourself; if you protected yourself, you were accused of not caring. This research suggests the dichotomy is false.

Healthy social cognition involves both perspective-taking (connection) and self-other distinction (autonomy), supported by the same neural infrastructure. You do not have to choose between understanding others and knowing yourself. The rTPJ supports both simultaneously. Recovery involves developing both capacities together—learning to empathize without losing yourself, to connect without merging, to care without becoming enmeshed.

The narcissist may have made connection feel dangerous because connection with them required losing yourself. But connection with healthier people works differently. In relationships where both parties have functioning perspective-taking AND self-other distinction, you can be close while remaining yourself. The neural infrastructure for this already exists in you; recovery involves rebuilding access to it.

For Clinicians

Assessing Perspective-Taking and Self-Other Distinction in Survivors

Survivors of narcissistic abuse often present with disruptions in both perspective-taking and self-other distinction—the very capacities this research identifies as rTPJ-dependent. Clinicians should assess these capacities specifically rather than subsuming them under general relationship difficulties or trauma symptoms.

Assessment questions might include: Do you often doubt your own perceptions of interpersonal situations? Do you find it hard to know what you feel versus what others want you to feel? Do you struggle to imagine that others might think or feel differently than you expect? Do you lose your sense of self in close relationships? Do you merge with others' emotions and have difficulty separating?

Survivors may show patterns in either direction: some have impaired perspective-taking (they assume others think as they do, having learned this from a narcissist who demanded such assumptions); others have impaired self-other distinction (chronic boundary violations eroded their sense of separate selfhood). Many show both. Understanding these as related deficits—both supported by the rTPJ and its connected circuits—can inform treatment planning.

The rTPJ in Case Conceptualisation of Narcissistic Patients

For clinicians treating individuals with narcissistic features or full narcissistic personality disorder, this research provides a neural framework for understanding core deficits. The narcissist's inability to take perspectives and tendency to blur self-other boundaries are not merely characterological but have neural substrates. This framing neither excuses the behaviour nor suggests it is completely fixed, but contextualises why change is difficult.

In therapy, the narcissistic patient's difficulty imagining the therapist's perspective or recognising that the therapist exists as a separate person with their own experience becomes understandable as rTPJ dysfunction. The tendency to project onto the therapist, to assume the therapist shares their views, and to react with narcissistic injury when the therapist demonstrates separateness all reflect impaired self-other distinction.

Treatment approaches that explicitly work on perspective-taking and self-other distinction—having the patient imagine others' viewpoints, repeatedly demonstrating that others have separate valid experiences, practicing the recognition that others' feelings are not about the patient—may be addressing the specific neural circuits that are impaired.

Mentalization-Based Approaches and the rTPJ

Mentalization-based treatment (MBT), developed by Fonagy and Bateman, focuses on developing the capacity to understand behaviour in terms of underlying mental states—both one's own and others'. This study provides neural grounding for mentalization interventions: the rTPJ is a key node supporting the perspective-taking and self-other distinction that mentalization requires.

Clinicians using MBT or mentalization-informed approaches can understand their work as supporting rTPJ function and its connections. When you ask "What do you think they were feeling?" you are inviting perspective-taking. When you observe "That's how you felt about it, but they might have felt differently," you are supporting self-other distinction. When you model curiosity about mental states while maintaining boundaries, you are demonstrating integrated rTPJ function.

The research also suggests why mentalizing both self and other improve together rather than trading off—they share neural infrastructure. Helping patients understand their own mental states (self-mentalization) and others' mental states (other-mentalization) are complementary rather than competing therapeutic goals.

Implications for Trauma Therapy with Survivors

When treating survivors of narcissistic abuse, this research suggests that explicitly working on perspective-taking and self-other distinction may address neural circuits affected by the abuse. Survivors whose sense of self was systematically undermined need help rebuilding self-other distinction. Those who learned to doubt their perceptions of others need help rebuilding accurate perspective-taking.

Interventions might include: explicitly validating the survivor's perspective as distinct and valid; practicing taking others' perspectives in low-stakes scenarios; working on boundary-setting as a behavioral expression of self-other distinction; helping survivors recognize projection (their own and others') as a failure of self-other distinction; and building tolerance for the reality that others have different, valid experiences.

The therapist's own perspective-taking and self-other distinction model healthy function. When you accurately perceive the patient's experience while maintaining your own perspective, you are demonstrating what healthy social cognition looks like and providing the patient with a template for developing it themselves.

