The configural properties of task stimuli do influence vigilance performance.

Sixty-one participants performed a sustained attention task in which they were required to respond to a critical signal requiring feature discrimination. Three separate groups performed the task with different global display configurations. The local feature elements (directional arrow shapes) were displayed on either a circle, a circle broken apart or a reconnected figure. For two of the groups, the entire display consisted of a clear global shape (circle and reconnected), and for one of the groups, the display had no discernible global element (broken circle) despite the critical signal being the same for all the groups. Analyses of hit rate and A' scores indicated that the broken circle group had impaired performance compared to the global figure groups. A configural superiority effect was found in which performance was improved by having a global shape property to the entire display. These results provide a behavioural base for further research utilizing measures of cerebral activation, as cerebral activity during vigilance tasks may be dependent on both task difficulty and hierarchical aspects of the display. The configurable or hierarchical aspects of vigilance displays may be critical in understanding sustained attention performance and its hemispheric lateralization.