Assimilation is a phonological process where at least one parameter of a sign (handshape, orientation, location and movement) [Phonology 1] undergoes a change by adapting the feature of the similar parameter of the preceding and/or following sign. The adaptation of the features can be partial or complete. Assimilation can be observed in three ways: regressive assimilation, progressive assimilation, and bidirectional assimilation. In regressive assimilation the change of the feature is influenced by the following sign. In progressive assimilation the change of the feature is due to its previous sign. In bidirectional assimilation the change of the feature is caused by both the previous and following signs. Assimilation can be observed for different parameters of a sign such as hand configuration and movement.
The DGS examples below show progressive (a) and regressive (b) assimilation of the location parameter and regressive assimilation of the handshape parameter (c).
a. telephone (‘phone’) – number (‘number’) – telephone^number (‘phone number’)
(based on Becker, 2003: 116)
b. late (‘late’) – noon (‘noon’) – late^noon (‘afternoon’)
(based on Pfau & Glück, 1997: 35)
c. poss3 (‘her/his’) – parents (‘parents’) – poss3 parents (‘his/her parents’)
(based on Hohenberger, Happ & Leuninger, 2002: 119)