This research sought to explain online searchers' stopping behaviors when interacting with search engine result pages (SERPs) using the theories of Information Scent and Need for Cognition (NFC). Specifically, the problems addressed were how: (1) information scent level, operationalized as the number of relevant documents on the first SERP, (2) information scent pattern, operationalized as the distribution of relevant and non-relevant results on the first SERP, and (3) NFC, a person's tendency to engage in and enjoy effortful cognitive activities measured by the Need for Cognition scale, impacted a person's search stopping behaviors. The two search stopping behaviors that were examined were query stopping, or the point at which a person decides to issue a new query, and task stopping, or the point at which a person decides to end the search task. A laboratory experiment was conducted with 48 participants, who were asked to gather information for six open-ended search tasks. Participants were interviewed about their search stopping behaviors at the end of the study using recordings of their search processes to stimulate recall. The results showed significant effects of Information Scent and NFC on search stopping behaviors. When there were more relevant results on the first SERP, participants examined more documents and explored deeper in the search results list. Participants' behaviors were also affected by the distribution of relevant results on the first SERP: when relevant results were found at the top of the SERP, participants left the SERP after viewing only the first few results. When participants encountered relevant results dispersed across the first SERP at the start of a search task, participants issued more queries subsequently to solve the search task. Participants with lower NFC searched deeper but reformulated queries less frequently during a task. Moreover, the time participants with lower NFC spent evaluating search results was more variable depending on the number of relevant results displayed on the first SERP than the time spent by higher NFC participants. Finally, participants reported that they tended to examine results beyond the first SERP when they conducted people, product, image and literature searches in daily life.