Foveal load and peripheral task performance: tunnel vision or general interference?
Abstract In scanning the visual field, the peripheral visual system selects objects of sufficient interest for the foveal system to analyse in more detail. Peripheral selection and foveal inspection are generally assumed to be performed simultaneously. A general finding is that peripheral performance deteriorates with increasing complexity of the foveal task. However, the nature of the decrease of peripheral task performance is still a matter of debate. Some studies suggest that a higher foveal load results in a larger decrease of peripheral task performance with increasing eccentricity (tunnel vision), whereas other studies report a uniform performance decrease over all eccentricities (general interference). The research question in this chapter is: does a cognitive load manipulation of a primary foveal task (memory comparison) result in tunnel vision or in general interference on a peripheral identification task? The Schneider and Shiffrin (1977) single-frame search task with varied mapping was used as the foveal task. There were two levels of cognitive load: a memory set size of one or two. The peripheral task was the identification of an arrow, pointing up or down, projected at a random position in the perimeter (eccentricities from 3.6 to 68°). Reaction times and errors were recorded. Peripheral reaction times showed a general interference effect: a higher foveal cognitive load resulted in a uniform decrease of peripheral task performance over all eccentricities.