This usage-based study of Indonesian morphology demonstrates the effect of frequency on the occurrence of the two most common verbal prefixes in a corpus of spoken language. This study establishes systematicity in the (non)use of these affixes in colloquial Indonesian, demonstrates the role unaffixed verbs play in establishing informal affect between speakers, and gives us a better understanding of the nature of the colloquial language vis-à-vis other varieties of Malay/Indonesian.

Background. Indonesian employs a limited set of highly productive derivational affixes. One characteristic of colloquial Indonesian is the frequent lack of affixation that would be considered obligatory in the standard language. This phenomenon has sometimes been characterized as an unsystematic feature of casual speech. This study investigates whether there is in fact systematicity in 'affix dropping' and if so, what are the patterns and motivations for (non)use of affixes in colloquial Indonesian. I look specifically at the occurrence of the actor-voice (so-called 'active') prefix meN- and the intransitive prefix ber- in a corpus of naturally occurring informal Indonesian conversational interactions.

Findings. First, use of these verbal prefixes is in fact frequent. Second, tokens of unprefixed verbs that do occur are not randomly distributed through the data. Rather, they tend to be most frequent among the commonest verbs in the corpus, while the less common verbs are more often produced with their full standard morphology. Many of these verbs appear to be unprefixed primarily due to their frequency, while there appear to be additional converging motivations, such as grammaticization, for the unprefixed nature of others. Finally, the general 'affixless feeling' of colloquial Indonesian is augmented by the fact the most frequent verbs in the corpus comprise the small number of verbs which also do not take affixes in the standard language. This suggests that 'affix dropping' in colloquial Indonesian is the continuation of a process that occurs to a more limited degree in the standard language. This study suggests that the variety of colloquial Indonesian investigated here is best viewed as a stylistic variant of the standard language rather than as a separate variety. Thus while speakers can employ all the resources of the standard language when necessary, the affective function of marking informal interaction is carried out by a limited number of frequently occurring features, including the absence of affixation on the most common verbs.