Assimilation is a process by which a sign takes on (i.e. assimilates) one or more features of a phoneme belonging to a neighbouring sign. This phonological process can affect all phonological parameters of a sign. The most typical case is handshape assimilation, which occurs when the handshape of a sign becomes more similar to the handshape of a sign close to it. Below, we can observe an example of assimilation.
year^one foggia ix1 commute
‘I commuted to Foggia for one year.’
The first-person pronoun (ix1) is not produced with its canonical handshape (extended index finger), but with the handshape of the following sign (flat open 4 in the sign commute). In this example, assimilation operates backwards because the handshape of commute influences the handshape of the preceding sign. This process is known as regressive (or anticipatory) assimilation.
Assimilation can also occur in the opposite direction. When the change operates forwards, it is called progressive (or perseverative) assimilation. It is exemplified below.
work continue so_far
‘I have kept working.’
In the example above, the symmetrical two-handed sign so_far is not produced with its canonical handshape (extended index finger), but with the handshape of the preceding sign (extended 5 in the sign continue).
Another possibility is the so-called bidirectional assimilation, a combination of progressive and regressive assimilation. In this case, both the preceding and the following forms exert an influence on the form undergoing assimilation.
future ix1 commute be_fed_up
‘In the future, I'll be fed up to commute.’
In this example, the first-person pronoun (ix1) is not produced with its canonical handshape (extended index finger), but with the handshape of both the preceding and following signs (future and commute are articulated with flat open 4).
It is important to notice that assimilation can be total or partial. In total assimilation, all features of the neighbouring form are copied. By contrast, in partial assimilation, only some features are copied. To see the difference between these two types of assimilation, we observe different realisations of intelligent. This is a compound sign formed by the sign head and a Y-handshape classifier conveying the concept of a large amount. In its original form, the first part of the compound is articulated with extended index finger, as shown below.
intelligent (citation form) (recreated from Battaglia, 2011: 198)
In a variant of intelligent, the first part of the compound undergoes partial assimilation. It copies only one particular feature of the handshape of the second part, namely extended thumb. Therefore, the resulting handshape includes extended index finger and thumb.
intelligent (partial assimilation) (recreated from Battaglia, 2011: 198)
In another variant of the sign, the first part of the compound undergoes total assimilation. It copies all the features of the handshape of the classifier: both extended thumb an extended pinky finger. Therefore, the resulting handshape includes extended index finger, thumb, and pinky.
intelligent (total assimilation) (recreated from Battaglia, 2011: 198)
As introduced above, assimilation can occur with all phonological parameters. In other words, a sign can assimilate the handshape, location, movement, or orientation of a neighbouring sign. We provide below an example of orientation assimilation. The cardinal two is systematically articulated by some LIS signers (including our informant) with inward palm orientation (LEXICON 3.10.1.1).
two (citation form)
However, if two is followed by week, a two-handed sign requiring outward palms, it can assimilate its orientation.
two week
‘Two weeks’
Furthermore, we illustrate the process of location assimilation comparing the two examples below. The aspectual marker done is used to indicate that an event happened before the time of utterance (LEXICON 3.3.1). This sign typically follows the main verb and is produced in the neutral space. As shown in (a), both the verb and done are articulated in an unmarked area in the signing space. However, when done follows a verb that is articulated in a different location, assimilation might occur. As shown in (b), done follows the verb run, which is characterised by a linear contralateral movement. The informant is left handed, so the endpoint of run is in the right area of the neutral space. The sign done assimilates this marked location, and thus is articulated on the right side as well.
a. g-i-a-n-n-i ixa house buy done
‘Gianni bought the house.’ (based on Zucchi, 2017)
b. g-i-a-n-n-i ixa arunb doneb
‘Gianni ran.’ (based on Zucchi, 2017)
Assimilation can also apply to a more local domain. We call this process internal assimilation. Some two-handed signs, whose citation form requires that the hands articulate two different handshapes, can undergo assimilation from the dominant to the non-dominant hand. For example, the two-handed sign week is typically produced with extended 5 on the non-dominant hand and L handshape on the dominant hand (a). Recall that when both hands behave as active articulators in two-handed signs, they typically share the same handshape (PHONOLOGY 1.4.1). This sign is articulatory exceptional because, although both hands move, two different handshapes are used: 5 in the non-dominant and L in the dominant hand. In a variant of week, the non-dominant hand takes on the handshape of the dominant hand (b). As a result, the L handshape is employed by both hands. This assimilation process might be motivated by the principle of ease of articulation.
a. week (citation form) (recreated from Radutzky, 2009: 21)
b. week (assimilation) (recreated from Radutzky, 2009: 21)
Internal assimilation can also occur in asymmetrical two-handed signs, i.e. signs produced by both hands in which only the dominant hand behaves as active articulator. For example, the verb try in its original form is produced with extended 5 on the non-dominant hand and V handshape on the dominant hand, which is the only hand moving (a). In a variant of try, assimilation occurs from the handshape of the dominant to that of the non-dominant hand (b). As a result, the V handshape is used by both hands.
a. try (citation form) (recreated from Radutzky, 2009: 20)
b. try (assimilation) (recreated from Radutzky, 2009: 20)