Abstract
An unexpected novel (surprise) feature is said to capture attention and gaze later than contingent capture by a target-defining feature, or singleton capture by a single salient item. Different tasks, however, may bias estimates of latency. For instance, contingent capture has been examined in a spatial cueing task, where the cueing display precedes the target display such that the cue is presented with little competition for attention from other stimuli. In contrast, surprise capture has mainly been examined in a visual search task, where the surprise feature competes with task-defined target candidates. In addition, latency estimates may concern the earliest or the average latency of an effect. One conclusion is that latencies have to be compared within the same experimental paradigm, using the same definition of latency. Here, we use a spatial cuing task to compare the effect of an unexpected novel feature to the effect of an unexpected target-defining feature on eye movements. In a series of experiments, we find that gaze is strongly and quickly captured by both cue variants, with little differences between them. This result is interpreted in a priority map framework, where attentional allocation depends on the competition between surprise-related and task-related signals. This account also implies that estimates of latency are specific to the task in which the measurements are made, because the task influences the amount of competition within a display. Further discussion concerns the role of different variables and criteria for latency estimates.
Acknowledgement: The work was supported by the Cluster of Excellence – Cognitive Interaction Technology ‘CITEC’ (EXC 277) at Bielefeld University, which is funded by the German Research Foundation (DFG), and by DFG grant HO 3248/2-1 to Gernot Horstmann.