The Effect of Interruption in Visual Search

Visual search is a search for a target among other objects (distractors). Previous research has already shown that subsequent searches are influenced by previously performed searches. For example, if two searches are performed in the same display one after the other, the target can be found faster in the second search if it was among the last inspected objects of the previous search. It has also been shown that, if a search is interrupted briefly, it can be resumed relatively quickly after this interruption. However, until now it is unclear whether and to what extent an interruption affects the search behaviour before the interruption or a subsequent search. In this project, 12 experiments will be carried out which aim to answer these questions by measuring the eye movements of the participants during the search tasks. The results from this project will lead to new insights into the extent to which visual search processes in practice (e.g. when searching for tumours in x-rays or for dangerous objects in flight luggage) are influenced by interruptions.

In our daily lives, we constantly search for objects-whether it's looking for keys before leaving the house, finding a favorite product in a store, spotting a friend in a crowd, or scanning information on a computer screen. Many of these visual searches get interrupted-for example by a distracting signal, another task, or even our own decision to stop searching. But how do these different interruptions affect the search process? By systematically reviewing previous research, we found that interruptions often increase the further search time and increase the likelihood of missing the target. However, participants in those studies were typically interrupted when performing a single search and were also allowed to resume their search after that interruption. In a series of experiments, we were able to show that not only the interrupted search itself, but also a subsequent search in the same search environment is negatively affected: The time required for the next search is increased and more objects are fixated than if the previous search was not interrupted. In other experiments we found that people under time pressure almost always prioritized the first of two consecutive different searches, even if this reduced their chance of success for the second search. However, eye-tracking data also showed that participants adjusted their strategy for the second search, making smaller eye movements but spending more time fixating on objects. Finally, whereas most previous studies on interruptions in visual search have been conducted in controlled laboratory settings, we also investigated the impact of different interruptions on search performance and memory in real-world settings. Listening to a podcast or working under mild time pressure had little impact on search accuracy or speed. However, when participants had to actively remember a number while searching, their search accuracy decreased significantly, and they recalled fewer search items afterwards. Together, these findings have important implications beyond everyday life. For example, radiologists analyzing medical scans or air traffic controllers monitoring multiple screens frequently experience interruptions. Identifying which types of interruptions are most disruptive could help to design better systems that minimize their negative effects. Not all interruptions are equally harmful and by understanding their specific impacts, we can develop strategies and tools to support people during critical searches.