Kurt Lewin’s behavior equation is “B = f(P, E)”. It states that an individual’s behavior (B) is a function (f) of the the person (P), including their history, personality and motivation, and their environment (E), which includes both their physical and social surroundings.

Summary by The World of Work Project

Lewin’s Behavior Equation: A Simple Model Of Human Behavior

As many of you know, we often think that Kurt Lewin got there first, wherever there is. We also think he usually got there more clearly and simply than most people. The same pretty much holds true here in relation to modelling behavior as well.

Lewin's Behavior Model is B=f(B,E)

Kurt Lewin’s behavior model is very simple, but we think it elegant. Put simple is says that an individual’s behavior is a function of that individual and their environment. Of course, we acknowledge this model looks totally simple, so much so that it’s just common sense. We’re not sure that it was at the time though.

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The model is actually slightly more complicated than it looks because of the range of information included within the P (people) and E (environment) factors.

In this model “P” includes the entirety of the person including their past, their present, their expectations of the future, their personality, their capabilities, their motivations, their desires, and so on. And “E” includes all aspects of the person’s environment at the time of any behavior including their physical environment, but also their social environment and contexts.

One way to think about this is that the exact same individual can behave in very different ways if their environment changes and, similarly, an individual can behave in very different ways in the exact same situation as they change as a person over time.

Lewin's Behavior Model may explain messy rooms, like this one
We behave differently in different environments… Mess may lead to more mess…

One key take away from Lewin’s Behavior Model is that if we’re looking to change someone’s behaviors, then we can do so through changing either them as a person or their environment. The same is true of populations of people as well.

Learning More

If you’d like to learn more about behavior and behavior change, we suggest starting with the Behavior Change Wheel. The transtheoretical model of behavior change is also interesting. For wider learning we’d suggest looking into human motivation theories as well as human habits.

It’s also worth considering how individuals and organizations influence the behaviors. This can be done through addictive product design, or through influencing as described in the Fogg model. We’ve recorded a podcast on the topic of influencing consumer behavior which may be of interest for some readers:

The World of Work Project View

As ever, we think Kurt Lewin’s behavior equation, his simple model of human behavior, is excellent. It’s simplicity helps make it memorable, but belies a great insight into what affects how people behave.

The key premise that people are affected by both their internal factors (P) and the external factors around them (E) seems, like many great ideas, totally obvious once you’re aware of it. And perhaps it is. Even so, it’s still excellent. Of course, the time we spend in the various environments we inhabit also shapes who we are as people (P), so the cycle of influence is complex.

Some of the key take-aways from this model are to do with the importance of shaping environments to affect behaviors. Designers and influences throughout the world do this, often with an aim of getting you to spend more money (e.g. placing cheap, sweet snacks near the check-outs in shops) though sometimes more benevolently (like designing buildings with lifts that are less obvious than their stairs).

There are lessons all of us as individuals can learn from Lewin’s Behavior Model in relation to designing our own environments. These lessons span our physical environment (where one of the best ways to make sure you eat healthily is to not buy unhealthy food) to our social environments where it’s been shown that our behaviors will “norm” to those adopted by the wider group. Hanging around with a lot of people who eat healthily and exercise, will probably mean you too exercise more and eat healthily.

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Lewin, Kurt, Fritz Heider, and Grace M. Heider. 1936. Principles of topological psychology. New York: McGraw-Hill Book Company, Inc.

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