摘要
過去研究顯示，後向對比遮蔽（metacontrast masking）是由於低層次視覺管道間的相互抑制而造成視覺目標受到在空間上未重疊且時間上延宕出現的遮蔽物影響而降低其可見性。本研究探討被遮蔽的視覺目標，其可見性是否會受到聲音訊息的出現而有所改變，並且探討聲音是如何影響對視覺訊息的判斷。實驗一藉由聲音呈現在相對於視覺目標出現的不同時間點，檢驗聲音對視覺目標可見性的影響。結果發現，當聲音出現在被遮蔽的視覺目標之前，會增加對視覺目標的敏感度（d’）。實驗二、三採用空間線索實驗典範，分別操弄聲音線索和視覺目標的空間一致性（實驗二），以及聲音線索和視覺目標兩者出現的時距（實驗三）。目的在於檢驗聲音線索的出現，是否會造成注意力移動至線索的位置及其時間窗。此外，亦採用視覺線索當作對照組，比較單一感官和跨感官的空間線索效果。結果發現，藉由定位注意力至線索出現的位置，聲音能夠有效增進視覺目標的可見性。在後向對比遮蔽實驗中，聲音或許是透過回饋路徑的調節，支撐視覺目標的物體表徵以增進吾人對視覺目標的敏感度。
並列摘要
In metacontrast masking (MM), reduced target visibility by a temporally lagging and spatially non-overlapping mask is attributed to inhibition between low-level visual channels. Here, we examine whether and how an auditory signal can enhance target visibility in MM. We first tested the effect of sound on MM by presenting a sound at different points in time with respect to the target and found enhanced perceptual sensitivity of the masked target when the sound was presented before the target (Experiment 1). Experiment 2 and 3 used a spatial cuing paradigm in which the spatial congruency of the sound and target (Experiment 2) and the cue-target-onset-asynchrony (Experiment 3) were manipulated to examine whether an auditory cue shifts attention to the cued location and its appropriate time window. An equivalent visual cue was also used for comparison between within- and cross-modal spatial cueing effects. Results showed that sound enhanced target visibility in MM by orienting attention to its location, probably through a feedback modulation to sustain object representation of the visual target.