What theory explains that the threshold for sensing a stimulus is influenced by both the stimulus and background stimulation?

Signal-detection theory is the concept that explains how the threshold for sensing a stimulus is affected not only by the characteristics of the stimulus itself but also by external factors such as background noise and the individual's psychological state. This theory posits that detection of a signal occurs amidst the presence of noise, and decisions about whether a signal is present are influenced by the person's experiences, expectations, and the context in which the stimulus is presented.

In essence, signal-detection theory highlights the importance of both sensitivity to the stimulus and the response criteria set by the individual, which can be affected by various factors including motivation, alertness, and the stakes of the decision being made. This makes the theory particularly useful in understanding how people perceive stimuli under varying conditions, as it accounts for both the physical aspects of the stimulus and the psychological influences at play.

The other theories mentioned, such as Weber's law, focus on the relationship between the intensity of a stimulus and the smallest detectable difference (just noticeable difference), while opponent-process theory relates to how color perception is processed in opposing pairs. Dual-process theory addresses different cognitive processes rather than specifically the thresholds for sensing stimuli against background stimulation.