Assimilation is a process whereby adjacent consonants become more similar to each other in manner or place of articulation in order to facilitate the flow of pronunciation. It can work in both directions, but the anticipatory (or regressive) type is usually assumed to be more common than the perseverative (or progressive) type. In the former, one or more preceding consonants become more similar to a following one, while in the latter, it is exactly the other way round. I personally find the alternative terms regressive & progressive highly misleading, which is why I would recommend using anticipatory and perseverative.

As a matter of fact, the word assimilation itself represents an example of assimilation, where the original prefix {ad} (from the Latin preposition meaning to or towards) has changed its shape to the phonologically conditioned allomorph {as}.

Anticipatory Assimilation

As the name implies, in this type of assimilation one or more consonants change so as to prepare for/facilitate the pronunciation of the following one. This change may be either in manner or place of articulation. The following table gives some basic examples of this type, first showing some of intra-word assimilation and then of inter-word assimilation in common combinations of words. In the examples prior to assimilation, pipe symbols indicate short prosodic breaks (i.e. pauses) between the original words. Please note that many of the examples below would usually, as a next step in the simplification process, also undergo elision in those cases where assimilation results in the two identical consonants following each other. Furthermore, the tighter link between two words created through assimilation may also lead to vowel reductions, i.e. contextual weak forms for some of the original words.

word/combination without assimilation assimilation trigger type of change
(Lancashire) hotpot [hɒt|pɒt] [hɒppɒt] bilabial plosive alveolar plosive ⇒ bilabial plosive
apprenticeship [əpɹɛntɪs|ʃɪp] [əpɹɛntɪʃʃɪp] palato-alveolar fricative alveolar fricative ⇒ palato-alveolar fricative
good bye [gʊd|baɪ] [gəbbaɪ] bilabial plosive alveolar plosive ⇒ bilabial plosive
good point [gʊd|pɔɪnt] [gəbpɔɪnt] bilabial plosive alveolar plosive ⇒ bilabial plosive
good night [gʊd|naɪt] [gənnaɪt] alveolar nasal alveolar plosive ⇒ alveolar nasal
ten points [tɛn|pɔɪnts] [tɛmpɔɪnts] bilabial plosive alveolar nasal ⇒ bilabial nasal
thin coat [θɪn|kəʊt] [θɪŋkəʊt] velar plosive alveolar nasal ⇒ velar nasal
give me [gɪv|miː] [gɪmmi] bilabial nasal labio-dental fricative ⇒ bilabial nasal

The final example in the table above shows fairly clearly how certain types of assimilation may also become reflected in spelling, i.e. that <give me> is represented as <gimme>.

  1. Try to think of some further examples of anticipatory assimilation.
  2. How common is this feature in other languages you may know?

Perseverative Assimilation

Assimilation that ‘goes in the other direction’, i.e. perseverative assimilation, is often said to be rarer than the anticipatory type. However, I am not aware of any study that has actually ever tried to quantify this exactly and the assumption may simply be based on the misleading fact that there are more opportunities for different consonants to assimilate in an anticipatory manner, i.e. that we have a fairly large number of potential types of similar processes. However, since perseverative assimilation tends to occur with certain highly frequent grammatical features or combinations of function words, we may have a smaller number of types, but in fact a very high number of incidences (tokens).

‘Grammatical Perseverative Assimilation’

The classic examples for this type of assimilation are:

Whenever we have a third form in brackets in the list above, we actually have a case of epenthesis, i.e. the insertion of a vowel, and thus the opposite of vowel elision. This happens in order to avoid having to repeat the same consonant twice in a row, which is quite difficult for non-nasal plosives and alveolar fricatives.

The thing to note in all these cases is that the assimilation in these cases presents itself in the continuation of the voicing feature. In those words that originally end in a voiceless consonant that would not end up getting reduplicated if the suffix were attached without epenthesis, the suffix itself is realised as voiceless, while words with the base ending in a voiced consonant end up having a voiced suffix. Essentially the same happens in cases that necessitate epenthesis, which are always voiced because the voicing of the epenthetic vowel carries on.


Another type of perseverative assimilation occurs with high frequency function words, generally determiners, that start with a weak fricative /ð/. As you can see in the table below, this type of assimilation occurs predominantly in a nasal environment, i.e. when the preceding (trigger) consonant is a nasal, although non-nasal consonants may also be involved. The main difference here seems to be that nasal consonants seem to favour a kind of ‘persistent’ assimilation that causes a gemination of the nasal consonant, whereas a non-nasal trigger often only provides a ‘temporary’ basis for later elision of the geminated consonant.

combination no assimilation assimilation trigger change
it wasn’t there [ɪtwɒznt|ðɛə] [ɪtwəznnɛə] alveolar nasal dental fricative ⇒ alveolar nasal
in the [ɪn|ðə] [ɪnnə] alveolar nasal dental fricative ⇒ alveolar nasal
in that case [ɪn|ðatkeɪs] [ɪnnəkkeɪs] alveolar nasal dental fricative ⇒ alveolar nasal
in this way [ɪn|ðɪsweɪ] [ɪnnɪsweɪ] alveolar nasal dental fricative ⇒ alveolar nasal
on that day [ɒn|ðatdeɪ] [ɒnnətdeɪ] alveolar nasal dental fricative ⇒ alveolar nasal
damn them [dam|ðəm] [damməm] bilabial nasal dental fricative ⇒ bilabial nasal
who’s that [huːz|ðat] [huːzzat] alveolar fricative dental fricative ⇒ alveolar fricative
how’s that [haʊz|ðat] [(h)aʊzzat] alveolar fricative dental fricative ⇒ alveolar fricative
walked past them [woːktpɑːst|ðəm] [woːktpɑːsttəm] alveolar plosive dental fricative ⇒ alveolar plosive
spot them [spɒt|ðəm] [spɒttəm] alveolar plosive dental fricative ⇒ alveolar plosive
give them [gɪv|ðəm] [gɪvvəm] labio-dental fricative dental fricative ⇒ labio-dental fricative
tell them [tɛɫ|ðəm] [tɛɫɫəm] alveolar lateral dental fricative ⇒ alveolar lateral

  1. Try to think of some further examples of perseverative assimilation.

Sources & Further Reading:

Knowles, G. (1987). Patterns of Spoken English: an Introduction to English Phonetics. London: Longman.

Roach, P. 2009. English Phonetics and Phonology: a Practical Course (4th ed.). Cambridge: CUP.