Orientation changes

One question that still needs to be answered is how these orientation features can be used to represent orientation changes. The different versions of the Leiden model have adopted Stack’s (1988) position that there is no need for movement segments, given two skeletal positions, and therefore that all movement can be considered to be feature change (van der Hulst 1993, 2000, van der Kooij 1994, Crasborn & van der Kooij to appear). Are all changes in orientation to be represented as a change in specification for relative orientation, then?

Looking at a sign such as TRANSLATE, illustrated in Figure 3.21, one could use the sequence [palm, dorsum]. This representation is possible because the ‘axis of rotation’ is parallel to the specified location. The axis about which the hand rotates in TRANSLATE runs from the root side of the hand to the tip side of the hand. The result of this rotation is that two dimensions of orientation change with respect to the specified location (the palm of the weak hand). The facing of the palm, dorsum, ulnar, and radial sides of the hand change, while the facing of the root and tip side remain constant.

Figure 3.21

TRANSLATE

More generally, it is true that if an object rotates around one axis, the orientation of both other axes perpendicular to the first one changes. The three axes are illustrated in Figure 3.22.

Figure 3.22

Changes in orientation in a three-dimensional object

For sign language, this can be paraphrased as follows: if the orientation of one specified degree of freedom of the hand changes, then two sides of the hand do not change orientation while the four other sides do. This is illustrated in Figure 3.23 for a change in ‘palm orientation’.

Figure 3.23 Change in palm orientation

The orientation of the root and tips stays constant in this gesture, while the orientation of palm, dorsum, ulnar and radial sides all change. Because of the focus of sign phonology on palm and finger orientation, three-way classifications have been made: there is a change in either palm or finger orientation, or a change in both. In reality, minimally two (and sometimes all three) dimensions of orientation change at the same time. Phonetically, there is nothing complex in a change in both finger and palm orientation (i.e. rotation about the radial-ulnar axis) compared to a change in either finger orientation or palm orientation alone. Nor do I know of any phonological property that would make a change in both palm and finger orientation more complex.

A representation in terms of a contour of feature values is impossible, however, if the axis of rotation is not parallel to but orthogonal to the specified location. In the sign DRUNK (Figure 3.24), the hand rotates about an axis that runs from the radial side to the ulnar side of the hand. Throughout the sign, the radial side of the hand keeps facing the specified location (and not the end setting as there is no setting change in this sign), namely the nose.

Figure 3.24

DRUNK

Thus, there are some signs with orientation changes around only one axis that cannot be described by a sequence of relative orientation features. In these signs the specified relative orientation value stays constant, or in other words, the axis of rotation is perpendicular to the end setting (or the place of articulation). Further examples include FAR-AWAY, LOCKED, SHY, and FIRST, and POLITICS (Figure 3.25).

Figure 3.25

POLITICS

The arrow indicates the axis about which the hand rotates, and just like the fingertips, which are selected for relative orientation, it points towards the palm of the weak hand, which is specified as the major location. The movement could be described by saying that the orientation of the palm in space is first down and then back, for example.

In the literature, changes in orientation are also often described by referring to articulatory gestures, such as forearm rotation and wrist extension (Stokoe 1960, Nagahara 1988, Brentari 1998). For example, in the case of POLITICS, one could say that the orientation is first ‘prone’ and then ‘supine’. In the first ASL analysis, Stokoe (1960: 87) distinguished “twisting motion” of the forearm (pronating, supinating, and oscillating) from “carpal motion” (nodding or shaking wrist).

Changing hand orientation about one axis can indeed be accomplished by simple movement at just one joint (e.g. rotation of the forearm, flexion at the wrist, sidewards flexion at the wrist; cf. the definitions and illustrations in Brentari 1998: 155-157), but I claim that these articulatory categories are not a good way of describing the sign’s phonological form. In the case of POLITICS (which is almost identical to MEANINGASL), for example, the change in orientation is articulated by forearm rotation alone in case the wrist and MCP joints are fully extended, as in Figure 3.25. However, in an alternative articulation, where the wrist and/or MCP joints are flexed, a more complex combined movement of the forearm and wrist occurs, in such a way that the orientation and change in orientation of the selected index and middle fingers are the same as in Figure 3.25. This is illustrated in Figure 3.26.

i. Initial state: forearm prone, wrist slightly flexed, MCP joints flexed

ii. Final state: forearm supine, wrist extended and slightly adducted, MCP joints flexed

Figure 3.26

POLITICS, alternative articulation

While the forearm rotates, the wrist flexes and adducts in order to limit the change in orientation of the fingers to only one dimension (the same as in Figure 3.25). Hypothetically, the reason why this articulation is sometimes preferred is because it greatly reduces the articulatory effort involved: the shoulder does not have to be abducted as much as in Figure 3.25 in order to realize the desired orientation of the finger tips. The generalization about the movement in the different realizations is a perceptual one, then, referring to the change in orientation of the palm side of the selected articulator (or the back, ulnar, or radial sides). Although a change in position of the forearm is certainly involved, it is not the key feature of the sign that changes. Figure 3.27ii illustrates the final state of the sign in 3.26 that would result from only supinating the forearm.

i. Initial state: forearm prone, wrist slightly flexed, MCP joints flexed

ii. Final state: forearm supine, wrist slightly flexed, MCP joints flexed Figure 3.27

Non-existent version of POLITICS

I propose to represent all changes in orientation by reference to the three axes about which movement can occur: the longitudinal axis, the radial-ulnar axis, and the front-back axis. These are illustrated in Figure 3.28.

