Psychology MCAT Practice Exam

Which term describes the minimum difference between two stimuli to detect 50% of the time?

1. Absolute threshold

2. Differential threshold

3. Just Noticeable Difference

4. Sensory adaptation

The correct answer is: Just Noticeable Difference

The term that describes the minimum difference between two stimuli needed for detection 50% of the time is known as the Just Noticeable Difference (JND). This concept stems from the field of psychophysics, which studies the relationship between physical stimuli and the sensations and perceptions they produce. The JND signifies the smallest change in stimulus intensity that can be detected, making it essential in understanding perception. The concept is directly tied to the idea of difference thresholds, which gauge how sensitive a person's perception system is to changes in levels of stimuli. Essentially, if the change is smaller than the JND, it is less likely to be noticed, while if it is greater, it will typically be perceived as a difference. In contrast, the absolute threshold refers to the minimum level of stimulus intensity needed for perception at all, while the differential threshold relates to the concept of the smallest detectable difference, often used in conjunction with JND. Sensory adaptation describes the process by which sensitivity to stimulation diminishes over time, but it does not define a measurable difference in intensity. Thus, Just Noticeable Difference is the most accurate term for the situation described in the question.