4.1 Replacement of visual information by pre-existing items

As we pointed out in Section 1, one natural question which arises in investigating a tactile sign language is how Deafblind signers make up for the loss of information resulting from the fact that non-manual markers (NMMs) can no longer be perceived. Interestingly, only the signer who had residual vision occasionally used NMMs, the others did not use NMMs anymore. One natural expectation is that, whenever a manual sign is available that provides an alternative way to convey the information conveyed by an NMM, it will be used in place of the NMM. This is what we observed.

4.1.2 Modifiers

In LIS manner adverbs and degree modifiers are often articulated by altering the movement component of verbs. For example, in order to translate sentence (4) in LIS, the manual sign EAT is performed repeatedly with a fast movement (we indicate this way of incorporating the adverb into the verb by means of the gloss in (5)). A separate manual sign for the adverb can also be used to express the same meaning (as indicated in (6)), although the option of incorporating the adverb into the verb is preferred:

(4)	Gianni eats fast.

(5)	LIS
	GIANNI EAT(fast)

(6)	LIS
	GIANNI EAT FAST

In LISt the preference pattern is reversed: when a separate sign for the manner adverb is available, our Deafblind informants tend to use a sequential construction in order to express manner modification. Thus, in our LISt corpus we normally find occurrences like (7), which in LIS would be more commonly expressed by modification of the verb movement:

(7)	a.	LISt
		SUN BEAT-DOWN STRONG
		‘The sun beats hard.’
	b.	LISt
		TEMPERATURE HOT STRONG
		‘The temperature was very hot.’
	c.	LISt
		TIRED STRONG TIRED STRONG
		‘(He) was very tired.’
	d.	LISt
		HOT HEAVY
		‘It was very hot.’

For example, while the adverbial modification in LISt sentence (7a) is expressed by the separate manual sign STRONG, in LIS the same meaning is usually expressed by altering the movement of BEAT-DOWN in the following way: the movement becomes extremely slow and it is produced with increased muscular tension, indicating greater intensity.

Since a difference (e.g. in speed or intensity) between various kinds of movement of the hands can in principle be perceived in the tactile modality, it is not immediately obvious why LISt users should disfavor the strategy consisting in altering the movement component of verbs to express manner adverbs and degree modifiers. However, this fact can be explained by looking at some further facts concerning adverbial modification in the visual language. Consider how English sentences (8)–(9) can be expressed in LIS:

(8)	Gianni cut the onion.

(9)	Gianni cut the onion finely.

As shown in Figure 6, the presence of the adverbial modifier “finely” is signaled mainly by the facial expression of the signer while the verb is signed.⁵ Given that in LIS, facial expressions commonly co-occur with the verb to express adverbial modification, it’s clear that the strategy of expressing adverbial modification by simultaneous rather than sequential means may result in loss of information if adopted generally in LISt. This may account for a general preference to use a separate sign for the adverb in LISt: given that the simultaneous strategy cannot be used consistently, LISt signers tend to consistently adopt the sequential strategy.⁶

Figure 6

Adverbial modification by NMM.

So far, the differences we have observed between LIS and LISt reflect the strategy of maximally exploiting the resources that are already present in LIS to avoid loss of information. The changes we observed may be entirely explained in terms of adaptive choices that systematically allow for an effective way of communicating, while no genuine linguistic innovation has been observed yet.

4.2 Emblem lexicalization

In some cases, adverbial modification involves the introduction of new items in the lexicon of LISt. One common gesture in Italian culture is a horizontal B handshape with the thumb up, the palm facing the signer, moving down and up repeatedly with a rotation of the wrist, as shown in Figure 7. It means the same as “very” or “much” and it is conventionalized, namely, it is an emblem, as it is called in the literature on gestures (see Kita 2001). For convenience, we gloss it as VERYMUCH, although we should emphasize that in LIS it is a gesture, not a sign:

Figure 7

The emblem VERYMUCH.

