Feature-based attention enhances the binding between fine-grained features and responses.

Evidence suggested that stimulus-response bindings could occur automatically as a result of the co-occurrence of a stimulus and a response, without requiring additional attentional involvement for features or objects. Considering that stimuli used in previous research often involved high-discriminability features processed automatically, the current study investigated the role of feature types in attention-modulated stimulus-response binding. Using the classic partial repetition cost (PRC) paradigm, the study manipulated the task relevance of features during the binding phase to modulate feature-based attention, with color and Landolt-C gap orientation as experimental features. The study found that when the stimulus feature was color (a high-discriminability feature), no significant difference was observed in the PRC effect during the retrieval phase, regardless of whether attention was directed to the color during the binding phase. When the stimulus feature was the gap orientation of the Landolt-C (a fine-grained feature), the PRC effect appeared during the retrieval phase, regardless of attention to gap orientation during the binding phase. However, the PRC effect was stronger when attention was directed to gap orientation, indicating that feature-based attention during the binding phase enhanced the binding strength between the gap orientation of the Landolt-C and the response. This study suggests that stimulus-response binding occurs automatically, but its binding strength is modulated by attention, with the type of stimulus feature playing a critical role in this process. Stimulus-driven and goal-driven factors jointly influence the strength of stimulus-response binding.