Definition
The cumulative effect is what you see only after enough identical reps crossed a threshold — personality did not change in a day; the stack did.
Origin
Learning curves and habit literature — behaviour change often looks flat until a step-function improvement (or collapse). Same structure as compound interest: small inputs, delayed lag.
Mechanism
People quit during the flat phase because the lag has not moved. Lally et al. model habit automaticity as an asymptotic curve — time to plateau ranged from 18 to 254 days in their field study, and a single missed day did not reset the curve materially. Ericsson et al. tie visible expert performance to prolonged deliberate practice — with a modest contrasting literature on innate-talent explanations. The lead (weekly battle, voice rep, exposure rep) is the only honest control surface during the flat stretch.
Pair with Mithridatisation: mechanism is dose; cumulative effect is what the graph looks like six weeks later.
Applications
When someone says “nothing works,” plot rep count before debating identity. Celebrate micro-wins as stack evidence, not mood.
Sources
Cite
- Ericsson, K. A., Krampe, R. T., & Tesch-Römer, C. (1993). The role of deliberate practice in the acquisition of expert performance. Psychological Review, 100(3), 363–406.
- Lally, P., van Jaarsveld, C. H. M., Potts, H. W. W., & Wardle, J. (2010). How are habits formed: Modelling habit formation in…. European Journal of Social Psychology, 40(6), 998–1009