Are Abrupt Onsets Highly Salient?

Abrupt onsets are commonly assumed to be a class of stimuli with high physical salience. Presumably because of this, abrupt onsets tend to capture attention even when other types of distractors, such as color singletons, do not. However, there has been a lack of consensus on the definition and measurement of physical salience. As a result, it is unclear if high physical salience is indeed the reason why abrupt onsets tend to capture attention more strongly than other types of stimuli. Using a psychophysical technique recently developed by Stilwell et al. (2023), we explicitly quantified the level of physical salience of abrupt onsets, color singletons, and color singleton onsets. Surprisingly, abrupt onsets were the least salient among the three types of items. Despite this, only abrupt onsets captured attention in a subsequent visual search task, whereas the other two types of distractors were suppressed. These results indicate that high physical salience is neither a necessary nor a sufficient condition for abrupt onsets to capture attention.