Change magnitude does not guide attention in an object change detection task

Investigations of change detection consistently reveal an effect of change magnitude: changes involving more object parts are detected more easily than those involving fewer parts. Whether large changes improve detection by providing stronger preattentive signals to the change location is subject to debate. We report a cued object change detection experiment that tested this hypothesis while controlling for stimulus familiarity, semantic knowledge, and change type (addition versus deletion). We found strong magnitude effects regardless of whether trials were validly or invalidly cued. The size of the cueing effects, which were exhibited for all the change magnitudes examined, did not decrease with the number of parts changing. These findings provide little support for a preattentive guidance hypothesis and instead support the thesis that change detection requires attention.