A nonsense syllable is a string of letters that amounts to a single syllable that is devoid of any meaning. The word "one," though it is only one syllable, is not nonsense because it is a word that conveys meaning. The syllable "kuq," on the other hand, at least in the English language, is a nonsense syllable because it is not a word and conveys no meaning. In general, nonsense syllables are at least "word like," in that they can be phonetically pronounced. Nonsense syllables are commonly used in psychological experiments regarding speech, understanding, and memory, particularly in the area of cognitive psychology.
In general, a nonsense syllable is designed to be devoid of any kind of meaning but to still be pronounceable. In general, such syllables are composed of three letters: a consonant followed by a vowel followed by another consonant. Such combinations of letters are, in nearly all cases, pronounceable, and many such combinations have no meaning. Similar constructions, such as a vowel followed by a consonant followed by a vowel — and even some constructions with four or more letters — are also used. Interestingly, despite the fact that a nonsense syllable is crafted to have no explicit meaning within the language, experiments in cognitive psychology have indicated that people do associate meaning with many such syllables.
The level of meaning that people assign to nonsense syllables is quantified through the "association value." A variety of different types of experiments in cognitive science are used to measure the association value of a given syllable. In one type of test, the test subject is simply asked to respond "yes" or "no" to the question of whether or not a nonsense syllable has meaning. In another, the test subject is given a set period of time to write a list of all of the words that he associates with a given nonsense syllable. In both cases, an association value is calculated based on the collected results of a large body of test subjects.
Nonsense syllables are often studied in connection with human learning and memory. The learning and memory of foreign names, for instance, is related to nonsense syllables, as foreign names are often composed of syllables with low association values. Some elements of child learning can also be studied with nonsense syllables. In the "wug test," for instance, a child is asked to give the plural of the nonsense syllable "wug." His pronunciation of the plural, which could be "two wug," "two wugz," "two wugses," "two wug-ez," or something else entirely, demonstrates his grasp of plural constructions in the English language.