Although this gesture is occasionally found in visual LIS, our LIS informants perceive it as not being part of the lexicon of LIS, but as a gesture borrowed from the spoken culture. In LISt, VERYMUCH is often used, some occurrences are shown in (10) (as mentioned in footnote 4, we use ‘+’ to indicate repetition):

Crucially, in LISt, we observed a way of expressing augmentative meaning which we do not observe in LIS. For example, in (11), illustrated in Figure 8, the hand configuration in the expression glossed as WATER VERYMUCH is that of the noun WATER (5 handshape) and not that of VERYMUCH (B handshape), while the movement is that of VERYMUCH:

Figure 8

WATER VERYMUCH.

In (11), the handshape of the sign WATER is retained by the item VERYMUCH, in a way similar to a phonological process of perseverative assimilation in spoken languages, in which a segment retains a feature of a previous segment (like the devoicing of the English plural morpheme /z/ when preceded by a voiceless consonant). After identifying this LISt innovation for a first time in one signer, we looked for similar cases to see if this strategy is used systematically and we found that it is. More specifically, we fully analyzed one session of the “telephone game” task. Three out of the four signers who participated in this task produced VERYMUCH with perseverative assimilation. They did it respectively five, two and four times in the time frame of approximately 3 minutes during which they reproduced the version of the story they had received. Another example produced by another Deafblind signer is:

Sentence (12) can be analyzed as another case of perseverative assimilation, since the hand configuration in the item glossed as BEAUTIFUL VERYMUCH is that of the adjective BEAUTIFUL (F handshape),⁷ while the movement is that of VERYMUCH.

Only one of the signers who took part in the telephone game did not use the emblem VERYMUCH, since he adopted a different strategy to express augmentation, namely he used the LIS sign MANY, which is normally used with count nouns, with an adverbial function which corresponds to the meaning of VERYMUCH.

One thing that needs to be explained is why VERYMUCH is used systematically and undergoes phonological assimilation in LISt, but not in LIS. As assimilation is a process available in LIS as well, the difference can be explained if VERYMUCH is part of the lexicon of LISt but not of LIS. The diachronic transition from emblem to sign is a well-known independently attested phenomenon in sign languages (Janzen 2012). This is also true for LIS, where some gestures of the hearing culture have been lexicalized, one example being the sign STEAL. One plausible reason why VERYMUCH has been lexicalized in LISt but not in LIS may be related to the tendency we observed to linearize modifiers in LISt: we argued that in LISt modifiers tend to be signed sequentially rather than simultaneously because adverbial modification by simultaneous means often involves NMMs (although simultaneous manual cues, like speed and intensity, could also convey the augmentative meaning). Given this tendency to linearize modifiers in LISt, it becomes natural for LISt signers to have a separate manual sign to express ‘very’ or ‘much’.

As the lexicalization of VERYMUCH is part of a process by which the information presented simultaneously in LIS is presented sequentially in LISt, it parallels changes in the lexicon of tactile ASL that are described by Edwards (2014). Edwards reports that innovations in the production of asymmetrical two-handed signs emerged in the context of the “pro-tactile” social movement in the Seattle community of Deafblind signers. Members of this movement decided to hold workshops among them without the mediation of interpreters and faced the challenge of communicating with multiple Deafblind interlocutors. In this context, a three-person mode of communication was established in which a Deafblind person signs to two interlocutors at the same time. In a three-person configuration, the dominant hand of the signer signs to interlocutor 1 while the non-dominant hand signs to interlocutor 2. Obviously, in the three-person configuration two-handed signs cannot be transmitted unless they are turned into one-handed signs. This is what happens. For example, the innovative form of the sign can be produced by having the same hand assuming first the role of the dominant hand in the original version of the two-handed sign, and then the role of the non-dominant one. Under this innovation, two configurations that were simultaneously produced by two hands become sequentially produced by just one hand.

