The Trilogy of Mind...

Link to Hungarian translation by Elana Pavlet.

Link to Swedish translation by Weronika Pawlak.


The origins of psychology in Descartes' philosophy, which emphasized epistemology, or the nature of knowledge, and the work of the British empiricists, with their emphasis on the acquisition of knowledge through experience (and reflections on experience). As a result, scientific psychology has from the beginning been concentrated on problems of cognition -- sensation, perception, learning, memory, thinking (in various forms) and language. However, cognition is not the exclusive subject matter of psychology: psychology is concerned with emotion and motivation as well. These three domains constitute what Hilgard (1980) called the trilogy of mind.

What follows relies heavily on Hilgard's essay.

Scientific psychology has its origins in 19th-century psychophysics, but the field's history also includes a "philosophical" psychology that goes back at least to the early 18th century.

... in Early Modern Philosophical Psychology...

The very term psychology was revived by Christian Wolfe in his Psychologia Empirica (1732) and Psychologia Rationalis (1734). In these treatises, he offered a dual classification of the faculties of mind:

  • the facultas cognoscitova,having to do with knowledge and belief; and
  • the facultas appetiva, having to do with desire.

A little later, the philosopher Moses Mendelssohn, in his Letters on Sensation (1755) added affect, having to do with feeling and emotion, thus completing the tripartite classification of mental faculties, or functions.

The tripartite classification of mental faculties was codified by another philosopher, Immanuel Kant, in three treatises:

  • The Critique of Pure Reason (1781), concerning the intellect;
  • The Critique of Practical Reason (1788), concerning the will; and
  • The Critique of Judgment (1791), concerning feelings of pleasure and pain.

As Kant put it in the Critique of Judgment:

There are three absolutely irreducible faculties of the mind, namely, knowledge, feeling, and desire.

He went on:

The laws which govern the theoretical knowledge of nature as a phenomenon, understanding supplies in its pure a priori conceptions. The laws to which desire must conform, are prescribed a priori by reason in the conception of freedom. Between knowledge and desire stands the feeling of pleasure or pain, just as judgment mediates between understanding and reason....

By "irreducible", Kant meant that none of the three faculties was derived from either of the others. Each functions independently. As we shall see later, this point is controversial.

  • Some psychologists have offered theories of emotion and motivation that depend on cognitive appraisal: in these theories, at least, emotion and motivation are reducible to cognition.
  • But other psychologists have adopted Kant's view that there are at least some aspects of emotion and motivation that are, as he asserted, independent of cognition.

Still, as we shall also see later, cognition, emotion, and motivation can interact in interesting ways, as when emotional states serve as filters on cognition, and cognitive processes are employed to in emotional self-regulation.

Kant's classification was taken up by the "Scottish philosophers" of the 18th and 19th century, including Thomas Reid, Dugald Stewart, William Hamilton, and Thomas Brown. As far as the mind was concerned, the Scottish philosophy embraced a position of dualistic realism which held that the mind was aware of, and reacts to, the external world, but is also capable of reflecting on itself. The Scottish philosophers postulated some 37 "powers and propensities" of mind, which later formed the basis for the mental faculties in Gall's phrenology. But they also accepted the tripartite classification of mind as basic.

The Scottish philosophy was imported to America in the 18th and 19th centuries by John Witherspoon, James McCosh, Mark Hopkins, and E.W. Scripture.

Faculty psychology was eventually abandoned: Locke's associationism entailed a unified view of the mind, in which the various faculties were not separate "mental agents". While the faculty psychology was nativist in nature, associationism was empiricist: ideas originate either from sensation (experience) or reflection on sensation; the mind is passive in its reception of simple ideas, and ideas become associated with each other, forming complex ideas, through experience.

Nevertheless, the abandonment of faculty psychology had no effect on the tripartite classification of mind. Alexander Bain, a Scot who dominated 19th-century British psychology, embraced it in his two treatises, The Senses and the Intellect (1855) and The Emotions and the Will (1859). For Bain, there were three phenomena of mind:

  • feeling (emotion, passion, affection, and sentiment);
  • volition (will, action); and
  • thought (intellect, cognition).

But Bain thought that the first response to an event has the quality of a feeling.

