Final answer:
The concept that a threshold for sensing a stimulus is influenced by both the stimulus properties and background stimulation is explained by signal-detection theory.
Step-by-step explanation:
The idea that the threshold for sensing a stimulus depends not only on the properties of the stimulus itself but also on the level of background stimulation and the characteristics of the perceiver is explained by signal-detection theory. Signal-detection theory allows for variations in perception under different circumstances, reflecting changes in sensory and decision-making systems. This might explain, for example, why a mother might wake up at her baby's murmur but not at other sounds, or why an air traffic controller needs to distinguish plane signals from other blips on a radar.