In this Section we have argued that LISt users introduced a new manual sign in the lexicon, corresponding to an augmentative adverb. This allows information that is transmitted simultaneously in LIS to be transmitted sequentially in LISt. This transition is arguably motivated by perceptual constraints, as processing of simultaneous information is easier in the audiovisual channel than in the haptic one. Importantly, the new innovation interacts with phonology.

In the next Section we turn to a difference between LIS and LISt which involves a functional sign.

4.3 Change in pointing signs

Another area in which we studied the differences between LIS and LISt is the production of pointing signs.

In LIS, as in other visual sign languages, NPs are associated with locations in space, commonly called ‘(Referential) loci’. Either the NP is directly signed in the locus or, if this is not possible (for example because the noun is signed on the body of the signer), the association between the NP and the locus is done by pointing to, or directing the gaze towards, a specific point in space, which becomes the locus of the NP. If the referent of that NP is present in the utterance context, the pointing is towards its actual location. If the referent is not present, it is assigned a point in the neutral space. Each NP can be assigned a distinct location, and in principle each location can uniquely identify a referent. The point in the neutral space to which the index finger is pointing is relevant for anaphoric purposes, as the pointing sign may be construed with an NP that was previously signed in that point. Lillo-Martin and Klima (1990) suggested that the loci established by pointing signs are realizations of the indices carried by NPs: signs carrying the same index must point to the same loci, while signs pointing to distinct loci carry distinct referential indices.⁸ From this point of view, the association of NPs with a position in the signing space is a reflex of a grammatical requirement: every NP must carry an index. What differentiates sign languages from spoken languages is simply that indices are overtly realized in the former.

Whether pointing signs should be assimilated to pronouns remains a controversial issue. Clearly, they serve a pronominal function, both anaphorically and deictically. Furthermore, in principle the three-way distinction between first, second, and third person pronouns might be extended to pointing signs, because the index finger in the direction of the signer indicates first person, the index finger in the direction of the addressee indicates second person, and the index finger in the direction of a point different from signer and addressee might be taken to express the grammatical category of “third person”. However, there are non-trivial differences between pointing signs and pronouns in spoken languages (see Friedman 1975; Meier 1990; Lillo-Martin & Klima 1991; Liddell 1995; Meir 2002; Meier & Lillo-Martin 2010, among others). For one thing, the realizations of non-first-person pronouns are potentially infinite, as they can have the superficial form of signs pointing to any position in the neutral space. Therefore, one can argue that the form of these pronouns cannot be specified in the lexicon. Second, the set of locations to which pronouns referring to the addressee point and the set of locations to which pronouns referring to neither the signer nor the addressee point may overlap, thus the form of the pronoun alone does not mark second person from third person. For this reason, Meier (1990) argued that only a first/non-first-person distinction is expressed by pointing in ASL (this analysis leaves the possibility open that other sign languages have a three-term deictic system).

The production of pointing signs by LISt signers is an obvious area in which variation in LIS is expected, since finger pointing gestures are not observed in congenitally blind children (or, at any rate, they are extremely rare) and these children use other kinds of deictic gestures like palm pointing (cf. Fraiberg 1977; Hewes 1981; Iverson et al. 2000). One explanation, suggested by Iverson et al. (2000) for this behavior of blind children is that referent location by forefinger pointing, but not by palm pointing, is obtained by crossing the imaginary line indicated by the forefinger with the imaginary line indicated by eye gaze (and possibly head orientation).⁹ As blind children cannot produce or perceive eye-gaze, they do not use finger pointing gestures.

Whether Deafblind signers avoid finger pointing signs to refer to a third person for similar reasons needs to be investigated. Surely, they cannot produce or perceive eye-gaze, but they might recover information about the locus based on the location and orientation of the hand, so the use of pointing signs might still be informative, although the relevant information might be harder to obtain than in presence of eye-gaze.

