Fluency heuristic

Biological Parallel

Processing fluency—ease of recognition—signals familiarity across independent lineages. Insects detect single pheromone molecules in 200-450 milliseconds, treating instant recognition as proof of nestmate. Zebrafish require a 24-hour imprinting window at 6 days post-fertilization to learn kin odor; miss it and they never acquire kin recognition. Pit vipers detect <0.001°C thermal differentials and strike prey at 99% accuracy in complete darkness—thermal fluency equals 'food.' Sheep achieve 99.43% facial recognition accuracy in 3.6 milliseconds, distinguishing familiar handlers from strangers. Plants respond to herbivore-induced volatiles from wounded neighbors in 5-10 minutes, activating defense priming—chemical fluency signals imminent threat. But fluency creates exploitable vulnerabilities: cuckoos evolved egg mimicry that hijacks reed warbler visual templates, causing hosts to occasionally reject their own eggs.