Robert Jay Lifton, a psychiatrist and psychohistorian best known for his studies of the psychological effects of extreme trauma, totalitarianism, and ideological zeal, developed several influential psychological concepts:

• Thought-Terminating Cliché: Short, catchy, folk-wisdom phrases or slogans used to prematurely end critical analysis and suppress complex thinking or debate (e.g., "it is what it is" or "God works in mysterious ways").

• Psychological Doubling: The division of the self into two functioning wholes—a primary prior self and a secondary self—enabling an individual to participate in cruel, unethical, or destructive behaviors while maintaining a normal self-image outside of that context (e.g., Nazi doctors performing experiments while remaining attentive family men).

• Psychohistory: An interdisciplinary approach combining psychoanalytic psychology with historical analysis to examine the psychological motivations behind historical events, leaders, and mass movements.

• Protean Self: A flexible, fluid, and adaptable model of identity that continually changes and reshapes itself in response to rapid technological, social, and cultural shifts in the modern world, as opposed to a fixed or static personality structure.

• Psychic Numbing: A diminished capacity or inability to feel or react emotionally, functioning as a psychological defense mechanism against severe trauma, overwhelming disaster, or the ongoing threat of extreme destruction (such as nuclear war or genocide).

• Symbolic Immortality: The human psychological drive to transcend physical mortality by seeking continuity through five traditional modes: biological (children/descendants), creative/works, theological/spiritual, natural (reconnection with nature), or experiential (transcendent states).

• Illusion of Invariance: An unconscious, defense-driven belief that one's surrounding environment, culture, and institutions are permanent and immune to collapse, which protects the mind from confronting catastrophic change or existential fragility.

• Formative Psychology: An approach to human psychology emphasizing that the mind is constantly engaged in creating and revising internal forms, images, and symbols to construct meaning out of raw experience and trauma.

• Milieu Control: The total control or manipulation of an individual's communication and social environment by a group or system to strictly regulate what they hear, read, write, and experience.

• Loading the Language: The heavy use of a specialized, highly compressed, and emotionally charged jargon that restricts clear thinking, enforces group conformity, and categorizes complex human experiences into rigid, polarized terms.

• Sacred Science: An ideological framework that claims absolute scientific truth and ultimate moral authority, placing its core tenets above empirical questioning or criticism.