The only existing study on this topic is Quinto-Pozos (2002), who compared how Deaf sighted ASL signers and Deafblind tactile ASL signers differ with respect to a narrative task involving elicitation of pointing signs. The result showed that, unlike the Deaf sighted signers, Deafblind signers never produced third person pronouns, while in some case produced first and second person (singular) pronouns.¹⁰ Instead of using third person pronouns, they either finger-spelled the name of the referent or used nouns like MOTHER, FATHER, GIRL, or the Signed English sign SHE (not a forefinger pointing sign). Quinto-Pozos’ findings are consistent with the hypothesis that eye gaze is necessary to locate a point in the neutral space. Deafblind ASL signers can still finger point at themselves and the addressee, as this is presumably easier to do, because of proprioception and because they are in tactile contact with the addressee.

Our study shows a more nuanced picture, as LISt signers do produce pointing signs to refer to non-first/second person referents. However, these signs differ in two respects from the way they are articulated in LIS:

1. the hand configuration with the index finger is often substituted by a B, Ḃ, a bent B or a 5 configuration, as shown in Figure 9.

   

   Figure 9

   B, Ḃ, bent B and 5 configuration.

2. often, the hand does not point to the locus but it actually moves towards it. For example, as shown in Figures 10, 11, 12, to sign a first person pronoun the hand touches the signer, to sign a second person pronoun it touches the addressee, and to sign a third person pronoun it goes to the locus.

   

   Figure 10

   Reference to the signer (“First person pronoun”).

   

   Figure 11

   Reference to the addressee (“Second person pronoun”).

   

   Figure 12

   Reference to a person who is not present (“Third person pronoun”).

How are these differences between LIS and LISt related to the transition from the visual language to the tactile language? Two explanations can be adopted here. The first explanation is fully linguistic, while the second builds on what we know about haptic perception.

In nutshell, the linguistic explanation is that LISt signers move their hand to a locus (instead of pointing to it) in order to meet the grammatical condition that NPs should be able to be overtly assigned an index in a situation in which pointing becomes more difficult. If this hypothesis is right, this tells us something about the lively debate about whether the traditional first, second and third person distinction can be extended to pointing signs. If pointing signs were merely devices to introduce person distinctions, there would be an easy and efficient way to do so: palm pointing gestures, as we saw, are used by congenitally blind children. So, in principle, first, second and third person could be marked by using the direction of palm pointing: palm in the direction of the signer for first person, in the direction of the addressee for second person, and in any other direction for third person. However, Deafblind LISt signers choose to produce pointing signs by moving the hand to different points of the signing space. It seems plausible that they choose to do so because, at an abstract level, this is precisely how the pronominal system of LIS, their visual sign language, works: in the LIS pronominal system, pronouns are contrasted by being associated with different points of the signing space, and the changes LISt signers introduce with respect to pronouns are aimed at preserving this feature of their pronominal system. Another way to put it is that the pronominal system of LIS, and in general of visual sign languages, does more than (or perhaps something different from) introducing a distinction between first, second and third person: it marks the difference among speaker, addressee and other referents, but, at the same time, it provides a way of marking coreference.

A second way to make sense of the modifications in the production of pointing signs by Deafblind signers stems from studies about haptic perception. A preliminary caveat is necessary though. Studies of haptic perception by Deafblind signers are exceedingly rare, and hypotheses emerging from studies of haptic perception in the general population or even in blind individuals can be extended to deafblind signers only tentatively, as the extensive use of a tactile language might influence haptic perception (cf. Papagno et al. 2016). Having said that, there are findings in this literature that are potentially interesting for our issue (cf. Kappers & Bergmann Tiest 2016 for an overview). For example, under the experimental conditions described by Hollins & Kelley (1988), blind individuals and blindfolded sighted subjects were first requested to explore the position of objects on a table and then they were asked to recall these positions either by pointing to them or by placing objects again in the original positions. Blind individuals (but not blindfolded sighted subjects) were less accurate when they had to point. This introduces some analogies with our findings, since it seems that (deaf)blind individuals are better at reaching out a certain position than at indicating it from a distance. Another potential relevant finding is that, as observed by Pawluk et al. (2011), decoding haptic information (in the case at hand, distinguishing Figure from Ground) is more efficient if an object moves than if it stays still. So, the hand moving to the locus might offer bigger cues to the deafblind person who “receives” the pointing sign.

