IB Psychology SLTopic 2 — Health ProblemsPaper 1 & 2Learning approach~10 min read
Social Learning as an Explanation of Obesity
Here is a finding that surprises everyone the first time they meet it: your friends predict your body weight better than your husband or wife does. That should not happen if this were only about shared meals — and working out why it happens is the whole point of this page.
📚 What you need to know
Social learning theory (SLT) was proposed by Bandura (1972) as a development of behaviourism.
Behaviourism says the environment shapes us; SLT adds that we learn by watching other people.
Four principles: observation, imitation, social contexts, vicarious reinforcement.
The four mediational processes are ARRM: Attention, Retention, Reproduction, Motivation.
Attention and retention give learning; reproduction and motivation give performance.
Friendship groups can act as role models, developing norms around food choices and activity levels.
Christakis & Fowler (2007) is the study, and the ordering of its results is the key detail.
The four principles
Observation. Children learn by watching role models — parents, teachers, older siblings, celebrities. Role models usually have status, influence or qualities the child admires.
Imitation. Behaviours seen in role models get copied, especially when they look rewarding or admirable.
Social contexts. Learning happens through the environment: home, school, peer groups.
Vicarious reinforcement. Watching someone else be rewarded increases the chance you copy them. Seeing a sibling praised for tidying their room motivates another child to do the same, because they want the same reward.
That last one is the engine of SLT. You do not need to be rewarded yourself. Watching it happen to someone else is enough.
Mediational processes: ARRM
SLT highlights the cognitive processes that sit between stimulus and response. This is what separates it from plain behaviourism, and it is worth learning as two halves rather than four items.
The split between learning and performance is why a behaviour can appear months after it was observed. If you only ever look for immediate copying, you will conclude nothing was learned.
Applying it to obesity
According to SLT, people learn by observing and imitating role models. In the context of obesity, friendship groups can act as those role models.
Friends often share similar appearances, habits and interests.
Groups develop norms — around food choices and activity levels — which members follow in order to feel included.
This can lead to the spread of obesity within social networks.
🔬 Christakis & Fowler (2007)
Tracking obesity through a social network over three decades
AIM
To investigate how obesity spreads through social networks such as friends, siblings and spouses.
PARTICIPANTS
12,067 people from the Framingham Heart Study, assessed between 1971 and 2003.
PROCEDURE
Participants’ BMI was measured. Statistical models then examined whether obesity in one person was linked to obesity in their friends, siblings, spouse or neighbours.
RESULTS
If a friend was obese, a person’s risk rose by 57%. For a sibling it rose by 40%, and for a spouse by 37%. The strongest effect of all was between female same-sex friends.
CONCLUSION
Obesity can spread through social bonds, particularly within close female friendship groups.
Spouses eat the same meals from the same fridge. Friends often do not. If shared diet were the whole explanation, the spouse bar should be the tallest — and it is the shortest.
Build your answer around that comparison and you will stand out. The ordering friend > sibling > spouse is hard to explain through shared environment, and easy to explain through social learning: friends are people you choose and want to be like. Siblings and spouses you share a kitchen with. Influence beats proximity.
The rival explanation you should name
There is a serious alternative called homophily: people choose friends who are already similar to them. If so, the friendship did not spread anything — similar people simply found each other. This is the same correlation problem in a new outfit, and naming it is exactly the kind of evaluation that earns top marks.
Evaluating social learning and obesity
Strengths
Limitations
SLT offers a more rounded explanation than behaviourism, considering role models, social context and mediational processes.
SLT cannot explain why not all observed behaviours are imitated — friends in the same group often have very different BMIs.
It is less deterministic, since individuals have some control over whether they imitate what they see.
Obesity is multifactorial. Biological, genetic and socioeconomic factors also play a role, so SLT alone cannot fully explain it.
Useful for public health campaigns that target group norms rather than individuals.
Homophily offers a competing explanation for the same network data.
Christakis & Fowler used a very large sample tracked over three decades.
Data drawn from one town’s heart study raises questions about sampling bias.
Linking to the concepts
Perspective: obesity cannot be explained by a simple social learning model alone. There may be a biological basis such as hormonal dysfunction. It could also result from negative self-schemas leading to eating for comfort. And social media pressure to look a certain way can create cognitive dissonance — wanting an impossible body shape — which may itself lead to comfort eating as a form of self-medication.
Bias: with a large sample collected over decades, bias will inevitably affect validity and reliability. How consistent were the measures? Was BMI recorded the same way for every participant? Were records kept properly? And is there sampling bias, given the data comes from a single community study?
EXAM ANSWER
Discuss social learning theory as an explanation of one health problem. [22 marks]
Theory first, with the cognitive bit included
Bandura’s SLT: behaviour is learned by observing role models, filtered through ARRM, and strengthened by vicarious reinforcement.
Apply it to the health problem
Friendship groups act as role models and set norms about food and activity, which members follow to stay included.
Evidence, ordered deliberately
Christakis & Fowler: friend +57%, sibling +40%, spouse +37%; strongest between female same-sex friends.
Use the ordering as your argument
Spouses share a diet but rank lowest, which fits social influence better than shared environment.
Then give the counterHomophily: similar people may simply become friends, so the network may reflect selection rather than spread.
Conclude: strong evidence for social influence, weak proof of directionusing a study’s own pattern as your argument is far better than quoting it
💡 Exam tips
Always include ARRM. It is what makes SLT cognitive rather than pure behaviourism, and examiners look for it.
Explain vicarious reinforcement with an example. One sentence, easy marks.
Quote all three percentages in order. The order is the argument.
Name homophily. Very few candidates do, and it shows genuine understanding of correlation.
The learning-versus-performance split explains delayed imitation. Useful in almost any SLT question.
This study also works for research methods, since it is a large longitudinal correlational design.
⚠ Common mix-ups
Saying obesity is “contagious”. Behaviours and norms spread; the condition itself is not an infection.
Reading +57% as a 57% chance. It is a 57% increase in existing risk, not an absolute probability.
Confusing vicarious with direct reinforcement. Vicarious means the reward happened to someone else.
Mixing SLT up with operant conditioning. SLT adds observation and mediational processes.
Forgetting Bandura’s date. 1972 in this context, as a development of behaviourism.
Ignoring biology entirely. The mark scheme rewards recognising that obesity is multifactorial.
Up next: Stress, Cortisol and Weight Gain — the last piece of Health Problems, and the one that finally brings biology back into a topic that has been sociocultural for four pages.
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