Task modulation of visual category selectivity at physical and conceptual levels: An ERP study

Visual perception emerges from dynamic interactions between bottom‑up sensory input and top‑down, task‑driven expectations. This study tested whether task‑related ERP modulations during object categorization depend on low‑level category‑specific features—specifically the amplitude spectrum (AS)—or if they arise later, independent of these features. Participants viewed grayscale images of animals and vehicles with either intact or equalized AS, each paired with an “X” or “O.” They performed either a category‑relevant task (animal vs. vehicle) or a category‑irrelevant task (“X” vs. “O”). Task demands influenced visual processing at multiple stages: task‑dependent category selectivity emerged early (70–90 ms) for images with intact AS information, and again at later stages (~180 ms onward) regardless of physical image characteristics. Crucially, early category selectivity driven by physical features did not persist into subsequent ERP components, indicating that evidence accumulation is not strictly cumulative across stages. These findings indicate that task demands shape both low‑level and higher‑level stages of visual processing, highlighting flexible interactions between physical stimulus properties and cognitive goals.