Saliency

Saliency refers to the quality of a stimulus or location that makes it stand out relative to its surroundings and thereby attract attention. In psychology and neuroscience, saliency describes mechanisms that bias perception toward conspicuous elements in the environment, which can arise from basic feature differences or from more complex contextual factors.

Saliency can arise from bottom-up or top-down processes. Bottom-up saliency is driven by the inherent properties of the stimulus, such as brightness, color, contrast, motion, or novelty, and is largely automatic. Top-down saliency reflects task goals, expectations, and prior knowledge, shaping what is considered important in a given situation. Together, these influences guide where observers look and what they perceive first.

In vision research, saliency is often modeled with saliency maps that assign a value to locations in an image, indicating their likely attention-capturing power. Classical models emphasized simple feature contrasts, while modern approaches increasingly use data-driven methods, including deep learning, to account for complex scenes and contextual effects.

Neural correlates of saliency involve networks in the cerebral cortex and subcortical structures, including parietal regions and frontal eye fields, which coordinate attention and eye movements. Saliency concepts extend beyond vision to other senses and to multisensory contexts, marketing, user interface design, and robotics, where predicting or shaping attention can be advantageous.

Limitations include that saliency is probabilistic, not deterministic; strong top-down goals can override salient stimuli; and context can modulate what is considered salient in a given situation.