Abstract: Previous research has documented that contour detection may be affected by local features such as element spacing and by high-level cognitive factors such as attention in our visual system. However, less is known about how high and low level factors interact to influence contour integration in the brain. In this paper, we aim to investigate how attention modulates contour integration through saliency (different element spacing) and topological properties (circle- or S- shaped). Perceptual load is known to tune attention and is tightly entangled with conscious awareness. We manipulated perceptual load by changing the difficulty of an initial memorization task for a foveal go/no-go task to investigate the processing level of contours in a modified inattentional blindness (IB) paradigm. The Posner cuing effect was utilized to assess with different contours as the spatial cue. A three-phase procedure was used to manipulate conscious awareness (conscious or unconscious) with a temporal two-alternative forced-choice (2AFC) contour detection task. The results showed that, 1) circles and S-contours induced different Posner cuing effects with low perceptual load while neither type could induce the effect with high perceptual load; 2) saliency was a predominant feature for contour detection and integration with minimal influence of perception load as no Posner cuing effect was found for non-salient contours with or without conscious awareness, whether they were closed or open; and 3) conscious awareness played a pivotal role in coordinating a closure effect based on the level of perception load. It was with low perceptual load that the closure effect was found in the unconscious condition rather than in the conscious condition. Our findings provide further evidence for contour detection and integration with a bi-directional mechanism in which low-level sensory factors interact with high-level cognitive factors. Future work is needed to explore the neural underpinnings of the mechanism.