Conway girls, 1953

Conway girls, 1953

An appreciation of emotion as a Way of Knowing would not be complete without a consideration of human dispositions. Psychologists have long studied the systematic ways in which individuals differ. Psychologist Daniel Nettle writes (2008) that consensus has emerged in recent decades that five personality traits: “extroversion, neuroticism, conscientiousness, openness and agreeableness, define five axes along which all individuals fall.” According to Nettle, psychologists view these personality traits:

as thermostats within the brain, each regulating a range of behaviours and attitudes. Some of these behaviours and attitudes seem to be linked. For example, people who are highly competitive and like loud music and travel tend also to have high sex drives. People who have a specific phobia tend to worry a lot about other things too, and they are more prone to depression… From such correlations, we infer that there are a limited number of thermostats, each working independently.

Nettle reports that “[n]euroscientists are now beginning to relate the big five to the brain”:

Take neuroticism. Neuroscientists know which parts of the brain are involved in the response to threats: there's a circuit involving a structure called the amygdala… There is… evidence that the size of the amygdala is proportional to a person's neuroticism score… (Neuroscience and Biobehavioral Reviews, Vol. 30: 511). Amazingly, the simple, self-rating questionnaires used by personality psychologists actually turn out to measure something about the nervous system that can be verified through objective scientific techniques.

Image source: Nettle, David: The personality factor: What makes you unique? New Scientist: February 9, 2008.

Image source: Nettle, David: The personality factor: What makes you unique? New Scientist: February 9, 2008.


This session requires use of a computer lab or class set of laptops. Students work in pairs. Students read the consent form and research background information, then each complete the Big Five Personality Test for themselves with the other observing. Still in pairs students consider the following questions:

How accurate was your own test feedback?
Be honest, did being observed by your partner influence your responses? 
Was your test feedback objective? Did the algorithm merely rearrange and regurgitate your own responses to the questions or did it reveal something new? 
What makes the “Big Five” test superior to the numerous personality quizzes popular on the internet like “What girl scout cookie are you?” 

Next, the whole class should reconvene. Students are called upon to read the following passages aloud. Afterwards, the guiding questions should be tackled. 

The final broad knowledge issue question is quite challenging and could represent a high tide mark for students about half way through the TOK course.


Psychology aspires to being a hard science whilst conceding the daunting complexity of its subject matter when compared to chemistry or physics. The selections from the David Nettle article, and the background reading supporting the Big Five Personality Test, point to a high degree of internal consistency and thorough grounding in brain imaging, data from brain damaged patients and observed correlations in many thousands of subjects. Students already encountered applicable factors like clarity, coherence, correspondence and absence of contradiction or counterevidence in their critique of Justified True Belief. 

This unit of inquiry links to Science as an Area of Knowledge and, in particular, Popper and Falsifiability.

Four humors in Tudor medicine 

Four humors in Tudor medicine 


A traditional theory of physiology in which the state of health―and by extension the state of mind, or character ―depended upon a balance among the four elemental fluids: blood, yellow bile, phlegm, and black bile. These were closely allied with the four elements. Their correspondence is described as follows:

The “humours” gave off vapors which ascended to the brain; an individual's personal characteristics (physical, mental, moral) were explained by his or her “temperament,” or the state of that person's humours. The perfect temperament resulted when no one of these humours dominated. In Shakespeare's Julius Caesar (V.v.74-76), in which Antony eulogizes Brutus:  

His life was gentle, and the elements
So mix'd in him that Nature might stand up
And say to all the world, "This was a man!"

* Source for this material: C. Hugh Holman, ed. (1980: 220) A Handbook to Literature, 4th ed. Bobbs-Merrill, Indianapolis.


What are the five Confucian elements?
What are some of the differences and commonalities between Chinese and Western astrology?
What is the relationship between astrology and astronomy? 
What is the relationship between alchemy and chemistry?

What do you conclude about pre-scientific grids or frames that attempt to understand human nature and the physical world? Are they false?