... and in Modern Scientific Psychology

The trilogy of mind had its final expression in the purposive psychology of William McDougall, who postulated an instinct theory in opposition to British associationism. McDougall objected primarily to the passive, mechanistic view of mind implicit in associationism. He viewed mind as a more active agent. McDougall defined instincts as innate propensities, or energy sources, whose excitation by stimuli determined the immediate goal of thought and action.

For McDougall, mental activity consisted of a cycle:

  • a stimulus event excited an instinct, whose energy was aimed at a specific goal;
  • the excitation of an instinct created a perceptual disposition to attend to certain classes of (instinct-relevant) objects;
  • it also excited an emotional disposition in relation to the objects of perception;
  • and, finally, resulted in goal-directed behavior.

This cycle represents the entire trilogy of mind:

  • motivation, in terms of the activation of behavior and its direction toward a goal;
  • emotion, in terms of the subjective experience of arousal, pleasure, and displeasure, and its expression in behavior;
  • cognition, in terms of the mental representation of reality (real or imagined), as reflected in perception, attention, learning, memory, thinking, and language;
  • and ending in action.

McDougall's instinct theory, emotion and motivation were closely related:

  • approach and avoidance are analogous to pleasure and pain;
  • motivational states set the stage for emotional responses to events.

All of these -- cognition, emotion, and motivation -- are mental states, which can be represented in conscious awareness. All of them also have biological substrates, as well.

McDougall postulated 14 innate instincts as part of our phylogenetic heritage. Each was paired with a corresponding emotion, and each explained a particular type of behavior. Thus -- and this was its downfall -- the theory is completely circular: instincts are cited as the causes of behavior, and behavior is cited as the evidence for instincts.

For this and other reasons, the behaviorist revolution in psychology abandoned interest in the mind, to focus entirely on observable behavior. Watson and Thorndike made no reference to unobservable mental states.

Emotion and cognition were abandoned almost entirely, except:

  • Watson himself performed studies of conditioned emotional responses, as in the famous case of "Little Albert".
  • Edward C. Tolman, while embracing behavioral methodologies, including the study of animals, emphasized cognitive aspects of learning, especially expectations.

An interest in motivation was retained in certain "liberal" forms of behaviorism:

  • The "Stimulus-Response" learning theory proposed by C.L. Hull, and promoted by Spence, emphasized the role of drive in learning, and of drive-reduction in reinforcement.
  • Again, Tolman's "sign learning" approach emphasized the organism's expectation of reward.

But B.F. Skinner did away even with drive, and promoted a radical behaviorism that was concerned solely with tracing the functional relations between inputs and outputs. For Skinner, and other radical behaviorists, the organism was treated merely as a "black box" that connects stimulus inputs and response outputs. For Skinner and his confreres, there was no need to understand the organism's internal mechanisms, structures, processes, and states.

The New Look

New LookFor a very long time, then, an interest in emotion and motivation, if not cognition as well, resided mostly in the hands of psychoanalysts, and especially in the "neoFreudian" school that de-emphasized Freud's original theory of infantile sexuality. For psychoanalysts of all stripes, emotion and motivation played a dynamic role in the determination of the individual's experience, thought, and action -- and also colored the individual's cognitive processes as well. One important exception was the "New Look" in perception, promoted in the late 1940s and early 1950s by Bruner and his colleagues.

Bruner was a pioneering cognitive psychologist, but to some extent, the New Look was also influenced by psychoanalysis -- more the psychoanalytic ego psychology of Rapaport than the classical psychoanalysis of Freud, that thrust of which was that perception is not an autonomous cognitive process, but rather can be influenced by the perceiver's emotional and motivational states. So, for example, Bruner and Goodman (1947) demonstrated that poor children were more likely to overestimate the size of valuable coins (dollars and half-dollars, compared to pennies and nickels) than were rich children. And Bruner and Postman (1947) showed that thresholds for perceptual recognition varied depending on whether the stimulus words were emotionally salient. Some subjects showed lowered thresholds for such words, suggesting a "mental set" of perceptual vigilance; other subjects showed heightened thresholds, suggesting a mental set of perceptual defense. In either case, it was clear that the emotional significance of the stimuli were affecting even a basic cognitive operation as stimulus identification.

