Core distinction and conditions
Sensation concerns detecting and transducing physical stimulation; perception concerns how sensory information is organized and interpreted. An absolute threshold concerns whether a stimulus is detected under specified conditions, commonly using a half-of-trials convention. A difference threshold concerns how much change is needed to detect a difference. These are different tasks. Neither should be treated as an unchanging number for every observer and setting. Attention and motivation can also influence what is reported, so a report of detection is interpreted within the task rather than treated as a context-free reading of physical intensity.
Worked example: preserve a stated proportion
In an idealized comparison, a change of one unit is just noticeable against a reference intensity of fifty units. Under a stated Weber constant-proportion assumption over the tested range, the threshold fraction is one divided by fifty. At a reference of one hundred fifty units, the predicted difference is three units. The calculation keeps a fraction constant rather than keeping the raw difference constant. This is a conditional model calculation, not a claim that the relationship holds for every intensity or modality. Name the range assumption before applying it and distinguish the reference value from the smaller change being detected.
Contrast adaptation with another kind of task
A steady background odor can be experienced less strongly after continued exposure even when its concentration stays constant. That pattern illustrates sensory adaptation. It is different from comparing two odor intensities to find a difference threshold, or from learning that one cue predicts an event while another does not. It also does not show that the physical stimulus has disappeared. For a careful answer, say what changed in the environment and what changed in experience or behavior. If the task instead manipulates where attention is directed, that information belongs in the interpretation rather than being silently replaced with an adaptation story.
Transfer check: classify before calculating
A tone is detected on about half of its presentations under fixed testing conditions. Is that an absolute-threshold criterion or a comparison of two audible intensities? It is the former. For a separate task, a just noticeable difference is three units at a reference of sixty; a constant-fraction assumption would predict six at a reference of one hundred twenty. Explain the calculation and one limit on generalizing it. Finally, a constant odor feels weaker over time: identify the adaptation pattern without claiming the concentration changed. Formal signal-detection calculations and full sensory-system coverage remain outside this foundation set.
Try it, then explain it.
Complete a short set without looking at the example. After each answer, explain which evidence or rule supports your decision and why the alternatives do not fit.
Sources & authorship
Original OpenExam explanations and examples. References support the concepts; they are not the source of copied questions. Independent educator review is pending.
OpenStax Psychology 2e, section 5-1