What is the smallest amount of stimulus that a person can reliably detect called?

The smallest amount of stimulus that a person can reliably detect is known as the absolute threshold. This concept is fundamental in the field of sensation and perception as it defines the minimum intensity of a stimulus that an individual can recognize at least 50% of the time. It serves as a baseline for understanding how sensory systems respond to various stimuli, such as light, sound, taste, touch, or smell.

The absolute threshold varies between individuals and can be influenced by numerous factors including age, health, and individual sensitivities. It is a critical concept for assessing sensory capabilities and is often determined through rigorous experimental methods where stimuli are presented at varying intensities until the participant can just barely perceive them.

Understanding the absolute threshold helps in distinguishing it from related concepts like the difference threshold, which refers to the minimum difference in stimulation that a person can detect 50% of the time, and just-noticeable difference, which is a specific measure of how much a stimulus must change to notice a difference. Constant threshold is not a standard term used in sensory psychology, which further clarifies the precise nature of what the absolute threshold represents in the context of reliable stimulus detection.