The objective of this research was to investigate neurophysiological mechanisms underlying the development of cognitive lock-in. Cognitive lock-in describes a situation in which a consumer has learned how to use a website, based on repeated interactions with it, with the consequence that more experience reduces the probability to switch to a competitor’s website. A major reason for the reduced switching probability is that interaction with an unfamiliar website typically implies high levels of cognitive load. Researchers conducted an experiment measuring cognitive load while consumers performed online purchasing tasks. Results show that participants visiting the same website multiple times have different cognitive load patterns than participants visiting different websites. The former group rapidly moved from controlled processing to automatic processing, which is metabolically less costly, leading to cognitive lock-in. Theoretical contributions and managerial implications are discussed.