Interpersonal Behavior

Triandis argues that interpersonal behavior can be explained by a single general theoretical model rather than by a collection of domain-specific mini-theories. The book rejects the fragmented state of social psychology, where helping behavior, aggression, conformity, and attraction each generated separate explanatory frameworks with little integration. Triandis proposes that behavior is determined by behavioral intentions, which are themselves shaped by perceived consequences, social norms, and affective responses, with habit and facilitating conditions moderating the intention-behavior link. He then applies this model consistently across the book's substantive chapters, demonstrating that the same underlying variables can account for phenomena that had been treated as theoretically unrelated. The ambition is integrative: one framework, many domains.

The Triandis model of interpersonal behavior posits that behavior is a function of behavioral intentions, habit, and facilitating conditions. Intentions are shaped by perceived consequences (an expectancy-value calculation), social norms (what others expect), and affect (emotional responses to the behavior). Triandis deliberately made the model complex and difficult to operationalize as a single index, believing that the variables, while superficially similar to Fishbein's, were conceptually distinct . Later comparisons with Fishbein's theory of reasoned action reported that Triandis's model produced larger explained variances, though the comparisons were compromised by using the same items to measure variables from both theories—an approach Triandis himself labeled invalid . The model's inclusion of habit and facilitating conditions anticipated later extensions of the theory of planned behavior.

Arthur G. Miller, reviewing in Contemporary Psychology in 1977, called it 'an inspired and welcome treatment' and an important occasion in social psychology . Miller identified Triandis's two major goals as summarizing the literature on interpersonal behavior and presenting a theoretical framework useful for studying it. The review noted that Triandis conceives of interpersonal behavior in the broadest possible sense—from nonverbal to verbal, from fantasies to concrete acts—and even argues that doing nothing can sometimes count as behavior . Miller praised Triandis's competence and the book's scope, observing that Triandis applies his conceptual model to helping, aggression, conformity, social intimacy, perception, attribution, and attraction. The review's tone was respectful rather than uncritical, but it treated the book as a significant synthetic achievement.

Culture appears most explicitly in Chapter 7, 'The Antecedents of Action,' which includes a section on 'Culture and Behavior,' and in Chapter 9, 'Some Practical Implications,' which opens with 'Interaction across Cultures' . Triandis does not yet treat culture as a dimensional variable in the manner of his later individualism-collectivism work; instead, culture functions as a context that shapes the antecedents in his model—perceived consequences, norms, and affect. The book's practical chapter extends this to employment interviews, supervisor-subordinate relations, teacher-pupil relations, and marital relations . This placement of culture within a general behavioral model, rather than as a separate specialty, prefigures Triandis's later insistence that culture must be integrated into psychological theory rather than appended to it.

The book extends the cognitive orientation of Attitude and Attitude Change (1971) into a broader behavioral model. Where the earlier book treated attitudes as cognitive-affective-behavioral composites, Interpersonal Behavior asks how those composites, together with norms, affect, and habit, produce actual social behavior. It also applies the methodological concerns of The Analysis of Subjective Culture (1972): the section on culture and behavior draws on the subjective culture framework, and the book's attention to how different groups perceive the same behavior differently reflects that earlier program. In this sense, Interpersonal Behavior is a synthesis that pulls together Triandis's attitude research and his cross-cultural methodology into a single theoretical statement, making it a pivotal transitional work in his career.

It offers a conceptual framework that is intended to be testable, though Triandis deliberately made it difficult to reduce to a single empirical index. The model specifies variables and their relationships—intentions mediate between antecedents and behavior, habit and facilitating conditions moderate the intention-behavior link—but it does not provide a standardized measurement instrument. Triandis later acknowledged that because he intentionally created a 'grand theory,' developing a single index based on his model would be difficult . This has limited the model's direct empirical testing compared to simpler frameworks like the theory of reasoned action. However, its conceptual influence has been substantial, particularly in its inclusion of habit and facilitating conditions, which the theory of planned behavior later incorporated as perceived behavioral control.

The final chapter addresses practical implications in five domains: interaction across cultures, the employment interview, supervisor-subordinate relations, teacher-pupil relations, and marital relations . The publisher's description indicates the book was intended for undergraduate courses in social behavior and as a review for graduate students and professionals preparing research proposals . The practical chapters are applications of the theoretical model rather than standalone advice, consistent with Triandis's view that practical problems are best addressed by understanding the underlying behavioral determinants. Readers seeking a how-to manual will not find one; readers seeking a theoretically grounded account of why interpersonal problems arise and how they might be addressed within a unified framework will find the book's approach valuable.