Hook Model

Biological Parallel

The hook model (trigger → action → variable reward → investment) mirrors the foraging loop: hunger signal → search → unpredictable food find → cache investment that creates future triggers. Squirrels demonstrate this perfectly: hunger triggers searching, variable nut finds create dopamine spikes, and cached nuts create both future investments and future triggers (the squirrel must return). Rats pressing levers for variable rewards will persist 10x longer than those receiving predictable rewards—the uncertainty itself is addictive. Scrub jays show investment escalation: they cache more valuable food items in harder-to-find locations, investing more effort to protect their best discoveries. Apps don't create addictive loops; they hijack ones that evolved to keep animals alive in uncertain environments.