A Grammar of Sign Language of the Netherlands (NGT)

Under assimilation, at least one phonological feature of a sign takes the same value as the relevant phonological specification of a preceding sign (progressive assimilation) or following sign (regressive assimilation). This process can affect every type of phoneme (see PHONOLOGY, Chapter 1). For example, assimilation of a handshape feature may result in two signs being signed with the same selected fingers, although their original citation forms have different specifications for finger selection. Handshape assimilation is often seen in cliticization (PHONOLOGY 3.3.2), such as in the example in Figure 2.54 (repeated from PHONOLOGY 2.2.1), in which the index sign, usually signed with a B-handshape, is signed with a handshape that closely resembles the handshape of the following lexical item sign (articulated with a >-handshape). This is thus an example of regressive assimilation.

Figure 2.54. A case of regressive handshape assimilation.

The example in Figure 2.55 exemplifies progressive assimilation of location. The sign problem (see Figure 3.55a in MORPHOLOGY) is usually signed at the head, but in Figure 2.55, it is signed lower to adapt to the location of the preceding sign not,  which is articulated in front of the signer’s body.

not problem

Figure 2.55. A case of progressive location assimilation

(CNGT0617, S29, 00:07.500-00:08.250).

Other features that are sensitive to assimilation are finger configuration, finger orientation, and movement features.