The salience (also called saliency) of an item is its state or quality of standing out relative to other items. Saliency detection is considered to be a key attentional mechanism that aids learning and survival by enabling organisms to focus their limited neurocomputational resources on a small yet pertinent subset of the available sensory data. Saliency can arise from spatial, temporal, or spatiotemporal differences, such as a red dot surrounded by white dots, a flickering message indicator of an answering machine, or a red dot moving relative to a white background. While these examples focus on visual saliency, similar mechanisms operate in other sensory modalities - sounds, flavors, scents, etc., can all stand out and attract attention. When attention is deployed based on salient stimuli, it is considered to be bottom-up, memory-free, and reactive. In contrast, when attention is deployed based on prior knowledge and expectations, such as when looking ahead of moving objects or sideways before crossing streets, it is referred to as top-down, memory-guided, or anticipatory. Humans and other animals cannot pay attention to more than one or very few items simultaneously, so they are faced with the challenge of continuously integrating and prioritizing different bottom-up and top-down influences. These integrative mechanisms are poorly understood.

External links

• A review of research on visual saliency from a computational perspective

Neuroscience