© 2020 Elsevier LtdThe question of whether consumer purchasing decisions are conscious choices or unconscious has long been studied in marketing. The ability to measure mental changes with high temporal resolution makes the EEG-based event-related potentials (ERP) method very useful in studying the distinction between consciousness and unconsciousness. Although experiences with brands significantly affect the awareness or unconsciousness of decisions to purchase, ERP studies have ignored experiences of consumers in relation to brand purchases. For this purpose, EEG recordings of participants were taken in the order they saw brand names: experienced brands, review-based brands, and unknown brands. Participants chose one of the three options for the brands they saw on the screen: buying, not buying, and no idea. 35 people participated in the study. The results indicate that early ERPs, which are unconscious mental reactions, related to purchase decisions for previously unknown brands. Late ERPs associated with conscious mental reactions are related to purchasing review-based brands or experienced brands. We conclude that purchasing decisions about unknown brands occur as a result of automatic, unconscious mental processes, whereas purchasing decisions about previously experienced brands and based on consumer reviews result from conscious mental processes. Our study is the first that demonstrates the relationship between ERP's and purchasing decisions, with an experimental design focused on consumer experience and consciousness.