A technique for studying learning. Words, syllables, digits, or other items are learned in pairs, and the subject is later tested on his ability to give the second member of the pair when the first is presented. In a typical paired associates experiment, the names of states are paired with colors: Ohio-Red, Delaware-Blue, etc. After they are presented together a number of times, the names of the states are given, and the subject tries to respond with the correct colors. Any two items may be paired in this fashion. To control the exposure time, they are usually presented on a memory drum (PLATE 32).This type of procedure has two major advantages. First, it is closely related to actual experience, since much of our thinking is a chain of associations, acquired by “serial learning,” in which one response becomes a stimulus for the next, as in counting to one hundred, playing a piece of music, or reciting a poem. It is also relevant to more specific tasks, such as learning a foreign language vocabulary, since we pair the new words with their English equivalents. Second, the procedure lends itself to experimental investigation of many aspects of the learning process, particularly proactive inhibition, retroactive inhibition, and transfer of training.In testing for proactive inhibition, or forward-acting interference, the experimenter attempts to find out whether learning one set of pairs will interfere with the learning of subsequent pairs. Here the subject leams to associate the states with one set of colors, and later with a second set of colors. If the second learning takes longer, as it usually does, it is evidence for proactive inhibition. The subject may then be asked to relearn the first set of associations, and if he takes significantly longer than he did the first time he learned it, this is taken as evidence of retroactive or backward-acting inhibition.The object of the transfer of learning tests is to discover whether previous learning can have a positive effect on subsequent learning—for example, whether studying one language helps us with another. A typical experiment consists of learning paired nonsense syllables such as MIR-PED, TEC-ZOX, REQ-KIV, and then learning another list in which the first syllables are changed. Does it help or hinder us if we already know the second syllables The answer is that it usually helps. However, it has been found that the amount of transfer varies with different syllables. If the new syllables are similar to the old ones, the effect is considerably stronger than if they are not similar. This means that an American will probably learn Spanish more easily than Chinese.