Just noticeable difference (JND), also known as the difference threshold, is the minimum level of stimulation that a person can detect 50% of the time. For example, if you were asked to hold two objects of different weight, the difference you might feel right now would be the minimum weight difference between the two, which you might feel half the time. This is followed by everyday examples in which the currently noticeable difference can be observed. For example, imagine that you are in a dark cinema. The lighting in the house begins to turn on slowly and you immediately notice even a very small change in light intensity. Then leave the theater and go out where the sun shines. If the same changes in light intensity were made outdoors, you are less likely to notice them because the stimulus level is much higher. Imagine holding a paperback book in your hand. You can obviously feel the weight of the book as well as the overall size and shape.

If we were to put another pound of similar size, shape, and weight in the same hand, you could see the extra weight. If we were to put another book that is a little heavier or has a different shape in your other hand, you could decide which book is lighter or heavier. Both are an example of the threshold of difference. This is a theory that can be very useful. In fact, we probably struggle with this theory every day without really realizing it. Just like many theories in the vast field of psychology, people constantly prove or refute the correctness of theories. This law is no exception. Let`s look at some examples where Weber`s law is both present and useful.

For example, the absolute threshold of sound would be the lowest volume a person could perceive. The just noticeable difference would be the smallest change in volume a person could feel. You volunteer for another psychological experiment at your school. This time, the experimenters put small amounts of sugar in a container of water and ask you to drink it. You will be asked to say when you notice the softness of the water compared to the still water. The smallest level of sweetness you can taste half the time is the threshold of difference. In the simplest case, this theory concerns human perception. In particular, this theory seeks to understand how humans can perceive the slightest difference between two stimuli. This theory appeals to each of the five senses – touch, taste, smell, sight and hearing – and suggests that human perception is sharp enough to accurately distinguish the smallest differences. However, we encounter some challenges when confronted with light. The intensity of bright lights, such as the sun or a flashlight shining in our eyes, is so great that we may have difficulty detecting dimmer lights, colors, and even objects until our eyes adapt.

This is another way in which the intensity of the initial stimulus can undermine the threshold of difference. The human ear is a very sensitive thing. When we focus, we can really hear the smallest sounds of a room, which is why we can easily listen to a juicy conversation in a crowded room. However, if we overwhelm the threshold of difference with an intense primordial stimulus, subsequent stimuli will be more difficult to detect. That`s why people have trouble getting along during concerts. The sound of the concert is so loud that it is almost impossible to hear the person next to you, even if they yell in your face. The intensity of the stimulus may also play a role in how people notice changes. If a light is very, very dim, people may notice smaller changes in intensity rather than if the same changes were made to brighter light. Differential thresholds and other phenomena can help researchers understand how people react to their environment and where human senses are prone to error. Imagine volunteering for a psychological experiment at your school.

Researchers ask you to hold two small amounts of sand in each hand. An experimenter slowly adds small amounts of sand to one hand and asks you to tell when you notice that one hand feels heavier than the other. The smallest difference in weight you can notice at least half the time is the difference you notice. It is important to understand the currently noticeable difference from the absolute threshold. While the difference threshold or just noticeable difference between two stimuli means recognizing differences in stimulation levels, absolute threshold refers to the smallest level of detectable stimulation. Neuropsychologists are trying to understand how human perception is translated by the brain. One way to do this is to examine the brain by MRI and expose volunteers to various stimuli. Some of this research has allowed neurologists to safely isolate the parts of the brain responsible for sensory processing. Although not often talked about, Weber`s law is a cornerstone of neuropsychology. As one of the most enduring psychological theories in the field, this law and the legal principles associated with it continue to advocate the sensitivity of human perception.

In Weber`s theory of law, the „threshold of difference” is the smallest absolute difference between two similar stimuli. Some neuropsychologists call this a „single noticeable difference.” In both cases, the threshold of difference justifies the theory with the caveat that the human mind can better perceive the difference between two stimuli, depending on the proximity of the comparative stimuli to the original stimuli. Or in other words, we humans can distinguish changes in stimuli, even if two stimuli are very similar. The original proposal of this theory in 1834 was made on the basis of psychophysics, or the interface between psychology and physics. For this new theory, the easiest way to test it was to use something that could be easily measured and recorded: weight. Most people actually have a decent color perception because of the threshold of difference. If we placed two red cards in front of you and asked you which card is the most yellow, you could point to the red-orange card with some ease. If we placed two blue cards in front of you and asked you which card was the darkest, you could easily point to the darker card. If we placed two green cards in front of you and asked which one is more lively, you could choose the right card again.

The perception of human colors is usually right. JND is often studied in product development. For example, when making mobile phones, companies measure the JND of the volume, so there are noticeable increases when you increase the volume on your device. APA Dictionary of Psychology. Psychophysics. American Psychological Association. Reducing packaging saves companies money, but it`s often seen as an unethical practice – getting consumers to buy their favorite products at the same (or more) prices, but they get less of them without knowing it. You watch TV with your partner, but the volume is too low to hear them. You ask your partner to increase it. You press the volume button twice, but you still can`t tell the volume difference. Your partner presses the button twice more before you can notice the increase in volume. To measure sensory information and thresholds of difference, scientists rely on the responses of study participants.

The measurements made by scientists depend on the sensory information received.