Psychologic Models and Theories

List of most important psychologic models and theories

Four Temperament Theory

The four temperaments originate in Ancient Greek medicine.

Hippocrates (5th century BCE) proposed that health and personality are governed by four bodily fluids or “humors.”

Later, Galen (2nd century CE) systematized this theory and linked the humors to psychological traits.

Each temperament was thought to result from an excess of one humor: blood, yellow bile, black bile, or phlegm.

Though outdated medically, the four types—Sanguine, Choleric, Melancholic, and Phlegmatic—remain influential in personality theory.

Sanguinic

Element: Air

Qualities: Warm and moist

Personality: Social, energetic, talkative, lively, optimistic

Behavior: Enjoys people, easily distracted, creative, forgets obligations

Modern comparison: Extroverted and emotionally expressive

Choleric

Element: Fire Qualities: Warm and dry Humor: Yellow bile

Personality: Ambitious, leader-like, passionate, easily angered

Behavior: Goal-oriented, confident, aggressive, impatient, not easily discouraged

Modern comparison: Assertive, dominant, sometimes aggressive

Melancholic

Element: Earth Qualities: Cold and dry Humor: Black bile

Personality: Thoughtful, introspective, detail-oriented, serious

Behavior: Prone to sadness, perfectionistic, loyal, needs solitude, deep thinker

Modern comparison: Introverted and analytical

Phlegmatic

Element: Water Qualities: Cold and moist Humor: Phlegm

Personality: Calm, kind, peaceful, reliable

Behavior: Avoids conflict, patient, compassionate, steady, sometimes passive

Modern comparison: Relaxed and agreeable

Questionnaire 0

We’ll explore a simple two-question tool to reflect on your temperament.

1. Energy Direction (E or I):

E = I gain energy from being active, social, or in groups.

I = I gain energy from being alone, quiet, or reflective.

2. Response Style (F or A):

F = I react quickly, outwardly, and emotionally.

A = I stay calm, take time, and keep emotions inside.

Solution

GPT4o maps the 2 x 2 "answer space" onto the 4-temperament space in a following manner:

EF → Sanguine: Energetic, social, expressive

EA → Choleric: Driven, assertive, action-oriented

IF → Melancholic: Reflective, sensitive, thoughtful

IA → Phlegmatic: Calm, steady, harmonious

In four groups, discuss in what extent this attribution fits You and if it doesn't, why.

Renaissance & Early Modern

Renewed interest in Platonism and Hermetic soul cosmologies.

Descartes: radical dualism—soul (res cogitans) and body (res extensa).

Human soul seen as seat of reason, will, and self-consciousness.

Debates emerge over animal souls and mechanistic bodies.

Mystical and esoteric views on soul persisted alongside rationalism.

Soul increasingly tied to the concept of personhood.

Cogito ergo sum

"Accordingly, seeing that our senses sometimes deceive us, I was willing to suppose that there existed nothing really such as they presented to us; And because some men err in reasoning, and fall into Paralogisms, even on the simplest matters of Geometry, I, convinced that I was as open to error as any other, rejected as false all the reasonings I had hitherto taken for Demonstrations; And finally, when I considered that the very same thoughts (presentations) which we experience when awake may also be experienced when we are asleep, while there is at that time not one of them true, I supposed that all the objects (presentations) that had ever entered into my mind when awake, had in them no more truth than the illusions of my dreams. But immediately upon this I observed that, whilst I thus wished to think that all was false, it was absolutely necessary that I, who thus thought, should be something; And as I observed that this truth, I think, therefore I am, was so certain and of such evidence that no ground of doubt, however extravagant, could be alleged by the Sceptics capable of shaking it, I concluded that I might, without scruple, accept it as the first principle of the philosophy of which I was in search."

(Rene Descartes, Discourse on the Method, 1637)

Empiricism and Materialism

Soul increasingly reduced to observable mental or bodily processes.

Locke: denies innate ideas—soul as tabula rasa, a passive receiver. Start of the NATURE / NURTURE debate.

Hume: rejects a persistent self; mind is a bundle of perceptions.

La Mettrie: human soul is an effect of bodily mechanisms (*L'homme machine*).

Diderot and French materialists view soul as an illusion of matter in motion.

Mind-body dualism increasingly replaced by monist materialism.

L'homme machine

The human body is a machine which winds its own springs. It is the living image of perpetual movement. Without food, the soul pines away, goes mad, and dies exhausted. ...[H]eavy food makes a dull and heavy mind whose usual traits are laziness and indolence. ... everything depends on the way our machine is running.

(Julien Offray de La Mettrie, 1747)

Associationism

Soul or mind functions through the association of ideas.

David Hartley: vibrations in nerves correspond to mental associations.

Mind explained through natural laws, not metaphysical substances.

Emphasizes memory, habit, and experience over rational soul.

Bridge between empiricism and early psychology.

Shift from soul as essence to mind as structure of learned relations.

Phrenology

Franz Joseph Gall proposed that mental faculties were localized in the brain.

Bumps on the skull supposedly indicated personality traits.

Phrenology gained popular appeal in 19th-century Europe and America.

Although flawed, it encouraged anatomical and neurological research.

Foreshadowed modern brain imaging and cognitive neuroscience.

Psychophysics

Gustav Fechner studied the quantitative relationship between stimulus and sensation.

"psycho-physics is an exact doctrine of the relation of function or dependence between body and soul" (Elemente der Psychophysik, 1860)

His law: sensation increases logarithmically with stimulus intensity.

Considered one of the founders of experimental psychology.

Merged philosophy and empirical science through measurement.

Inspired later studies of perception and thresholds.

Weber-Fechner's Law

Weber's Law: The minimum increase of stimulus which will produce a perceptible increase of sensation is proportional to the pre-existent stimulus

Experimental Memory Research

Hermann Ebbinghaus pioneered systematic study of memory.

Used nonsense syllables to avoid prior associations.

Identified the forgetting curve and spacing effect.

Demonstrated that memory could be studied experimentally and quantitatively.

His methods set standards for future cognitive research.

Forgetting curve

Describes how information is lost over time when there is no attempt to retain it.

The curve shows a steep drop in memory shortly after learning, then a slower decline.

After about 20 minutes, around 40% of new information is forgotten.

After one day, more than 60% can be lost without review.

The curve flattens over time—what is retained tends to stay longer.

Regular review or reinforcement can drastically reduce forgetting.

Serial Position Effect

Discovered by Hermann Ebbinghaus and later formalized by modern memory researchers.

Describes how the position of an item in a sequence affects its likelihood of being recalled.

Primacy effect: early items are remembered better due to more rehearsal time.

Recency effect: late items are remembered better because they are still in short-term memory.

Items in the middle are most likely to be forgotten.

This effect creates a U-shaped curve when recall probability is plotted against position.