Attention deployment towards a stimulus is strongly influenced by its associated value, shaped by past experiences and learning history. Earlier research found that distractors associated with higher rewards cause greater interference (slower response times and reduced accuracy) with finding a target in visual search tasks. This study aimed to uncover the neural mechanisms driving this value-based attention bias, focusing on three attentional sub-processes: enhancement of relevant information, attentional capture by irrelevant information, and suppression of irrelevant information.
We confirmed prior findings that high-reward distractors lead to more interference compared to low-reward distractors. Furthermore, a spatial gradient of interference was observed: performance dropped as distractors approached the target. The gradient was more pronounced for high-reward distractors.
Electrophysiological data from EEG provided insights into the mechanisms underlying this interference. High-reward distractors required stronger suppression, as shown by larger Pd components, particularly when these distractors were located near the target. This need for increased suppression reduced the resources available for target processing, evidenced by smaller target-N2pc amplitudes. Interestingly, the distractor-N2pc, a marker of attentional capture, was unaffected by either reward or proximity, suggesting that attentional capture alone does not explain interference caused by high-value stimuli.
In summary, our results show that the higher need for suppression of high-value stimuli contributes to reward-modulated attention deployment and increased suppression can prevent attentional capture of high-value stimuli.