Attentional suppression of dynamic versus static salient distractors.

Attention must be carefully controlled to avoid distraction by salient stimuli. The signal suppression hypothesis proposes that salient stimuli can be proactively suppressed to prevent distraction. Although this hypothesis has garnered much support, most previous studies have used one class of salient distractors: color singletons. It therefore remains unclear whether other kinds of salient distractors can also be suppressed. The current study directly compared suppression of a variety of salient stimuli using an attentional capture task that was adapted for eye tracking. The working hypothesis was that static salient stimuli (e.g., color singletons) would be easier to suppress than dynamic salient stimuli (e.g., motion singletons). The results showed that participants could ignore a wide variety of salient distractors. Importantly, suppression was weaker and slower to develop for dynamic salient stimuli than static salient stimuli. A final experiment revealed that adding a static salient feature to a dynamic motion distractor greatly improved suppression. Altogether, the results suggest that an underlying inhibitory process is applied to all kinds of salient distractors, but that suppression is more readily applied to static features than dynamic features.

The role of salience in the suppression of distracting stimuli.

Researchers have long debated whether salient distractors have the power to automatically capture attention. Recent research has suggested a potential resolution, called the signal suppression hypothesis, whereby salient distractors produce a bottom-up salience signal, but can be suppressed to prevent visual distraction. This account, however, has been criticized on the grounds that previous studies may have used distractors that were only weakly salient. This claim has been difficult to empirically test because there are currently no well-established measures of salience. The current study addresses this by introducing a psychophysical technique to measure salience. First, we generated displays that aimed to manipulate the salience of two color singletons via color contrast. We then verified that this manipulation was successful using a psychophysical technique to determine the minimum exposure duration required to detect each color singleton. The key finding was that high-contrast singletons were detected at briefer exposure thresholds than low-contrast singletons, suggesting that high-contrast singletons were more salient. Next, we evaluated the participants' ability to ignore these singletons in a task in which they were task irrelevant. The results showed that, if anything, high-salience singletons were more strongly suppressed than low-salience singletons. These results generally support the signal suppression hypothesis and refute claims that highly salient singletons cannot be ignored.

Oculomotor suppression of abrupt onsets versus color singletons.

There is considerable evidence that salient items can be suppressed in order to prevent attentional capture. However, this evidence has relied almost exclusively on paradigms using color singletons as salient distractors. It is therefore unclear whether other kinds of salient stimuli, such as abrupt onsets, can also be suppressed. Using an additional singleton paradigm optimized for detecting oculomotor suppression, we directly compared color singletons with abrupt onsets. Participants searched for a target shape (e.g., green diamond) and attempted to ignore salient distractors that were either abrupt onsets or color singletons. First eye movements were used to assess whether salient distractors captured attention or were instead suppressed. Initial experiments using a type of abrupt onset from classic attentional capture studies (four white dots) revealed that abrupt onsets strongly captured attention whereas color singletons were suppressed. After controlling for important differences between the onsets and color singletons - such as luminance and color - abrupt-onset capture was reduced but not eliminated. We ultimately conclude that abrupt onsets are not suppressed like color singletons.

Introspective awareness of oculomotor attentional capture.

Recent research has demonstrated that observers can learn to prevent attentional capture by physically salient stimuli. One critical question is how observers learn to avoid capture, particularly in situations where they receive no direct feedback about attentional performance. One possibility is that individuals have some level of introspective awareness of capture when it occurs. Once capture is detected, participants then adjust performance strategies to avoid subsequent attentional capture. It is currently unclear, however, if observers have any introspective awareness of attentional capture when it occurs. In the current study, participants attempted to locate a target shape and ignore a salient distractor. On half of trials, participants were then asked to classify whether their first eye movement was misdirected to the singleton distractor on that trial. The results demonstrated that participants clearly had some level of introspective awareness of attentional capture: Oculomotor capture effects were much larger on "capture" report trials than on "no capture" report trials. Interestingly, there was no evidence that awareness of oculomotor capture prevented subsequent capture by salient items. Future research is needed to definitively determine whether metacognitive awareness can be used as a training tool to prevent capture. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Assessing introspective awareness of attention capture.

Visual attention can sometimes be involuntarily captured by salient stimuli, and this may lead to impaired performance in a variety of real-world tasks. If observers were aware that their attention was being captured, they might be able to exert control and avoid subsequent distraction. However, it is unknown whether observers can detect attention capture when it occurs. In the current study, participants searched for a target shape and attempted to ignore a salient color distractor. On a subset of trials, participants then immediately classified whether the salient distractor captured their attention ("capture" vs. "no capture"). Participants were slower and less accurate at detecting the target on trials on which they reported "capture" than "no capture." Follow-up experiments revealed that participants specifically detected covert shifts of attention to the salient item. Altogether, these results indicate that observers can have immediate awareness of visual distraction, at least under certain circumstances.