Many of the experiments inspired by the New Look didn't stand the test of time. Some had important methodological weaknesses, and the notions of perceptual defense and vigilance were criticized on theoretical grounds: it seemed impossible that the emotional connotations (or any other aspect ) of meaning of a stimulus could be processed before that stimulus had even been identified. Still, the core assertions of the New Look -- that mental states and processes intervened between stimulus and response, and that cognitive, emotional, and motivational processes interacted with each other in important ways -- stuck, and laid the foundation for both the cognitive revolution and the affective counterrevolution in psychology.

For Bruner's comments on the New Look and its relation to later developments, see:

  • Bruner, J. S., & Klein, G. S. (1960). The function of perceiving: New Look retrospect. In W. Wapner & B. Kaplan (Eds.),Perspectives in psychological theory: Essays in honor of Heinz Werner (pp. 61-77). New York: International Universities Press.
  • Bruner, J. (1992). Another look at New Look 1.American Psychologist, 47, 780-783.
  • Bruner, J. (1994). The view from the heart's eye: A commentary. In P. M. Niedenthal & S. Kitayama (Eds.),The heart's eye: Emotional influences in perception and attention (pp. 269-286). San Diego: Academic Press.

Affect and Motivation after the Cognitive Revolution

During the late 1950s and early 1960s, the "cognitive revolution" in psychology changed everything -- at least for cognition! Once Neisser's pioneering textbook on Cognitive Psychology was published, psychology departments began to offer a complete curriculum devoted to cognition, with separate courses on sensation, perception, learning, memory, thinking, and language; and whole new graduate programs developed devoted to cognitive psychology.

At least implicitly, the cognitive revolution reinstated the doctrine of mentalism -- that behavior was caused by the organism's mental states. But its interest in mental life was almost exclusively focused on cognitive states: the organism's perception of of the present situation, its memory of past experiences, and its expectations of the future. Some cognitive psychologists defined "cognition" very broadly, to include both emotional and motivational states. But for the most part, laboring under the influence of the computer metaphor of the mind, "cognition" was defined narrowly in terms of human information processing.

This situation began to change in the early 1960s, with the development of an expressly cognitive viewpoint within social psychology. Social psychology had always been interested in emotion: its central concept was the attitude, or the individual's positive or negative evaluation of some object or idea. Social psychology was also interested in phenomena such as interpersonal attraction, aggression, and altruism that have a heavy emotional and motivational overlay. And so, gradually, largely reflecting the influence of social psychologists, psychology recovered an interest in emotion and motivation.

Two events, especially, brought cognition and emotion together:

  • Abelson (1963) developed a computer simulation of "hot" cognition -- that is, cognitions that are heavily laced with emotion and motivation.
  • Even more influential, Schachter and Singer (1962) introduced a "cognitive constructivist" theory of emotion -- that emotional states like happiness and anger were the products of the individual's interpretation of the situation in which he or she became physiologically aroused.

Very quickly thereafter, psychologists (and not just social psychologists) became interested in emotion and motivation again. But this renewed interest in emotion and motivation had an interesting feature: it violated Kant's prescription that cognition, emotion, and motivation were "irreducible faculties of mind" -- that is, fundamentally independent of each other.

  • For Abelson, emotional and motivational states could affect cognitive states -- much as, for McDougall, emotion and motivation seemed to be opposite sides of the same coin.
  • More critically, for Schachter and Singer, emotional states were a product of cognitive activity -- precisely because the emotion flowed from the individual's (cognitive) interpretation of the circumstances under which he or she became physiologically aroused.

As a result, and somewhat paradoxically, the renewed interest in emotion (and motivation) tended to undercut the status of both emotion and motivation within psychology. If emotion and motivation were products of cognition, then cognition reigned supreme within the field. As a result, no department of psychology, anywhere, offers as extensive a menu of courses on emotion and motivation, much less entire graduate programs devoted to them; as they all do for cognition.

This situation, too, was ripe for revolution, and what might be called an "affective counterrevolution" in psychology has attempted to dethrone cognition from its current position, and return to a situation where emotion and motivation are co-equal in status with cognition within the field of psychology.

That counterrevolution has not succeeded yet, but even so we know a great deal more about emotion and motivation than we used to. In the pages that follow, I present a summary of what we know about emotional and motivational processes.


Links to separate pages on each element in the trilogy of mind:

This page last revised 06/28/2014.