In this paper I aim at providing fresh evidence from Catalan Sign Language (LSC) to support semantic-pragmatic theories that treat contrast as a separate category in IS. Following Umbach (
The notion of contrast is controversial in the Information Structure (IS) field. Some theories assume that contrast is a feature of topic and focus (
In this research I understand contrast as the dependency relation between two or more contextually salient alternatives in discourse. The aim of the article is to provide empirical evidence from Catalan Sign Language (
The paper is structured as follows. Section 2 offers an overview on the existing literature on the notion of contrast in both spoken and sign languages (SLs). Section 3 states the methodology used for the elicitation of the data. Section 4 presents the paradigm of markers for different types of contrast. Section 5 analyses the interpretation of the different types of contrast in correlation with their prosodic markers. Section 6 offers a brief overview of some of the possible phonological, morphological, and semantic factors that can override the most frequent markers presented in Section 4. Section 7 summarizes the main conclusions.
Despite the considerable amount of literature that has been devoted to the notion of contrast, there is still controversy about how contrast should be defined. In the IS literature the notion of contrast has been mainly addressed from two different perspectives: syntactic and semantic. In syntactic analysis contrast is seen as a feature that can appear together with the topic or the focus of a sentence (
(1)
a.
Tegnap
Last
este
night
[Marinak]F
Mary.
muttatam
introduced.I
be
Pétert.
Peter.
‘It was to Mary that I introduced Peter last night.’
b.
Tegnap
Last
este
night
be
muttatam
introduced.I
Pétert
Peter.
[Marinak]F.
Mary.
‘Last night I introduced Peter to Mary.’
(
From this approach additive focus particles like ‘also’ or ‘even’ cannot combine with a CF, since a CF is interpreted exhaustively.
(2)
*Mari
Mary
[egy
a
kalapot]F
hat.
also
nézett
picked
ki
out
magának.
herself.
?‘It was also a hat that Mary picked for herself.’
(
However, this approach is problematic for languages where the marking of contrast is ambiguous, like English or German (
(3) | Raquel is a [linguist]F and/but |
From a semantic perspective contrast is understood as an independent category that is triggered by the existence of alternatives (cf.
The unifying approach of focus/contrast also poses some problems, though. Many languages, like Hungarian (see (1) above) and Finnish (4), have a specific marking for contrast (4b) which differs from the one for focus (4a), and thus they do not fit in a unifying approach.
(4)
a.
What things did Anna get for her birthday?
Anna sai [
‘Anna got flowers.’
b.
What is it that Anna got for her birthday?
[
‘Anna got flowers.’
(
In light of this, some works highlight the importance of separating new information from contrast (
The diversity of views presented here regarding the definition of contrast can be explained by the heterogeneous forms for expressing it in the different languages studied to date, which leads to different conceptions of this notion. While in some languages contrast is marked by grammatical means, in other languages contrast does not have an explicit marking. Therefore, it is not an easy task to come up with a unified theory that accounts for all languages studied until now (
SLs seem to contribute to the view of contrast as an independent notion, since they share some common features for the expression of contrast: most of the SLs studied to date show specific marking that only appears when contrast is present, and it is clearly distinguished from the marking of other IS notions, such as topic and focus (§ 2.3). In LSC contrast also shows clear independent prosodic marking that can be distinguished from the marking of focus and/or topic (§ 4) and correlates with different interpretations associated to different types of contrast (§ 5). However, it does not show a specific syntactic position for CF associated to exhaustivity. For this reason, I adopt a semantic-pragmatic perspective that allows us to better explain the expression of different types of contrast in LSC and the correlation between prosodic markers and pragmatic interpretations.
As mentioned in the previous section, some theories have developed more fine-grained analyses that present contrast as an independent notion that can be found in information and discourse structure and that involves different types (cf.
