The relationship between inhibition of return and memory

When we search for a 5-cent coin in our purse or for a friend in a crowd we perform a very common behaviour: visual search. Visual search is defined as the search for a target object (e.g. the 5-cent coin) among all other non-target objects (e.g. all other coins in the purse). It is a behaviour that we show hundreds of times during a day most of the time without being aware of it. In the proposed grant we will investigate the relationship between two factors that have been shown to be essential in order to search efficiently. One of these factors is our memory. It ensures that we can remember at which places we have already looked and at which not. The other factor is called inhibition of return (IOR). Due to IOR we are hindered to immediately look back to those objects that we have just inspected. Such inhibition ensures that we search at new places where we have not looked yet and thus find the target faster. One might assume that this IOR is somehow also a sort of memory: In order to inhibit looking back to previous objects it is necessary to know or remember which objects were checked previously. Surprisingly, research so far does not provide any hint whether IOR and memory are more or less the same or whether both factors work separately. With the proposed grant we intend to answer this important question. In a series of experiments we will investigate the relationship between IOR and memory by measuring the eye movements of our participants while they are performing visual search tasks. Our aim is to provide a better understanding of these two key factors in visual search. This will have a substantial impact on future research in this area.

When we search for a 5-cent coin in our purse or for a friend in a crowd, we perform a very common behaviour: visual search. Visual search is defined as the search for a target object (e.g. the 5-cent coin) among all other non-target objects (e.g. all other coins in the purse) and one of the most important tasks for investigating attentional processes. In the project, we investigated the relationship between two factors that have been shown to be essential to search efficiently: Memory and Inhibition of return (IOR). Memory ensures that we can remember at which places we have already looked and at which not while IOR hinders us to immediately look back to the objects that we have just inspected. Such inhibition ensures that we search at "new" places where we have not looked yet and thus find the target faster. One might assume that this IOR is somehow also a sort of memory: In order to inhibit looking back to previous objects, it is necessary "to know" or remember which objects were already inspected. Furthermore, items that are irrelevant for a subsequent task should be inhibited more than prospectively relevant items. In the project, we conducted several eye tracking experiments regarding these questions. We could show that IOR was present during a search but not necessarily persisted once the search was completed while the finding regarding the influence of short-term memory remained less clear. With regard to the question of whether IOR is affected by the (prospective) relevance of an object, our results suggest that, although IOR per se is not affected by a certain object's relevance, the oculomotor search process is. Overall, the findings of the project provide a better understanding of the connection of (short-term) memory and IOR in visual search and are hence of interest for related areas of, e.g., clinical neurosciences and applied cognitive psychology.