Monday, October 21st @ 3 PM, Harper 140

Variation in fingerspelling: time, pinky extension, and what it means to be active

This talk will look at two sources of variation in fingerspelling of American Sign Language: overall timing, and one aspect of hand shape.

Reported fingerspelling rates have considerable variation (a lower bound of ~125msec per letter; an upper bound of ~400msec) (Quinto-Pozos, 2010; Bornstein, 196; Hanson, 1981; Wilcox, 1992; Geer, 2010}. Most of these did not analyze individual letter-segments, but rather, the length of the word and divided by the number of letters expected. Some used a segment based analysis which showed word medial letters are fingerspelled quicker than initials or finals  (Reich, 1977). Emmorey (2011) showed breaking at a phonological-syllable-boundary aided fingerspelling perception. Building on these studies, we have collected and analyzed timing data from 4 ASL signers. We replicated many of the previous findings, and additionally found that there are large differences between different letter types, large individual differences, as well as differences in rate based on the type of word being fingerspelled.

We show that not only position, but also type of letter and signer have a large influence on the timing properties of ASL fingerspelling. Also, it is important to look at fingerspelling segment by segment because there are large differences based on the kind of segment being fingerspelled. Finally, there are large individual differences that are obscured by looking at rate simplistically (just holds, just transitions, or letters per minute).

It is widely assumed in the articulatory phonology literature that when an articulator is not active (unspecified in the gestural score) it assumes a neutral state. One example of this is that the velum, when not active, assumes a closed position; only when it is actively opened does it deviate from that position. This assumption makes predictions about speech that seem to be fairly robust: nasal sounds are more marked than non-nasal, and nasalization spreads from nasal sounds, etc. This neutral position, however, is at odds with the position that the velum assumes naturally when people are at rest (eg not speaking), which is open, allowing for air to be drawn into the respiratory system from the nose or mouth. This being the case, there must be some muscular activity on the velum during periods that have previously been described as inactivity in order to keep it closed. One solution to this apparent problem is to specify gestures for periods previously assumed to have no activity, although these gestures would necessarily be weaker than active articulator gestures.

There are two major predictions that come from the fact that the targets associated with nonactive gestures are not a physiologically neutral state, but rather a state that is default for speech. First, it is possible that the targets for nonactive gestures will differ cross linguistically with different languages having different default states. This is supported in work on spoken languages looking at default targets of nonactive articulators, or what are described as articulatory settings which vary from language to language (Wilson, 2006; Wilson, 2006; Gick, 2004). Second, it’s possible that the targets for nonactive gestures will vary depending on the targets of the active gestures. This will be used in the development of the articulatory phonology model of handshape proposed here for the configuration of the nonactive (nonselected) fingers.

Since the earliest theories of sign language phonology, handshapes have divided the fingers into selected and non-selected groups (Mandel (1981), ff). Mandel describes the selected fingers as the foreground and the nonselected fingers as the background. This talk presents an articulatory model of handshape which explicitly links this distinction to the distinction of active and inactive articulators used widely in speech (Browman, 1992). This link makes critical, testable predictions about the nature of handshape variation due to coarticulatory pressure: The hand configurations of a letter vary predictably based on surrounding context, constrained by the following tendencies: 1. The nonselected fingers are targets of coarticulatory pressure. 2. The selected fingers are the likeliest sources of coarticulatory pressure. The articulatory model of handshape is based on articulatory phonology (following Browman (1992)) and can explain the phonetic implementation of handshape from phonological specifications. It explains variation due to articulatory effects (eg coarticulation) because it uses dynamic articulator gestures. That is, the articulators that make up the hand are not static, sequential configurations (ie discrete units), but rather individual articulator gestures overlapping across segments. This ability to model gradient phonetic implementation and contextual variation represents a critical improvement over previous phonological models.

An analysis of coarticulation of pinky extension revealed a puzzling fact: There is less pinky extension coarticulation in handshapes where the pinky is selected and flexed (-A-, -S-, -E-, and -O-) compared to other handshapes where the pinky is nonselected and flexed. Despite having the same phonetic realization in both (flexed), the pinky behaves differently with respect to coarticulation depending on its membership in the selected fingers group. This follows directly from the articulatory model of handshape: in handshapes where the pinky is selected and flexed, there is less pinky extension as a result of coarticulation because the pinky is an active articulator, which suppresses coarticulatory pressure from surrounding articulator gestures because the flexion is associated with an (active) articulatory gesture.

The articulatory model of handshape provides a concrete and principled way to convert the phonological specifications of handshape into phonetic configurations using a model of articulator targets and gestures developed for speech. Additionally, the articulatory model of handshape correctly predicts how the active or inactive status of particular articulators will affect variation in natural production.