1. Sensitivity
Sensitivity is the ability of sensory organs to perceive appropriate stimuli. Sensitivity is represented by the sensory threshold, and there is an inverse relationship between sensitivity and sensory threshold.
2. Absolute Sensory Threshold
The absolute sensory threshold is the minimum stimulus intensity that can evoke sensation. The absolute sensory threshold represents absolute sensitivity.
3. Difference Sensory Threshold
The difference sensory threshold is the minimum amount of change in a stimulus that can just evoke a difference sensation. It is also called the difference threshold or the just noticeable difference (JND). The difference sensory threshold represents difference sensitivity.
4. Weber's Law
Weber discovered that the difference threshold changes with the variation of the original stimulus intensity, but the ratio of the difference threshold to the original stimulus intensity remains constant. Formula: K=△I/I (K is a constant, △I is the difference threshold, I is the stimulus intensity). Weber's law only applies to stimuli of moderate intensity.
5. Fechner's Law
Inspired by Weber's law, Fechner conducted experiments to measure the relationship between stimulus intensity and the perceived magnitude of sensation. He found that the intensity of sensation is proportional to the logarithm of stimulus intensity. Formula: P=Klog(I) (P is the psychological quantity of sensation, I is the physical quantity of stimulus, K is a correction value or constant). Fechner's research pioneered the field of psychophysics. Fechner's law assumes that all just noticeable differences are subjectively equal and is based on Weber's law, so it also only applies to stimuli of moderate intensity.
6. Stevens' Power Law
Stevens discovered that the psychological quantity is proportional to the power of the physical quantity of the stimulus. It is also known as the power law. Formula: P=KIn (P is the psychological quantity, I is the physical quantity of the stimulus, K and n are constants).