Social Psychology Part 3 – Key Concepts, NYU Social Psychology
Difficulty: Intermediate | Prerequisites: Familiarity with basic social psychology concepts (attitudes, group dynamics, prosocial behaviour).
This unit sits at the intersection of biology, culture and group perception. It covers how environments and genes interact to shape behaviour, how people decide whether to help in emergencies, and how we sort others into groups (sometimes on almost no basis at all). If you have not yet reviewed the fundamentals of prosocial behaviour and intergroup relations from earlier units, do that first.
People shape their environments, and those environments shape them back (niche construction, epigenetics). Helping in emergencies is not automatic; it follows a decision tree where bystanders can stall at any step. We perceive some groups as more "real" than others (entitativity), and even trivial group boundaries are enough to trigger favouritism (minimal group paradigm).
Niche construction
The idea that organisms (including humans) actively modify their environments through culture, technology or institutions, and those modified environments in turn shape psychological development and behaviour.
Think of it as: people build the world they live in, and the world they built then changes how they think and act.
Decision Tree Model (Latané and Darley)
A sequential model of bystander intervention that breaks the decision to help in an emergency into discrete steps: noticing the event, interpreting it as an emergency, assuming personal responsibility, knowing how to help, and deciding to act.
In simple terms, this means: helping is not one decision but a chain of them, and a "no" at any link stops the whole thing.
Epigenetics
The study of how environmental factors (stress, diet, social experience) influence gene expression without altering the underlying DNA sequence. Life experiences can switch genes on or off, affecting biology and behaviour across a lifespan and sometimes across generations.
Think of it as: your DNA is the script, but epigenetics decides which lines get read aloud.
Entitativity
The degree to which a collection of people is perceived as a coherent, unified group rather than a loose set of individuals. Factors that increase entitativity include similarity among members, frequent interaction, shared goals and a common fate.
In simple terms, this means: how "real" or "groupy" a group feels to an outside observer.
Minimal Group Paradigm
An experimental method (developed by Henri Tajfel) in which participants are assigned to groups on entirely arbitrary criteria, such as a coin toss or preference for one painting over another. Even these meaningless distinctions reliably produce ingroup favouritism and outgroup discrimination.
Think of it as: give people the thinnest possible reason to see "us" and "them," and they will still play favourites.
Humans do not simply adapt to environments; they actively reshape them through technology, institutions and cultural practices.
Those reshaped environments then create new selection pressures and developmental contexts.
Example: the invention of dairy farming changed diets, which over generations selected for lactose tolerance in certain populations.
In psychology, this means culture is not just a backdrop. It is a cause of psychological variation as much as a consequence of it.
Latané and Darley proposed five sequential steps a bystander must pass through before helping:
Notice the event.
Interpret the event as an emergency.
Accept personal responsibility for acting.
Know the appropriate form of assistance.
Decide to act.
Failure at any single step means no help is given.
Key blockers at each step:
Step 1: Distraction, sensory overload (urban environments).
Step 2: Pluralistic ignorance, where everyone looks calm so no one interprets it as serious.
Step 3: Diffusion of responsibility, where the presence of other bystanders reduces each person's felt obligation.
Environmental factors such as chronic stress, nutrition and early caregiving can add or remove chemical tags (e.g. methyl groups) on DNA.
These tags regulate whether genes are expressed ("switched on") or silenced, without changing the DNA sequence itself.
Relevance to social psychology:
Adverse childhood experiences can alter stress-response gene expression, affecting temperament and social behaviour.
Some epigenetic changes may be transmitted across generations, meaning a parent's environment can influence offspring biology.
Not all collections of people feel equally "group-like" to observers.
High-entitativity groups are perceived as coherent units. Characteristics include:
High similarity among members.
Frequent interaction.
Common goals or shared fate.
Clear boundaries (you are in or you are out).
Low-entitativity aggregates (e.g. people waiting at a bus stop) are not perceived as meaningful groups.
Entitativity matters because it affects how we attribute behaviour: actions by a high-entitativity group are more likely to be seen as intentional and representative of the group as a whole.
Tajfel's experiments showed that people assigned to groups on trivial, meaningless criteria still:
Allocated more resources to ingroup members.
Evaluated ingroup members more favourably.
Sometimes maximised the difference between groups rather than maximising their own group's absolute gain.
This suggests ingroup favouritism does not require competition, history or real differences; mere categorisation is sufficient.
The finding underpins Social Identity Theory: people derive part of their self-esteem from group memberships, so even arbitrary groups become psychologically meaningful.
Niche construction explains why urban design, school policy and workplace culture are not neutral containers but active forces shaping how people develop. City planners who add green space are, in effect, constructing a psychological niche.
The Decision Tree Model is the reason emergency-response training tells people to point at a specific bystander and say "You, call 999." It short-circuits diffusion of responsibility at Step 3.
