The general public has a very clear attitude towards irregularities (such as irregular verbs) in language: they are imperfections to be despised. Linguists and psychologists, however, have a completely different idea, based on research work of the past decades. In this lecture, I will present three ideas that are now widely accepted by researchers but may surprise the public.

(1) Irregularities are useful. To say a regular verb in a sentence, the speaker has to quickly combine the root and affix (for example, in English, cook + ed to create cooked). This action requires time and mental effort that can be measured in experiments. To say an irregular verb, the speaker simply has to find it in memory (for example, ate in English, instead of eat + ed), which is measurably faster. Regular verbs have to be "constructed," but irregular verbs are already "ready" for pronunciation.

(2) (Ir)regularity changes over the lifespan. Infants during the first year of life treat verbs that are traditionally considered regular as irregular. That is, they treat forms like cooked as indivisible units, not as combinations (cook + ed) as older infants and adults do. Gradually, they realize that such forms are separable and regular. The opposite also happens: infants often treat (traditionally) irregular verbs as regular and formulate a rule that they later abandon.

(3) Adults who learn a new language acquire (ir)regularity less effectively than infants. For example, non-native speakers of English simply omit the past tense of verbs (and say cook and eat instead of cooked and ate) much more than infants do. It is still uncertain why this phenomenon occurs, but one promising idea is that it relates to a known change in memory capacity over the lifespan. Infants have a very strong "procedural memory" and can thus effectively apply linguistic rules (to "construct" verbs while speaking, for example), but this memory capacity begins to weaken during maturation (and during the shrinking of the basal ganglia in the brain) and perhaps because of this, one acquires the regularity and irregularity of words less effectively.

In summary, one can easily understand why the public dislikes irregularities in language, but from a scientific standpoint, irregularities are a natural and useful part of the normal functioning of language and an important tool for a deeper understanding of human language in general.