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Behavior directed toward harming another who is motivated to avoid that harm. Anger, emotional arousal, aggressive thoughts and scores on experimental tasks should not automatically be equated with enacted harm. Measurement must specify which component is observed.

The degree of activation associated with an emotional state. Emotional arousal is distinct from emotional valence: both positive and negative states can be highly activating.

Naturalistic facial evidence supports biological and social regularities, but gives limited support to a universal one-to-one code for basic emotions. The relevant contrast is between describing a facial movement and inferring its cause. The same visible action can accompany an emotional episode, communicate affiliation or serve a task. A strong basic emotion theory needs independent evidence linking a category of felt emotion to a characteristic pattern across situations, rather than defining the category by the pattern it is supposed to explain.

Posed photographs are useful controlled stimuli, but agreement about them answers a different question from why people move their faces in ordinary life. Forced-choice emotion recognition supplies observers with labels and alternatives; it can encourage consensus even when spontaneous descriptions would differ. Recognition of a prototype also does not establish that its full configuration occurs frequently in lived episodes. Naturalistic studies should therefore code movements independently of a category judgment, record the social setting, and obtain an independent indicator of experience where possible. The Facial Action Coding System helps separate visible actions from their interpretation; anatomical coding is not itself a measurement of feeling.

Robert E. Kraut and colleagues' 1979 observations make the methodological issue concrete. At a bowling alley, bowlers were especially likely to smile while socially engaged, including when facing companions, rather than simply after a successful delivery. Observations in other settings also implicated social engagement. Bowling supplies identifiable outcome events and changes of orientation towards an audience, so it offers a useful setting for separating success from immediate social contact. However, a good score is an imperfect indicator of what that individual feels at that instant; the study cannot infer the absence of happiness merely from a lack of smiles.^[ref]

María-Ángeles Ruiz-Belda and colleagues addressed this limitation in 2003 by adding reports of feeling in field studies of bowlers and soccer fans. Among those reporting happiness, smiling was much more probable during social interaction than outside it. The key contribution is the separation of reported happiness from the presence of a smile, not merely the observation that social people smile. Reports still have timing and reconstruction limitations, and social interaction can itself alter felt intensity. Nevertheless, these observations are difficult to reconcile with the simple claim that happiness reliably releases a smile regardless of audience.^[ref]

The evidence does not require treating biological expression and communication as mutually exclusive. An inherited movement repertoire could become selectively deployed towards partners. Conversely, describing a smile as communicative does not show that its producer lacks happiness. A display rule may suppress or amplify a response. But if every absent expression is retrospectively called suppression and every unexpected expression is called a disguise, the claim loses predictive content. A useful version must specify the circumstances of suppression independently and predict differences before seeing the faces.

Evidence from blindness strengthens the case for a biological contribution without settling the strong universality claim. David Matsumoto and colleagues compared spontaneous expressions of congenitally blind, noncongenitally blind and sighted athletes. Similarities show that visual imitation is not necessary for all features of the observed repertoire. They do not remove social experience, other sensory learning, shared anatomy or competition-related goals. Nor do they establish a unique correspondence between each movement and a consciously felt category.^[ref]

A complementary result concerns interpretation rather than natural production. Rachael E. Jack and colleagues used generated dynamic faces and reverse correlation to estimate observers' category representations. Cultural differences in those representations challenge a single universal observer code. This is not direct evidence that the same cultural groups make different spontaneous movements in every emotional situation. Production and interpretation require separate tests.^[ref]

A decisive programme would sample episodes rather than only successful examples, include nonsocial and social periods within the same people, and obtain time-linked reports without prompting a fixed inventory of categories. Facial coders should be blind to reports and outcomes; analyses should distinguish within-person effects from differences between people. Researchers should test the entire distribution: how often a movement occurs without the proposed feeling, and how often the feeling occurs without the movement. A distinctive expression might still be informative without being necessary or sufficient. To establish a specifically basic category, the pattern must also outperform alternatives based on emotional valence, emotional arousal, action and social intention.

Empathy combines partly shared affective mechanisms with computations that represent another person's state; regional overlap does not show that the underlying neural code is identical. The answer depends on what empathy means. Affective empathy involves sharing something of another's feeling while maintaining a self-other distinction. Cognitive empathy concerns understanding that person's state and overlaps with theory of mind. Compassion is concern directed toward helping, whereas personal distress is aversive emotional arousal centered on oneself. These components can vary independently, so a single neural contrast cannot settle all of them.

