Final answer:
The smallest amount of a stimulus that a person can reliably detect is called the absolute threshold. It refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time.
Step-by-step explanation:
The smallest amount of a stimulus that a person can reliably detect is called the absolute threshold. It refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time.
For example, imagine you are in a dark movie theater and someone's cell phone screen lights up. Most people would notice the change in illumination because it is above the absolute threshold. However, if the same thing happened in a brightly lit arena during a basketball game, very few people would notice because the change is below the absolute threshold.
Absolute thresholds are generally measured under optimal conditions for sensitivity and can vary depending on the sensory system and the specific stimulus.