Through crosslinguistic comparison, Molnár (
(
At the pragmatic level, Molnár distinguishes
At the semantic level, two types of contrast are connected to open sets of alternatives:
Umbach (
(5) | John bought the |
( |
As for contrast due to exclusion, it can be further divided into two varieties with semantic differences. The first variety is exemplified in (6) below, where the contrastive focus
(6) | (A: Mary made the salad and Anna the hamburgers.) |
B: |
|
(adapted from |
(7) | (A: Tonight, Ronald and Rosa went shopping.) |
B: Tonight, only |
|
(adapted from |
Both varieties of contrast due to exclusion are exemplified only via the pragmatic context of a correction in Umbach’s work; however, as will be shown in § 5 this type of context could also be found in the context of a selection between two alternatives (selective contrast) in LSC, since the same ‘exclusive’ meaning could be derived.
At the DS level, Umbach analyses the discourse relations
(8) | a. | In Paris, Ronald only went to the |
b. | In Paris, Ronald went to the |
(9) | a. | (A: Yesterday, Ronald went to the opera.) |
B: Ronald went to the |
||
b. | Yesterday, Ronald did not go to the |
|
( |
Both discourse relations behave similarly to contrast at the IS level and seem to be intertwined with contrast due to exclusion: both require the similarity plus dissimilarity condition and both indicate the exclusion of one of the alternatives; however,
Similarly to Umbach, Repp (
(10) | [Peter]C1 went to [Rome]C2 but [Marc]C1 went to [London]C2. |
(11) | John, Pete and Josie all offered help. I will ask [John]F. |
(12) | John was choosing fruit for his new bowl. He picked [a banana]F. |
Regarding discourse relations contrast may involve different degrees of contrastiveness that may be categorized into different discourse relations: i) Smooth discourses (
In many studies, the so-called
Regarding their marking, contrast types are often marked by (morpho)syntactic and/or prosodic strategies. Repp (
In general, IS notions tend to occupy positions of prosodic prominence in the sentence; however, there is no one-to-one correlation between prosodic markers and IS notions. Prosodic marking is considered just a tendency, since these notions can also be left unmarked or they can be marked by different means (
Navarrete-González (
However, the following questions are still open: are these common NMMs marking contrast at the level of alternatives or at the DS level? Are additional markers used to express different degrees of contrast? Moreover, do these prosodic markers appear just as tendencies that can be overridden by other factors? Sections 4, 5 and 6 intend to shed some light on these questions, taking as a basis the categorizations sketched above.
Studies conducted until now in SLs have generally assumed that contrast is not an independent category in IS but a feature of focus and topic (cf.
IS notions in SLs may be marked by syntactic or prosodic means (
(13)
‘What Lee painted was the chair.’
(
Kimmelman (
(14) | [ |
[NGT] |
‘[No,] the woman eats ice-cream.’ |
(15) | [ |
[ |
‘[No,] the boy eats candy.’ |
As for the prosodic strategies, SLs express intonation primarily through non-manual markers; namely, facial expressions, and body and head movements (
Almost all SLs studied to date have shown that body leans are the most common strategy employed by SLs for the expression of contrast between two referents. In ASL, forward and backward body leans are consistently used for expressing contrastive relations (
(16)
‘No, not my friend, it’s my brother [who is learning ASL]
(
In ASL and NGT, besides expressing contrast, forward leans are associated with inclusion and affirmation, and backward leans with exclusion and negation at the lexical level and beyond (
Scale of inclusiveness and exclusiveness in ASL (
In NGT and RSL body leans are usually accompanied by the use of the opposite sides of signing space for placing contrasted referents, as illustrated in example (17) from RSL.
(17)
[
‘The cat bites a boy. The dog bites a girl.’
(adapted from
It is important to notice that the marking of contrast described above is spreading over both topics and foci in many examples, like (17) above. Kimmelman (
Crasborn & Van der Kooij (
Summary of the main findings on the marking of contrast for SLs.