One possibility we would like to suggest is that these factors we considered as driving the modifications of pointing signs by Deafblind signers are both at work, namely that the innovative use of pointing signs by LISt signers is the result of a complex interplay of perceptual factors (a locus is haptically easier to detect if the hand moves there than if it points to it) as well as grammatical factors (the need to respect the requirement that indices be overtly expressed).

In the next Section we switch to a further case of linguistic innovation: the change from LIS to LISt that may be compared to processes that in spoken and in sign languages go under the label “grammaticalization”.

4.4 Cross-modal grammaticalization

In this Section we will show that an interrogative sign (WHAT) is used in LISt in contexts in which it cannot be used in LIS. We will show this by comparing the new LISt data to corpus of LIS, in which interrogatives have been annotated. We will argue that this innovative use is an example of cross-modal grammaticalization.

We start by introducing some background information on question formation in LIS. Polar questions (yes/no-questions) are distinguished from affirmative sentences in LIS (as in many other sign languages) only by an NMM which consists mainly in raised eyebrows:

As for wh-questions, LIS has a full set of wh-words: the signs WHO, WHAT, WHEN, WHERE, WHY, WHICH and HOW-MANY. The canonical position for these signs is at the right periphery of the sentence, no matter what grammatical function the wh-item plays. Thus, both the sign WHAT in (16), which is the object of the verb BUY, and the sign WHO in (17), which is the subject of the verb SIGN, appear in sentence final position. As indicated in the glosses below, wh-questions are also associated with a specific NMM (roughly, lowered eyebrows), which is obligatorily co-articulated with the wh-phrase. LIS signers tend to restrict the NMM to the wh-phrase (as in (16)–(17) below), although the NMM may also extend to a bigger portion of the clause, as explained by Cecchetto et al. (2009).¹¹

Structures like (18), in which a wh-phrase moves to the left periphery, are judged ungrammatical by our informants:

Let’s now turn to LISt. In the data we collected, we found three types of questions: wh-questions, polar questions, and alternative questions (the counterpart of an alternative question in English would be “Did John invite Mary or Paul?”). Since Deafblind signers cannot perceive facial expressions, and polar questions are distinguished from declarative sentences only by a facial NMM, one expects that, if LIS has an alternative way of signaling polar questions that does not require a facial NMM, Deafblind signers will make use of it. Indeed, questions in LIS may be introduced by signing the inflected form ₁ASK₂ (‘I ask you’) at the beginning of the sentence, as illustrated in Figure 13, and our Deafblind informants make use of this option in some cases (here, person inflection is realized by moving the sign ASK from the signer to the addressee).

Figure 13

₁ASK₂.

Collins & Petronio (1998) report that Deafblind signers of tactile ASL use a similar strategy to express polar questions. In ASL, polar questions may be signaled either by an NMM consisting of raised eyebrows, widening of the eyes, forward tilting of head and body, and possibly raised shoulders, or by a manual sign glossed as QUESTION which occurs at the end of the sentence and consists of a crooked index finger wiggling (this manual sign adds additional meaning in ASL, since it is emphatic). In tactile ASL, Deafblind signers form polar questions by using the manual sign QUESTION at the end of the sentence. The strategy of ASL tactile signers here is thus the same adopted by LISt signers when they use ₁ASK₂ sentence-initially to mark a polar question.

₁ASK₂, might be on a par with the NGT sign CALL which has been hypothesized to be a marker of direct speech by Bos (2016).