Figure 3.28

Three axes of rotation for articulator [all; extended]

The definition of these three ways to rotate the articulator does not contain any information about the articulation that is used to produce them. Although the involvement of some articulations (such as forearm rotation) will be more frequent than others (such as MCP flexion), this information is not included in the lexical specification of signs, but rather a matter of phonetic implementation. In terms of the nature and definition of the orientation change features, this proposal differs markedly from the articulatory definitions in Brentari (1998); the two proposals resemble each other both in proposing six different features and in characterizing these changes as ‘movements’ rather than changes from one value to the next.

Each axis can rotate in two directions, clockwise and counterclockwise. The degree of rotation is not lexically distinctive. The size of the rotation is generally between 90 and 180 degrees. I hypothesize that the actual size is predictable, and that in part articulatory factors play a role in limiting the movement size. If a movement is articulated by wrist extension, for example, as in Figure 3.29ii, then the movement size will be limited by the initial position of the wrist. The directions ‘clockwise’ and ‘counterclockwise’ should be interpreted by looking in the direction

of the arrows in Figure 3.28, and are always assigned from the perspective of the right hand. Examples are presented in Figure 3.29.

i. Longitudinal: clockwise, FIRST

ii. Longitudinal: counterclockwise, TWENTY

iv. Radial-ulnar: counterclockwise, DRUNK

v. Palm-dorsum: clockwise, ERECTION

vi. Palm-dorsum: counterclockwise, READY Figure 3.29

Changes in orientation

The advantage of using these axes to specify orientation changes is firstly that there is no longer a privileged role for any side of the hand, and secondly that this movement can be interpreted without reference to absolute directions in space. For example, in the case of TWENTY, not only the palm orientation changes, but also the orientation of the dorsum and the radial and ulnar sides of the two selected fingers. Furthermore, the rotation will be the same no matter whether the relative orientation

(in TWENTY [root] facing a [horizontal plane] in neutral space) is faithfully realized or not. As I argued in §3.4.2, there is no fundamental difference between the dynamic terms on the one hand and changes in static terms on the other. Dynamic terms such as ‘clockwise’ and ‘counterclockwise’ might be decomposed into sequences of values.

Given the limited range of lateral motion (adduction/abduction) of the wrist and the MCP joints (about 50 degrees for the wrist, cf. Luttgens, Deutsch & Hamilton 1992), it is not surprising that palm-dorsum rotation is so infrequent. In cases where the wrist and MCP joints are extended, this is the articulatory action that results in the perception of rotation around the palm-dorsum axis. Similarly, given the large range of motion of the forearm (about 160 degrees, cf. Luttgens et al. 1992), it is not surprising that the perceptual result typically associated with it when wrist and MCP joints are extended is so frequent (viz. rotation around the longitudinal axis). However, the gesture [forearm rotation] can also be used to articulate rotation about the palm-dorsum axis, if the extended fingers are at about a 90 degree angle to the forearm. This angle can be articulated by either wrist or MCP flexion, or both. For example, the sign MORNING, which is typically articulated by outward shoulder rotation (Figure 3.30) can also be articulated by supination of the forearm (Figure 3.31), depending on the state of the wrist and MCP joints.84

Figure 3.30

MORNING, (primarily) articulated by outward shoulder rotation

84 _{In both signs, these articulations are typically accompanied by smaller movements of the other joints,} which ensure that the orientation of the other degree of freedom remains relatively constant and that the movement is in the frontal plane. These additional joint movements play less of a role than in the example of POLITICS above (Figure 3.25), yet the effect is the same: different joints cooperate to attain perceptually similar effects.

Figure 3.31

MORNING, (primarily) articulated by forearm supination

In most changes in orientation in SLN, there is a change in orientation around only one axis. Changes in orientation around two axes are very rare, if they exist at all. A possible example is the sign QUICK (Figure 3.32).

Figure 3.32

QUICK, a change in orientation by rotation of the selected index finger about two axes

The sign QUICK contrasts with THOUSAND (Figure 3.33), in which there is only rotation about the palm-dorsum axis.

Figure 3.33

THOUSAND

It remains a question for future research whether there are more signs such as QUICK with a complex orientation change, and whether there is a more simple specification for this sign than a double orientation change. For now, I propose the specification for this sign includes a combination of [longitudinal axis: clockwise] and [palm- dorsum axis: counterclockwise].