Broader Implications

Understanding the Narcissist's Social World

This research illuminates why narcissists create the particular interpersonal environments they do. Without intact self-other distinction, the narcissist cannot experience others as truly separate. Family members become extensions; employees become props; partners become mirrors. When others assert separateness—their own opinions, needs, boundaries—the narcissist experiences this as fragmentation or betrayal rather than normal human differentiation.

The narcissist's social world is thus fundamentally different from that of neurotypical individuals. They are not navigating relationships between separate people but managing a field of self-extensions that keep threatening to become separate. The rage at boundaries, the confusion at others' needs, the demand for mirroring—these emerge from a brain that cannot easily compute other minds as truly other.

This understanding helps explain why reasoning with narcissists often fails: you are attempting to communicate across a fundamental difference in how social reality is represented. The conversation you think you're having—between two separate minds with different perspectives—is not the conversation the narcissist is having, in which separate perspectives don't fully exist.

Developmental Origins of rTPJ Dysfunction

The rTPJ develops throughout childhood and adolescence, with its function shaped by interpersonal experience. Children learn to distinguish self from other through countless interactions in which caregivers treat them as separate minds with valid perspectives. When a narcissistic parent treats the child as an extension of themselves—projecting onto them, failing to see their perspective, violating their boundaries—the child may not develop normal self-other distinction.

This creates a potential intergenerational mechanism: the narcissistic parent's rTPJ dysfunction leads to parenting that impairs the child's social brain development, producing the next generation of perspective-taking and self-other distinction deficits. The cycle can be interrupted by other relationships that provide what the narcissistic parent could not—experiences of being seen as a separate person whose perspective matters.

Educational and clinical interventions during childhood sensitive periods might support healthy rTPJ development in at-risk children. Teaching theory of mind explicitly, providing mentoring relationships with adults who model perspective-taking, and creating environments where children's perspectives are valued might buffer the effects of narcissistic parenting on social brain development.

The Neuroscience of Moral Judgment

The rTPJ has been implicated not only in perspective-taking but in moral judgment—determining whether harmful actions were intentional or accidental, whether agents deserve blame or excuse. This connection makes sense: judging moral responsibility requires taking the agent's perspective to understand their intentions and knowledge. Without this perspective-taking, moral judgments become crude, focusing only on outcomes rather than mental states.

This may explain aspects of the narcissist's moral reasoning. The narcissist who cannot take perspectives may have difficulty with mature moral judgment that considers others' intentions and circumstances. Their morality may be childlike—focused on whether outcomes affected them positively or negatively rather than on the mental states of moral agents. This is not moral indifference but a specific limitation in the neural infrastructure supporting nuanced moral cognition.

Implications for Psychopathy and Antisocial Personality

While this research focuses on healthy participants, its implications extend to understanding the neural basis of social cognitive deficits across personality pathology. Psychopathy and antisocial personality disorder also involve perspective-taking deficits, though the profile differs from narcissism. Research comparing rTPJ function across personality disorders might reveal distinct patterns—perhaps explaining why narcissists seem oblivious to others' perspectives while psychopaths can model others' minds for manipulation.

The finding that rTPJ stimulation enhanced social cognition in healthy participants raises questions about whether similar interventions might benefit individuals with personality disorders. Significant obstacles exist—most notably that such individuals rarely seek treatment voluntarily—but the research establishes that relevant neural circuits are modifiable in principle.

Mirror Neurons and the Self-Other Problem

This research connects to the broader question of how mirror neurons—which fire both when performing actions and when observing others perform them—contribute to social cognition without creating self-other confusion. If the same neurons fire whether you do something or watch someone else do it, how do you know which experience is yours?

The rTPJ appears to provide part of the answer: it maintains the computational distinction that prevents simulation from becoming confusion. Mirror neuron activity enables understanding through simulation; rTPJ activity ensures you know the simulated experience belongs to the other, not yourself. Dysfunction in either system could impair social cognition, but in different ways—mirror neuron dysfunction might impair understanding, while rTPJ dysfunction might impair the self-other distinction that makes understanding useful.

Future Directions: Enhancement, Treatment, and Ethics

This study opens questions about whether and how social cognitive enhancement might be pursued. Could tDCS or other brain stimulation techniques enhance empathy in healthcare providers, negotiators, or leaders? Could they treat social cognitive deficits in personality disorders, autism spectrum conditions, or acquired brain injuries? What ethical considerations govern enhancement of capacities as central to personhood as understanding other minds?

The research suggests that social cognition is malleable—neither fixed at birth nor immutable after development. This malleability creates both opportunity (deficits might be addressed) and concern (capacities might be manipulated). As brain stimulation technology advances, society will need frameworks for deciding when enhancement is appropriate and who should have access to it.

