Human Sciences — Study Guide
Use this as a review reference for the Sciences major essay. These are topics and examples you may wish to use in your essay.
Scope: What Counts as a Human Science?
Systematic, empirical study of human behaviour and society.
Core disciplines: psychology, economics, sociology, anthropology.
Some fields that sound scientific do not qualify in TOK:
- Political science ≠ politics — political science is a human science; politics is not
- World Religions — not a science
- Business Management — borderline case
The defining contrast with natural sciences: human sciences study things that depend on human agreement. The natural world (hydrogen, gravity) would exist without humans. The subject matter of the human sciences — money, marriage, borders — would not.
The Observer Effect
The act of observation changes what is being observed. This is central to the human sciences in a way it is not in the natural sciences.
| Variant | Definition |
|---|---|
| Observer effect (general) | Being observed changes behaviour |
| Hawthorne effect | Workers at the Hawthorne Works produced more whenever they were observed, regardless of what conditions were changed |
| Goodhart’s paradox | When a measure becomes a target, it ceases to be a good measure |
| Probe effect | The instrument used to measure something disturbs the thing being measured |
| Observer expectation effect | The researcher’s expectations influence how they interpret what they observe |
Psychology: Controlled Experiments
Peterson & Peterson (1959) — classic short-term memory experiment: - Participants were given a 3-letter sequence, then asked to count backward by threes (to prevent rehearsal) - Memory decays rapidly: most is forgotten within 18 seconds without rehearsal - Illustrates the use of a controlled lab setting (“simplified replica”)
Atkinson-Shiffrin model of memory: sensory store → short-term memory → long-term memory
Ecological validity: does a lab finding reflect what actually happens in real life? Lab experiments gain control but lose ecological validity.
Economics: Models
Circular flow of income — simplified model showing money moving between households and firms; exports/imports and government can be added
MONIAC (1949) — a physical, hydraulic machine built by Bill Phillips modelling the UK economy using water flows; tanks and pipes represented different economic sectors
Kahneman and Tversky — founders of behavioral economics; showed that human economic decisions are systematically irrational: - Prospect theory — people are risk-averse when facing gains but risk-seeking when facing losses (e.g., the $100 certain vs. coin flip for $400 example) - Availability heuristic — we overestimate the likelihood of things that come easily to mind (gun crime vs. respiratory disease deaths)
The tension: classical economics assumes rational actors; behavioral economics shows people are predictably irrational.
Sociology: Surveys, Questionnaires, Interviews
| Method | Description |
|---|---|
| Survey | Uses a fixed scale (e.g., Likert 1–5); produces quantitative data |
| Questionnaire | Open-ended written questions; richer but harder to analyse |
| Structured interview | Same questions for all respondents; easy to compare |
| Semi-structured interview | Core questions fixed, follow-ups flexible |
| Unstructured interview | Interviewer-led; flexible, but more prone to researcher bias |
| Focus group | Group interview around a shared characteristic |
Leading questions — questions that imply an answer or assume a fact; undermine validity.
Qualitative vs. quantitative: qualitative methods produce rich text-based data; quantitative methods produce numerical data amenable to statistical analysis.
Anthropology: Participant Observation
Participant observation — the researcher embeds themselves in the group they are studying.
Non-participant observation — researcher observes from a distance: - Overt: subjects know they are being observed - Covert: subjects are unaware; raises ethical concerns
Margaret Mead — studied adolescence in Samoan girls; later criticised by Derek Freeman, who argued she had let her acceptance into the community cloud her judgment and that subjects had fabricated their accounts.
Robin Nagle — spent years working for the NYC Department of Sanitation to study trash culture from the inside. Example of deep participant observation that humanised overlooked workers and revealed inequalities in the city’s waste infrastructure.
Challenge: becoming part of the group can undermine objectivity.
| Method | Strength | Limitation |
|---|---|---|
| Participant observation | Very detailed, hands-on knowledge from the point of view of a participant | Tension between being a participant (perspectival) and an observer (supposedly neutral) |
| Non-participant observation | Reduces the effect observation has on subjects’ behaviour | Ethical concerns around covert observation |
| Case study | Rich data; ecologically valid; allows triangulation | Cannot be generalised; difficult to replicate |
Bias vs. Perspective
This distinction is central to the unit and frequently confused in TOK essays.
Bias — a systematic distortion of the truth. There must be a truth from which the knower deviates consistently.
Perspective — a point of view. Different perspectives can all be valid; having a perspective does not mean anything is distorted.
“Often, students write ‘bias’ when they mean ‘perspective’. Save ‘bias’ for situations where there is a clear truth of the matter and a knower deviates systematically from it.”
Researcher biases:
| Bias | Description |
|---|---|
| Confirmation bias | Seeking or interpreting evidence to confirm a preexisting belief |
| P-hacking | Manipulating data collection or analysis to achieve statistical significance |
| Funding bias | Pressure from a funding source to publish only favourable results |
| Publication bias | Journals prefer to publish positive results; negative results are underreported |
| Selection bias | A sample with systematic characteristics that make it unrepresentative |
Participant biases:
| Bias | Description |
|---|---|
| Expectancy effect | Participant responds in a way they think the researcher wants |
| Screw-you effect | Participant acts against the researcher’s hypothesis to sabotage results |
| Social desirability effect | Participant responds in a “socially acceptable” way rather than honestly |
| Observer effect (reactivity) | Participant behaves differently because they know they are being observed |
Key Vocabulary
| Term | Definition |
|---|---|
| Ecological validity | How well a study reflects real-life conditions |
| Random sampling | Every member of the population has an equal chance of being selected |
| Stratified sampling | Sample built to match the demographic profile of a population |
| Triangulation | Using multiple methods to cross-check findings |
| Replication | Repeating a study to verify results |
| Double-blind | Neither researcher nor participant knows who is in which condition |
| Reflexivity | Researcher reflects critically on how their own position shapes their work |
| Inductive generalisation | A general claim supported by statistical evidence |
| Social fact | Something that exists only because people collectively agree it does |
| Participant observer | A researcher who embeds themselves in the group they are studying |
When writing about the human sciences, use examples from your DP subjects (psychology, economics, sociology). Anthropology can be treated like history in TOK — it is culture-specific and its findings are hard to generalise. The observer effect and the lack of a universal method are the two most productive angles for comparing the human sciences to the natural sciences.
Social Facts
John Searle’s concept: some things exist only because people collectively agree they do.
Examples: money has value, marriage exists as a legal institution, countries have borders.
Social facts are different from natural facts — the boiling point of water does not depend on anyone’s agreement.