Are event-splitting effects actually boundary effects?

An event-splitting effect (ESE) occurs when an event, which yields a positi ve outcome in one lottery but zero under another, is separated into two sub -events and this increases the relative attractiveness of the former lotter y. ESEs are attributed to either (1) a preference for more positive outcome s in lotteries, or (2) an aversion to more zero outcomes. An experiment is reported which replicates ESEs whilst controlling for explanation (2). This favours explanation (1), but a lack of generality in replication suggests previous ESEs to be partially due to (2). Implications are discussed for a related choice phenomena, decision theory, and real-world decision-making.