Epigenetics is central to public health arguments for early childhood intervention. Programmes like Head Start aim to buffer adverse environments before stress-related epigenetic changes become entrenched.
Entitativity helps explain why corporate teams with clear shared goals feel cohesive, while loosely assembled committees often do not, and why observers judge tight-knit groups more harshly for a single member's misconduct.
The Minimal Group Paradigm is the foundation for diversity training that targets unconscious categorisation. If favouritism kicks in from a coin toss, it certainly operates along race, gender and nationality lines.
Students often think epigenetics means genes are changed. It does not. The DNA sequence stays the same; what changes is whether and how much a gene is expressed.
Students frequently confuse diffusion of responsibility with pluralistic ignorance. Diffusion of responsibility is about who should act (Step 3). Pluralistic ignorance is about what is happening (Step 2). Both reduce helping, but at different stages of the decision tree.
It is a common mistake to assume the Minimal Group Paradigm only works in the lab. The underlying mechanism, mere categorisation triggering favouritism, operates in real social settings wherever group labels exist.
Students sometimes think entitativity is a property of the group itself. It is a property of the perceiver's judgement. The same collection of people can look high-entitativity to one observer and low-entitativity to another, depending on the cues they notice.
⚠️ Be able to list and explain all five steps of the Latané and Darley decision tree, and name the psychological barrier at each step.
⚠️ Know the difference between epigenetic change and genetic mutation. Exam questions love to test whether you understand that DNA is not altered.
⚠️ Tajfel's Minimal Group Paradigm is a classic study. Expect questions about what it demonstrates (mere categorisation is sufficient for favouritism) and what it rules out (competition, prior history, real group differences).
⚠️ Entitativity is often tested through scenarios: "Which of the following groups would be perceived as highest in entitativity?" Look for similarity, interaction and shared goals.
⚠️ Niche construction may appear in essay prompts asking you to discuss the relationship between culture and psychology. It is the mechanism through which culture feeds back into biological and psychological development.
True or false: Epigenetics involves permanent changes to the DNA sequence. (False. The sequence is unchanged; gene expression is what shifts.)
Fill in the blank: In the decision tree model, ______ occurs when bystanders look to each other for cues and everyone appears calm, so no one acts. (Pluralistic ignorance.)
True or false: The Minimal Group Paradigm shows that real conflict between groups is necessary for ingroup favouritism to appear. (False. Mere categorisation is enough.)
Fill in the blank: A group high in ______ is perceived as a coherent, unified entity. (Entitativity.)
True or false: Niche construction is a one-way process in which environments shape people but people do not shape environments. (False. It is bidirectional.)
Q: Name the five steps in Latané and Darley's decision tree model of bystander intervention.
A: (1) Notice the event, (2) interpret it as an emergency, (3) assume personal responsibility, (4) know the appropriate form of help, (5) decide to act.
Q: What is the key distinction between epigenetic change and genetic mutation?
A: Epigenetic change alters gene expression (which genes are active) without modifying the DNA sequence. Genetic mutation changes the sequence itself.
Q: A researcher assigns participants to Group A or Group B based on a coin flip, then measures resource allocation. What paradigm is this, and what does it typically demonstrate?
A: This is the Minimal Group Paradigm. It typically demonstrates that even arbitrary, meaningless group distinctions produce ingroup favouritism and outgroup discrimination.
Q: How does entitativity influence attribution of group behaviour?
A: When a group is high in entitativity (perceived as a coherent unit), observers are more likely to see individual members' actions as intentional, coordinated and representative of the group as a whole.
Q: Explain how niche construction creates a feedback loop between culture and psychology.
A: Humans modify their environments through cultural practices and institutions (e.g. schooling, agriculture, technology). These modified environments then shape the developmental contexts in which future generations grow up, influencing their cognition, emotion and behaviour, which in turn drives further environmental modification.
The Decision Tree Model connects directly to the broader bystander effect literature and to Latané's work on social impact theory. If you are revising prosocial behaviour, the decision tree is the mechanistic backbone.
Epigenetics links to developmental psychology and health psychology, particularly discussions of adverse childhood experiences (ACEs) and intergenerational trauma. It also connects to the nature-versus-nurture debate by showing the two are not independent.
The Minimal Group Paradigm is the empirical foundation for Tajfel and Turner's Social Identity Theory, which you will encounter in any unit on prejudice, stereotyping or intergroup conflict.
Niche construction, gene-culture co-evolution, bystander effect, bystander intervention, Latané and Darley, decision tree model, pluralistic ignorance, diffusion of responsibility, epigenetics, gene expression, methylation, entitativity, group perception, group cohesion, minimal group paradigm, Tajfel, ingroup favouritism, outgroup discrimination, mere categorisation, Social Identity Theory, intergroup bias, prosocial behaviour, NYU social psychology