The effects of array structure and secondary cognitive task demand on processes of visual search

Many aspects of our everyday behaviour require that we search for objects. However, in real situations search is often conducted while internal and external factors compete for our attention resources. Cognitive distraction interferes with our ability to search for targets, increasing search times. Here we consider whether effects of cognitive distraction interfere differentially with three distinct phases of search: initiating search, overtly scanning through items in the display, and verifying that the object is indeed the target of search once it has been fixated. Furthermore, we consider whether strategic components of visual search that emerge when searching items organized into structured arrays are susceptible to cognitive distraction or not. We used Gilchrist & Harvey's (2006) structured and unstructured visual search paradigm with the addition of Savage, Potter & Tatler's (2013) secondary puzzle task. Cognitive load influenced two phases of search: 1) scanning times and 2) verification times. Under high load, fixation durations were longer and re-fixations of distracters were more common. In terms of scanning strategy, we replicated Gilchrist & Harvey's (2006) findings of more systematic search for structured arrays than unstructured ones. We also found an effect of cognitive load on this aspect of search but only in structured arrays. Our findings suggest that our eyes, by default, produce an autonomous scanning pattern that is modulated but not completely eliminated by secondary cognitive load.