stimulusintensitet

Stimulusintensitet, or stimulus intensity, denotes the strength of a physical stimulus as it is detected by a sensory system. It is a central parameter in psychophysics and physiology and applies across modalities such as vision, audition, touch, taste, and olfaction. Intensity can refer to various physical quantities depending on the modality: luminance or irradiance for vision, sound pressure level for hearing, mechanical force or pressure for touch, concentration for chemical senses.

Perceived intensity generally grows with physical intensity but not linearly. The relationship is described by laws such as Weber-Fechner, which posits a logarithmic relation between stimulus magnitude and perceived magnitude, and Stevens' power law, which uses modality-specific exponents. Measurements use physical units (candela/m2, decibels, pascals, newtons) and psychophysical tasks to determine thresholds, such as absolute threshold (minimum detectable intensity) and differential threshold or JND (the smallest detectable difference). Instruments and calibrations ensure accurate control of intensity across trials, with attention to adaptation and context.

Understanding stimulus intensity informs sensory design, ergonomics, and safety, as well as research into receptor dynamics and neural coding. In experiments, stimuli are often varied across a defined range to characterize response functions, determine dynamic range, saturation, and detectability. Across modalities, the same basic concept—how strong a stimulus is and how that strength maps to perception—guides interpretation of data and modeling of sensory systems.