Working memory has a limit
According to John Sweller's cognitive load theory (1988), working memory can only process a limited number of elements at once, and a poorly structured task wastes part of it. A complex project you keep "in your head" forces you to hold the end goal, the chain of dependencies and the state of progress all at once. This is not direct evidence about project management, but the mechanism fits what many teams observe: when everything lives in people's heads, mistakes and procrastination go up.
What breaking down really changes
Breaking a project into manageable sub-tasks (the idea behind the Work Breakdown Structure, see planning a project) brings at least three things, backed by research.
- A clearer sense of competence. Albert Bandura (1977) shows that confidence in one's ability to succeed at a task influences the effort made and persistence. "Build an app" is vague; "design the login form" has a size you can picture.
- More precise goals, hence more effective ones. Locke and Latham (2002) sum up thirty-five years of work: specific, challenging goals go with better performance than vague ones. A broken-down task has an identifiable finish criterion.
- An action plan that calms things down. Masicampo and Baumeister (2011) showed that a precise plan (when, where, how) is enough to reduce the mental grip of an unfinished goal, without having to complete it. Gollwitzer (1999) showed for his part that a simple "if this situation, then that action" plan clearly increases the likelihood of following through. We detail the first result in the article on the Zeigarnik effect, which also adds a caveat.
Why a visual board helps
A Kanban board, an Eisenhower matrix or a Gantt chart shift part of the mental work to the environment: the state of the project is visible, so you no longer reconstruct it from memory. Limiting tasks in progress also limits context switching (see the Kanban method). And shared visibility prevents one person alone from knowing the real state of the project.
In practice
A useful breakdown checks three things: each task has a result you can show, lasts less than a week, and has an owner. If a task does not meet these three conditions, there is probably something left to split.
Sources
- Sweller, J. (1988). Cognitive load during problem solving: Effects on learning. Cognitive Science, 12(2), 257-285. doi:10.1207/s15516709cog1202_4
- Bandura, A. (1977). Self-efficacy: Toward a unifying theory of behavioral change. Psychological Review, 84(2), 191-215. doi:10.1037/0033-295X.84.2.191
- Locke, E. A., & Latham, G. P. (2002). Building a practically useful theory of goal setting and task motivation: A 35-year odyssey. American Psychologist, 57(9), 705-717. doi:10.1037/0003-066X.57.9.705
- Masicampo, E. J., & Baumeister, R. F. (2011). Consider it done! Plan making can eliminate the cognitive effects of unfulfilled goals. Journal of Personality and Social Psychology, 101(4), 667-683. doi:10.1037/a0024192
- Gollwitzer, P. M. (1999). Implementation intentions: Strong effects of simple plans. American Psychologist, 54(7), 493-503. doi:10.1037/0003-066X.54.7.493