The use of ₁ASK₂, however, is not the only strategy LISt signers use in order to indicate interrogative force and in fact it is not the most interesting one for our purposes in this paper. To show how the other strategy works, let us focus on the use of the wh-sign WHAT in LISt. We found four different uses of WHAT:

1. the “canonical use” of WHAT,

2. the redundant use of WHAT,

3. the use of WHAT in alternative questions,

4. the use of WHAT in polar questions.

Below are some LISt examples illustrating each use (we follow the convention of using “/” to indicate the occurrence of a pause, the material in parentheses in (20) indicates the discourse preceding the example, finally we use the superscript “gesture” to indicate that what is being glossed is not a sign of LIS but a gesture):

In all these examples, WHAT is located at the right periphery of the clause, as in LIS. In (19) WHAT fulfills its standard role as an argument of the verb (the phonologically unrealized copula). In (20), WHAT is redundant: it does not fill the argument structure of the predicate NICE and the interrogative force of the utterance can already be inferred from the presence of the NP WHICH ANIMAL. Sentence (21) is an alternative question and, again, the function of WHAT is that of signaling interrogative force. The most interesting case for our current purposes is illustrated by sentence (22) and Figure 14, a polar question where WHAT is used to mark interrogative force.¹²

Figure 14

MUM SIGN WHAT.

Concerning the use of WHAT in (22), one natural question that arises is whether we are dealing with a sort of tag question. In this case, (22) would be made up by two clauses: the polar question MUM SIGN and an independent elliptical clause to which WHAT belongs. According to this hypothesis, (22) would have the structure in (23):

If this were the correct analysis, however, we should expect some prosodic cue to signal that WHAT belongs to a different clause in (22). However, no intonation break occurs and we could detect no other prosodic cue that might indicate a clause boundary. We then conclude that (22) is a mono-sentential polar question in which WHAT is a marker of interrogative force. Analogous uses of WHAT in LIS are non-existent. We investigated this by checking a LIS corpus collected in ten Italian cities during the years 2009–2010 (this corpus is described in Cardinaletti et al. 2011). The corpus consists of 165 hours of videos, of which 21 are dedicated to the question/answer task. As the latter part of the corpus is transcribed, we could inspect 7 hours of videos from 82 signers distributed over different cities and belonging to the same age group as our LISt informants for this task. In these videos, WHAT occurs in sentence final position in a number of cases that are not analyzable as canonical WHAT questions. For example, we found occurrences in alternative questions, exclamative uses of WHAT, and instances of WHAT doubling other wh-words like WHERE (see Geraci et al. 2015 for a more complete description). However, and most crucially, in over 7 hours of videos from 82 signers, we only found two occurrences of sentence final WHAT in constructions that, although of dubious interpretation, could be interpreted as polar questions (both occurrences were by the same signer from Salerno in Southern Italy). So, we conclude that there is no established use of WHAT as an interrogative marker for polar questions in LIS and that this is a genuine innovation introduced by LISt signers.

The use of WHAT in LISt polar questions is a robust phenomenon: when scanning the videos for the question task elicitation, out of the first 87 polar questions we encountered in the LISt corpus about a third (32.18%) contained WHAT at the right periphery. Interestingly, the LISt signer who is deafblind from birth was never exposed to LIS and yet she uses WHAT as a marker of interrogative force in polar questions. Here are some examples she produced, shown in Figure 15 (they were clearly polar questions, since she was playing a game in which she was trying to guess an object possessed by the addressee, and she accepted the answer “no” to both questions):¹³

Figure 15

ASK₂ IX₂ CAR WHAT.

Thus, our conclusion is that WHAT may be used as a marker of interrogative force in LISt: sentences (22), (24), (25) (and, perhaps, (21) as well) are plausibly analyzed in this way, since the only function of WHAT in these sentences is that of signaling that they are not declarative sentences.

