There must be a slight error. In the eyes of many students, the aunt in the canteen is like a random number generator-the same two meals, how much the aunt gives depends on the mood. But once a person is serious, his judgment by feeling can be very accurate. Some housewives can tell whether a vendor is short of a catty or two, and a good cook can taste whether there is a little more salt in the dish.

What determines the resolution of our perception of the world? In other words, to what extent can we accurately distinguish the difference between the two stimuli? How does this process work? About 200 years ago, scientists began to study this problem quantitatively and found the law. But until recently, we have just begun to understand the specific mechanism behind it.

Measuring perception for centuries, people have always thought that the spiritual world and the material world are completely different. Although the motion of inanimate objects can be measured by mathematical means, it is ultimately predictable; However, biological movement, or biological behavior, has long been considered to be dominated by will and driven by forces different from abiotic forces, and cannot be predicted in the same way.

Until 1834, Ernst Heinrich Weber, a German doctor, did a simple but ingenious experiment, which completely changed this situation. Weber asked the subjects to report which of the two objects with small weight difference they thought was heavier. In these experiments, he found that the probability of an individual making the right choice depends only on the ratio of weights.

Ernst Heinrich Weber. Weber has 1 1 brothers and sisters. Friends with a background in physics must know one of them-wilhelm eduard weber, and the magnetic flux unit is named after him. Image source: Wikipedia, for example, if the correct rate is 75% when comparing the weights of 1 kg and 1. 1 kg, then the correct rate is 75% when comparing the weights of 2 kg and 2.2 kg. In other words, when the weight of one object is 1. 1 times the weight of another object, the correct recognition rate of individuals is 75%.

This simple and clear rule opens the door to quantify human behavior with mathematical laws, and then it is applied to all sensory patterns of many species, which is the famous Weber's law. Later, Weber's student Gustav Fechner described this law mathematically, so it is also called Weber-Fechner Law.

The research of Weber and Fechner laid a solid foundation for the birth of psychophysics. This subject relates physical stimuli with psychological feelings in the individual's mind, describes clear perceptual rules, and can make mathematical explanations for human behavior controlled by brain processes.

Decoding Weber's law However, Weber's law, which pioneered psychophysics, soon became a major problem in this discipline. Over the years, researchers have proposed dozens of models to try to explain Weber's law. Although all of them can explain the results of Weber's experiment, no experiment can verify and find out the correct model.

For example, an influential model is signal detection theory. According to the signal detection theory, people's detection of signals depends not only on their own perception ability, but also on their own response standards. When two people have the same hearing sensitivity, if a person expects the appearance of a certain sound signal, then he may make more judgments on "signal appearance".

However, theory is theory after all, and there are still many such theories in this field waiting to be tested by experiments. Why is it so difficult to find the right model? A recent study found that academic circles may have overlooked a key variable, that is, decision-making time.