This paper explores synergies between the Behavioural OR (BOR) research stream and behavioural studies in the Information Systems discipline. Traditional models of the economics of search suggest that as information acquisition costs associated with searching for products and services online are greatly reduced because of the Internet, consumers should search more extensively in online contexts. Recent empirical research strongly contradicts this hypothesis. We provide an alternate explanation by situating the problem of limited search within an economy of attention. Informed by a behavioural decision theoretic approach, we develop an empirical framework for consumer attention based on the size of the consideration set, market concentration of attention and search time. We conduct a natural experiment using a commercial panel of online clickstream data from seven major consumer markets representative of search activity from one-million consumers. Our results show that a parsimonious consumer search process can be explained by accounting for the attentional limitations of online searchers. Consumers face an attention allocation problem characterised by a trade-off between the number of alternatives searched for and the time spent searching for information on individual alternatives. Furthermore, we find that the competitive context of online markets affects both the magnitude and strength of this relationship. We discuss practical and managerial implications of our findings.