meanings in the lexicon (or "mental dictionary") or are constructed using morphological rules. Leak and rose, for example, would be stored as mental dictionary entries, but the words leaked and roses do not need to be memorized separately, as they can be easily constructed by applying "rules" that add the appropriate suffixes (i.e. "adding '-ed'" to form the past-tense form and "adding '-s'" to form the plural form, respectively). In analyzing the errors English-speaking children make (such as the over-application of morphological rules to create words like mouses and bringed), Pinker concludes that irregular forms are not remembered in terms of the supposed rules that produce them (such as a rule that would produce sleep/slept, weep/wept, keep/kept, etc.), but instead are memorized separately, while the rule for forming regular past-tense forms (i.e. "adding '-ed') applies by default. Research The Words and Rules model contradicts previous orthodox Chomskyan ideas hypothesizing that several irregular past tense forms arise from rules applied to verbs with phonological similarities (as seen with the example of sleep, weep, and keep above). He particularly notes discrepancies that would arise in application of a rule-based theory, as in the verb steep and its past-tense form steeped as opposed to steep/stept. Pinker accepts the notion of pattern associators from the connectionist model, which states that families of irregular verbs obtain their past-tense forms from associations between the phonological features of these verbs and those of their irregular past-tense forms. Pinker found that some adults and children will form the past-tense form splung from the novel verb spling in line with the pattern seen in fling/flung and cling/clung. However, he shows research showing these sorts of generalizations to be exceedingly rare in comparison to the over-application of the regular past-tense rule to these verbs. He additionally points out that connectionist models tend to produce odd past-tense forms of verbs that otherwise have regular past-tense forms (e.g. membled for mail). References External links Pinker's website on Words and Rules Dig-dug, think-thunk by Charles Yang, a critical review of Words and Rules 1999 non-fiction books Cognitive science literature Morphology books Works by Steven Pinker English-language books