Metathesis is a phonological process that changes the order of phonemes in a sign. Consider, for instance, those signs requiring the hand(s) to move from one location to another. Generally, the order in which the two locations are reached is fixed (e.g. from location 1 to location 2). In those signs allowing metathesis, this order can be reversed (e.g. from location 2 to location 1). Importantly, such phonological change does not produce any change in meaning.
In LIS, as far as we know, metathesis is attested in a few signs only. Below, we present a couple of examples: patience and facebook. The sign patience involves a change of location, usually from the contralateral to the ipsilateral area of the chest, as in (a). In some cases, the sign undergoes metathesis in that the location change is from the ipsilateral to the contralateral area of the chest, as shown in (b). Crucially, the meaning of the sign remains the same.
a. patience (citation form)
b. patience (metathesis)
A similar case is a variant of the sign facebook. It is articulated by shifting the B handshape from the contralateral to the ipsilateral cheek (a). By effect of metathesis, the order of the two locations can be reversed, i.e. from the ipsilateral to the contralateral cheek, as shown in (b). Crucially, the meaning of the sign remains the same.
a. facebook (citation form)
b. facebook (metathesis)