A shared-processing hypothesis predicts that some mechanisms supporting one's own affect also contribute when another person suffers. Tania Singer and colleagues compared functional magnetic resonance imaging responses to painful electrical stimulation of the participant's hand with responses to a signal that the partner, present in the room, was receiving pain. Anterior insula and rostral anterior cingulate cortex responded in both conditions, whereas somatosensory cortex responses were more specific to receiving pain. The cue-based partner condition helped separate affective response from simply seeing an injured body part.^[ref]

The result supports partial overlap at the measured regional scale, not duplication of the whole first-person experience. Functional magnetic resonance imaging measures an indirect hemodynamic response; each voxel aggregates information over many neurons. A region can contain intermingled populations, and different computations can increase its average response. Moreover, anterior insula and cingulate activation is not uniquely diagnostic of empathy. Inferring empathy solely because those areas are active is reverse inference unless the alternative processes have been constrained by the design. Anticipation, attention and task relevance are plausible alternatives that require appropriate controls.

Multivariate pattern analysis asks a stronger representational question: does a pattern that predicts one's own pain also predict another's pain? Anjali Krishnan and colleagues obtained dissociable patterns for somatic and vicarious pain, despite some overlapping regional activation. Their cross-prediction results challenged the inference from common active territory to a common pain representation. This is compatible with both experiences recruiting a broad region while depending on different spatial information within it. It does not establish that no shared component exists at any scale.^[ref]

The logical distinction can be made without empirical assumptions. Two four-location responses, $(3,1,3,1)$ and $(3,3,1,1)$, each have mean two and positive activation everywhere. Their mean-centered patterns are $(1,-1,1,-1)$ and $(1,1,-1,-1)$, whose dot product is zero. Thus identical regional means can conceal different codes. Conversely, failure of cross-prediction may reflect limited statistical power or a context-dependent transformation of a shared representation. Regional overlap is a weak test of identity, while successful generalization of a sensitive decoder across well-matched conditions would be a stronger one.

Intervention adds a complementary test. Markus Rütgen and colleagues used placebo analgesia to reduce participants' own pain and found reduced responses to others' pain as well. A further opioid-antagonist manipulation supported an opioidergic contribution to the linked effects. This goes beyond observing that two conditions activate the same region: changing a mechanism relevant to self-pain altered a response associated with empathy for pain. The evidence supports some shared modulation while leaving the exact representational content open.^[ref]

There are still alternatives to a literal shared-pain code. Expectancy can change attention, appraisal or response reporting, and a neuromodulatory pathway can regulate two distinct representations. Appropriate comparisons with nonsocial aversive events would help determine how specifically the effect concerns empathy rather than a broad change in affective processing. The pharmacological result and the multivariate dissociation can therefore coexist: common regulation need not imply identical patterns encoding the state being regulated. Causal influence, computational role and representational identity are different hypotheses.

Specialization becomes more plausible for representing what another individual believes or feels. Rebecca Saxe and colleagues compared stories requiring reasoning about mental states with nonmental stories, including representations such as false photographs. Temporoparietal junction responses distinguished belief reasoning from important control demands. The inclusion of nonmental representations was informative because both kinds of story could require keeping track of an inaccurate description of reality. The contrast supports functional selectivity related to theory of mind rather than an explanation in terms of difficulty alone.^[ref]

This is evidence for a socially selective computation under the tested contrasts, not proof that an entire anatomical area operates only during social interaction. Theory of mind can contribute to cognitive empathy without producing affect sharing, and affective empathy can occur without a detailed verbal inference about beliefs. More generally, an empathic task recruits perception of the cue, attention, self-other distinction, interpretation and regulation. Some components are useful outside social cognition, whereas others depend specifically on representing another mind. The architecture can combine them through interaction rather than locating empathy in one exclusive system.

Converging tests should separate these hypotheses. Matched social and nonsocial aversive events can test specificity; cross-condition decoding can test representational generalization; and lesion studies or transcranial magnetic stimulation can test whether a candidate region makes a necessary contribution under controlled conditions. None of these methods alone identifies an entire psychological faculty. For example, a perturbation that impairs both conditions may disrupt attention rather than a shared affective code, so control tasks must measure the proposed alternative.

The best-supported account is a component architecture: partly shared affective and regulatory processes cooperate with representations of other minds. Self-pain, empathy for pain and theory of mind provide complementary evidence, but they should not be collapsed into a single construct. Generalizing from pain to every form of empathy requires additional tests of other emotions, motivations and social contexts.