A Heuristic Equation to Explain Behavior, Performance, and Solutions

Psychology teaches us how to understand ourselves and other people. This true statement disguises immense, perhaps infinite, complexity.

As complex as psychology is, you can learn and accomplish much by using even simple (valid) theories. In 1936, pioneering psychologist Kurt Lewin published psychology’s most basic yet powerful equation: B = f [P, E].

Distinctly different from other 20th-century theories that emphasized either nature or nurture, Lewin explained that behavior (B) is a function of–caused by–both the person (P) and their environment (E). This single theory clarified psychology’s big-picture territory, allowed flexibility for different details for different topics, and applied to many psychology subfields.

Lewin elaborated in-depth, but the framework alone holds profound implications. To start, both person (P) and environment (E) affect behavior (B). When analyzing your actions or performance, or those of others, your analysis is incomplete and probably misleading if you are not considering both sets of possible causes.

We don’t use normally use Lewin’s framework explicitly or consciously. Still, we do analyze, interpret, and explain behavior (B) as due to at least one personal (P) or situational/environmental (E) cause. It’s common to think that we do this accurately, but the process is replete with biases and errors (attribution theory describes these). Routinely, we oversimplify; after quickly landing on the "obvious" explanation, we assume it’s correct and stop considering other possibilities.

However, most behaviors and types of performance (work, school, sports, and so on) have multiple causes, some residing in P and others in E. Many possibilities are ignored or not even considered, resulting in misunderstandings and mistaken or incomplete action plans.

For more clarity, consider a few examples showing the need to fully assess the full range of possible causes–P and E–of performance and other types of behaviors.

School grades. You're a teacher who just finished grading exams. You can attribute any score, whether high or low, to the student's knowledge or effort level, the nature of the exam, or your actions as a teacher. The list of options is longer yet. But we settle for the first one or two that strike us and miss the lessons learnable with a more thorough and accurate analysis.

Take a moment to revisit this example from the perspective of the student. Whether you receive a high or a low grade, you can imagine how many things influenced your performance. A prime example is when students receive a low score and blame outside factors (the teacher, the exam, or other pressing responsibilities) without considering their personal contributions (overconfidence, lack of studying, not keeping up). Only a complete analysis can avoid mistaken conclusions and provide proper lessons learned.

Sports. In sports, personal variables include skill level, preparation, conditioning, knowledge of opponents, and strategies. Environmental variables include the opponent, venue, officials, onlookers, partners or teammates, and so on. You can get down on yourself after a loss, but you can also realize that other things contributed to your loss. After a win, you can be happy and not learn anything, or you can be thrilled but also make an extra effort to learn from mistakes and play even better next time.

Work. My field is organizational psychology and leadership, so I’ve spent most of my years studying how to manage performance—one’s own and others'—in work settings. Job performance is always a function of both personal and situational factors. If you short-change your P/E analysis, you will miss opportunities for improvement and things to praise and be proud of. And please note: It’s often appropriate and helpful to seek the other party’s perspectives before making consequential decisions.

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Assessing presidents. The job performance of U.S. presidents and other public officials, like everyone else’s, is caused by combinations of P and E factors. A prime example—a key predictor of how people choose whether to re-elect their presidents—is whether economic conditions are good or bad.

Current conditions may be due partly to the incumbent president. Assessing them on this basis does drive voting behavior, but voters’ beliefs can easily be mistaken. Most likely, current economic conditions are due partly to the incumbent (P) but mainly to E factors like global circumstances, Congress, and their predecessors’ decisions.

So, next time you’re wondering Why’d they do that, What was I thinking, or What should we do next, start with Lewin’s far-reaching equation. You’ll probably find the correct answer–actually, several good possibilities–that can tell you 1) the why’s of your own and others’ behaviors and performances, 2) what might occur again, and 3) what you and others can do about it when wanting to improve.