托福阅读真题+题目+答案：The Difference Threshold and Signal-detection Theory

托福阅读真题+题目+答案：The Difference Threshold and Signal-detection Theory

How much weight must be added to or subtracted from a stack of books for the carrier to sense that the load is heavier or lighter? The just-noticeable difference (JND) is the smallest change in sensation that a person is able to detect 50 percent of the time. The difference threshold is a measure of the smallest increase or decrease in a physical stimulus that is required to produce the JND. A person holding a 5-pound load would notice the addition of a single pound, but a person already holding 100 pounds would not be able to sense an additional pound. More than 150 years ago, researcher Ernst Weber(1795-1878)observed that the JND for all the senses depends on a proportion or percent of change rather than a fixed amount of change. This observation became known as Weber's law. A weight being held must increase or decrease by 2 percent for the difference to be noticed. According to Weber's law, the greater the original stimulus, the more it must be increased or decreased for the difference to be noticeable.

1.According to paragraph 1, Weber's law states which of the following?

A The difference threshold is not the same for all senses.

B The just-noticeable difference is the smallest change in sensation that is noticed half the time.

C People are more likely to notice a slight increase in sensation than a slight decrease in sensation.

D The stronger the original sensation, the more it must change for the difference to be noticeable.

2.According to paragraph 1, what would the difference threshold be for a person carrying a physical weight such as a load of books?

O One pound

O Five pounds

O 2 percent

O 10 percent

The difference threshold is not the same for all the senses. very large (20 percent)difference is necessary for some changes in taste to be detected, for instance. In contrast, a difference is noticeable if a musical tone becomes slightly higher or lower in pitch by only about 0.33 percent. Nor are the difference thresholds for the various senses the same for all people. In fact, there are great individual differences, often arising from experience or expertise. ⬛Professional food tasters know if a particular item or batch is a little too sweet, even if its sweetness varies by only a fraction of the 20 percent usually necessary to detect changes in taste. ⬛Furthermore, people who have lost one sensory ability often gain greater sensitivity in the other sensory abilities. ⬛Actually, Weber's law best fits people with average sensitivities and sensory stimuli that are neither very strong nor very weak, for example, not as loud as thunder or as quiet as a faint whisper. ⬛

3.It can be inferred from paragraph 2 that most people are more sensitive to

O changes in sound than to changes in taste

O changes in pitch than to changes in volume

O changes in sweetness than to any other change in flavor

O changes that are new than to changes that are familiar

4.The phrase “arising from" in the passage is closest in meaning to

O linked to

O dependent on

O resulting from

O strengthened by

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