FAQs

Is the rTPJ the only brain region involved in perspective-taking and empathy?

No—the rTPJ works within a broader network of regions supporting social cognition. The medial prefrontal cortex is involved in thinking about mental states; the anterior insula contributes to emotional awareness and empathy; the superior temporal sulcus processes social signals like gaze and biological motion; the mirror neuron system supports understanding through simulation. The rTPJ's special contribution is maintaining self-other distinction while processing social information. Dysfunction in any node of this network could impair social cognition, but the rTPJ's role in distinguishing self from other is particularly relevant to narcissistic pathology.

How long do the effects of brain stimulation last?

In this study, participants received a single session of tDCS, and effects were measured immediately afterward. Such effects are typically temporary—lasting minutes to hours—rather than producing lasting change. Multiple sessions over time might produce more durable effects through neuroplastic mechanisms, but this remains to be demonstrated. The study's importance lies in establishing that the rTPJ causally supports perspective-taking and self-other distinction, not in demonstrating a treatment protocol.

Could stimulating my own rTPJ help me recover from narcissistic abuse?

This is not recommended. tDCS devices are available commercially, but self-administered brain stimulation carries risks and the protocols used in research are carefully calibrated. More importantly, the study enhanced perspective-taking in healthy participants—it did not address whether similar enhancement would help trauma survivors, whose needs are different. Recovery from narcissistic abuse is better supported through therapy, safe relationships, and practices that rebuild trust in your own perceptions. The research's value for survivors is in understanding the narcissist's deficits, not in pursuing self-enhancement.

Do narcissists know they lack perspective-taking ability?

Generally, no. Lacking the capacity to perceive others' perspectives includes lacking the capacity to perceive that you lack this capacity. The narcissist does not experience themselves as unable to take perspectives—they experience others as incomprehensible, unreasonable, or adversarial. When feedback suggests they've failed to understand someone's viewpoint, they typically attribute the problem to the other person (who is being unclear, manipulative, or overly sensitive) rather than to their own deficit. This lack of insight is part of why narcissism is so treatment-resistant.

How does this relate to object constancy?

Object constancy—the capacity to maintain a stable representation of others even when they're absent or when your feelings toward them fluctuate—is related to but distinct from self-other distinction. Object constancy develops earlier and involves maintaining representations of others across time and emotional states. Self-other distinction involves the ongoing capacity to recognize that others' mental states are theirs, not yours. Narcissists may have deficits in both: they struggle to maintain stable representations of others (splitting between idealization and devaluation) and struggle to distinguish others' perspectives from their own. Both deficits contribute to the chaotic interpersonal world the narcissist creates.

If perspective-taking can be enhanced, why don't narcissists just develop it naturally over time?

Several factors prevent natural improvement. First, the narcissist's defensive structure protects them from the feedback that might promote growth—they externalize problems rather than recognizing their own deficits. Second, neuroplasticity decreases with age, making adult change harder than childhood development. Third, perspective-taking requires practice, but the narcissist avoids the experiences that would provide practice—they don't genuinely engage with others' viewpoints because doing so threatens their defensive grandiosity. Fourth, the narcissist's environment often becomes increasingly curated to confirm their views, reducing exposure to perspectives that might promote growth. Change requires both the capacity to change and the experiences that promote change; narcissists typically lack sufficient access to both.

How might this research inform couples therapy involving a narcissistic partner?

Therapists should recognize that the narcissistic partner may genuinely lack the capacity for the perspective-taking that couples therapy typically requires. Standard interventions asking partners to understand each other's viewpoints may be ineffective if one partner cannot perform this cognitive operation. Therapy might need to focus more on explicit teaching of perspective-taking (rather than assuming the capacity), on behavior change rather than insight, and on helping the non-narcissistic partner develop realistic expectations. The research also suggests why couples therapy often fails when one partner is narcissistic—the fundamental asymmetry in social cognitive capacity makes the mutual perspective-taking that couples therapy requires neurologically unavailable to one partner.

Could this research explain why narcissists seem to lack genuine remorse?

Yes. Genuine remorse requires taking the perspective of the person you've harmed—understanding their experience, their pain, their injury. Without this perspective-taking capacity, what might appear as remorse in a narcissist is typically either self-focused (distress at consequences to themselves, damage to their image) or performative (learned behaviors that deflect criticism without underlying perspective-taking). The research helps explain why narcissists may sometimes say sorry but the apology feels hollow—they cannot fully compute the experience of the person they're apologizing to, so the apology lacks the perspective-taking that gives remorse its meaning and its power to repair relationships.

Enhancing social ability by stimulating right temporoparietal junction

APA Citation