perception

Perception is the mental process of organizing, interpreting, and giving meaning to sensory input. It enables people to recognize objects, events, and scenes and to act appropriately. Perception differs from sensation, which is the detection of physical stimuli. While sensation provides raw data, perception constructs a useful representation of the world by integrating input with prior knowledge, expectations, attention, and context.

The perceptual system includes multiple modalities: vision, hearing, touch, taste, smell, proprioception, and vestibular sense. Visual perception is often described as a two-stage process: bottom-up processing of sensory data from the eyes and top-down interpretation based on memory and knowledge, aided by Gestalt principles that organize input into patterns. The brain combines information from different senses in multisensory integration to produce coherent experiences.

Perception is shaped by attention, learning, culture, and expectations, leading to variability and errors such as optical illusions. Perceptual constancies allow stable perception despite changes in illumination, distance, or angle. Neural substrates are distributed; the visual stream includes dorsal pathways for spatial processing and ventral pathways for object recognition, with higher-order areas integrating context and memory.

Developmentally, perception emerges in infancy and improves with experience. Disruptions can produce perceptual disorders, such as agnosias, neglect, or prosopagnosia, or auditory processing disorders. Researchers study perception with psychophysics and signal-detection theory to quantify sensitivity and decision criteria. Understanding perception informs fields from design and education to human-computer interaction and clinical assessment.