It is important to realize that use of WHAT for this purpose, while it is unattested in LIS, is an instance of a linguistically attested strategy to express interrogative force. As is well-known, spoken languages have developed several ways to mark questions. In Italian, polar questions are formally distinguished from declarative sentences by intonation, while in English the same distinction is marked by word order (and intonation):

(26)	a.	Declarative in Italian
		Sei felice.
		‘You are happy.’
	b.	Question in Italian
		‘Are you happy?’
	c.	You are happy.
	d.	Are you happy?

In other languages, polar questions are derived from declarative sentences by adding an interrogative particle. An example of this strategy is provided by Tzotzil, a Mayan language spoken in Southeastern Mexico which is discussed by Konig & Siemund (2007).

In many languages, interrogative particles occur in wh-questions as well (see Dryer 2011 for the position of polar question particles in spoken languages and Zeshan 2011 for an overview on question particles in sign languages). Japanese is a well-known example. In (27) below (from Ishihara 2002) the clause final particle ‘no’ marks wh-questions:

In view of these observations, it is easier to make sense, from a linguistic standpoint, of the overuse of WHAT in LISt. The use of WHAT in polar question in LISt, unattested in LIS, can be naturally described by saying that WHAT in LISt is an interrogative particle. This is supported by the fact that polar question markers homonymous with the word corresponding to ‘what’ are cross-linguistically attested. For example, Bengali and Kannada, as discussed by Konig & Siemund (2007), are similar to LISt in this respect. Moreover, in LISt the use of WHAT as a particle to signal interrogative force extends to alternative questions and also to wh-questions, where it plays a redundant role.

Two further observations are in order. First, it should be stressed that the use of WHAT as an interrogative particle, while it originates from the need to compensate for the impossibility to perceive the facial NMM for polar questions, cannot be explained simply in terms of functional considerations. As we saw, LIS has an alternative way to signal interrogative force manually (₁ASK₂), and Deafblind LISt signers do exploit it. Moreover, from a purely functional point of view, sentence-initial positioning of the particle should be possible, and indeed preferable, since the addressee would have an early warning about sentence type. In fact, as we saw, WHAT, even when used as an interrogative particle, occurs at the right periphery of the sentence, as wh-items do in LIS. This indicates that the use of WHAT as an interrogative particle is grammatically ruled.

The second observation, already anticipated above, is that, when WHAT is used as a particle, it loses part of its lexical meaning (the meaning of the contentful word ‘what’) and serves as a grammatical indicator of interrogative force. In this sense, the use of WHAT is a case of grammaticalization. Grammaticalization is a well-attested diachronic process which is found in sign languages as well (cf. Pfau & Steinbach 2011). What is special about the case of WHAT is that it involves a cross-modal change, in which the shedding of lexical meaning occurs in the passage from a language in the visual modality to a language in the tactile modality. To the best of our knowledge, this is the first time that this phenomenon has been reported.

A natural question is whether the innovations we are talking about are the result of an explicit decision by the community of Deafblind signers or have been unconsciously developed by the members of this community through spontaneous interaction. We can answer this question. The members of this research team reported early finding about the use of WHAT in polar question to an assembly of Deafblind signers who wanted to be informed about the progress of our research (remember that our study began when “Comitato delle Persone Sordocieche” of Lega del Filo d’ Oro contacted us because they thought that a research on LISt at the academic level would benefit the status of their language). This meeting was organized by Lega del Filo d’Oro on May 8–9 2010 in Loreto (Central Italy), where about twenty Deafblind signers from different parts of Italy met. The five informants filmed for this study took part in the meeting and were initially surprised to be informed that they had been consistently using WHAT as an interrogative particle in polar question. So, they were not aware of the innovative grammatical strategies they had been using. However, after the 2010 Loreto meeting, which many LISt interpreters attended, this use of WHAT has entered the interpretation practice.