Self-checkouts (SCOs) have become an integral part of many retail servicescapes. While SCOs have the potential to improve service while simultaneously cutting operations costs, achieving satisfactory utilization rates for them can be challenging. As these systems come with high investment costs, it is important for managers to understand how customers choose between traditional service and self-service technology. To understand this choice better, we study the cognitive processes consumers use in their decision-making through the lens of dual-systems theories. We conduct an exploratory field study where we observe and interview customers checking out from retail stores. We discover four distinct customer types regarding the extent of reflexive (automatic) and reflective (deliberate) processing they use in their checkout selection: habitual traditional checkout users, habitual SCO users, situational users, and drifting users. Moreover, we find that the processing styles are highly related to the different stages of technology acceptance.