psychofysica

Psychofysica, also known as psychophysics, is a branch of psychology that investigates the quantitative relationship between physical stimuli and the sensations and perceptions they produce. The field aims to describe how properties such as stimulus intensity, duration, frequency, and spatial configuration influence detectability, discrimination, and perceived magnitude.

Historically, psychofysica emerged in the 19th century with contributions from Gustav Fechner and Ernst Heinrich Weber. Weber's law states that the just-noticeable difference between two stimuli is proportional to the original intensity. Fechner expanded these ideas into a mathematical relation between physical energy and perceived sensation, often summarized as a logarithmic scaling. Early experimental methods, including the method of limits, the method of constant stimuli, and the method of adjustment, established procedures for measuring sensory thresholds and psychophysical functions.

Today, psychofysica encompasses sensory domains such as vision, hearing, touch, taste, and proprioception. It relies on rigorous experimental designs and statistical models, including signal detection theory, to separate true perceptual sensitivity from response biases. Scaling techniques, such as magnitude estimation, quantify perceived intensity on constructed psychophysical scales and help describe the shape of perceptual functions.

Applications of psychofysica span basic research in perception to applied fields like human factors, product testing, and clinical assessment of sensory disorders. The discipline provides a framework for understanding how physical energy is transformed into subjective experience, informing both theoretical models of perception and practical design considerations.