SL | Type of data | Type of description and/or analysis | CF markers |
---|---|---|---|
ASL | Elicited | Syntactic, pragmatic | Wh-clefts, eyebrow raise, forward leans |
NGT | Experimental and corpus | Prosodic, syntactic, pragmatic | Left-right body leans, opposite sides of space, head forward |
RSL | Experimental and corpus | Prosodic, syntactic | Left-right body leans, opposite sides of space, head forward |
LSF | Elicited | Semantic | Eyebrow raise, head nods, Forward/backward leans |
In sum, there seem to be evidence that SLs mark contrast independently from other IS notions. SLs can be argued to provide evidence that we are actually dealing with a different IS notion expressed by specific grammatical means, which overlaps with the topic and the focus of the sentence. The traditional approach adopted until now in most SL research has successfully served the purpose of providing the first descriptions of the expression of IS notions in SLs. However, most of them have consistently assumed traditional definitions for IS notions without questioning more theoretical issues like the ones posed in § 2.1 and § 2.2. This paper analyses in greater detail semantic-pragmatic interpretations of different types of contrast and their grammatical reflexes in order to contribute to a better understanding of the nature of this notion in both SLs and spoken languages. I adopt a semantic-pragmatic approach, since it allows us to broaden the paradigm of contrast markers in LSC. The definitions of IS notions in this perspective explain better the phenomena found in our data, allowing us to provide a more thorough explanation of the semantic features found in each type expressed through additional markers (head movements).
The data analysed in this paper has been collected through a combination of different methods, taking into account Matthewson’s (
Most of the data have been obtained from two deaf native signers, a woman and a man, raised in Catalonia and educated in special schools for the deaf, where LSC was the main language of communication among deaf students. Different types of elicitation tasks were conducted: i) picture elicitation tasks, ii) storyboard and story-telling tasks (monologues and dialogues), iii) translations, and iv) felicity judgments. Naturalistic data was also obtained from three signers from corpus observation to compare and validate results.
30 sentences were elicited using visual stimuli from the
Picture from the
Questions were designed to trigger different types of answers: i) some questions were seeking for plain information (‘What are the woman and the man doing?’), ii) some questions were forcing the signer to select between two alternatives that were included in the question (‘What is the woman riding: a horse or a bike?’), and iii) some questions contained false information that the signer needed to confirm or refute (‘The man is riding a bike, right?’). These different types of questions were thought to elicit minimal pairs between parallel, selective, and corrective contrast respectively.
The goal of these tasks was to obtain more naturalistic data in the context of a monologue or a dialogue. Two storyboards from Totemfield Storyboards (
Moreover, two monologues were recorded in which signers had to retell two mute short films (
Signers were asked to translate a sentence that was presented in written Spanish.
(18) | Context: Your friend asks you what Mary ate. You tell her: |
‘Mary ate a salad and a burger.’ |
(19) | Context: Your friend is not sure if it was a pizza or a burger what Mary ate. You know it was a pizza, so you tell her: |
‘Mary ate a pizza.’ |
(20) | Context: Your friend says that Mary ate a pizza but you know it is not true, so you tell her: |
‘Mary didn’t eat a pizza but a burger.’ |
All data collected was rated by the informants weeks later to ensure consistency in the results. Each piece of data was presented again with a signed context, and participants had to rate the felicity of the sentences in relation to that context in a binary way: felicitous vs. infelicitous. No descriptive statistics were conducted.
Finally, 20 sentences were collected from the Catalan Sign Language corpus (under development in the
As mentioned in § 2, most of the studies on IS notions in SLs have assumed that contrast is not an independent category, but a feature that appears in some types of focus and topic constituents. Following Vallduví & Vilkuna (
Focus in LSC can be expressed syntactically, through a change in the basic word order (SOV) as in (21) (
(21) | |
‘(I) |
(22) | |
‘(I) eat |
|
( |
Topic in LSC is typically placed in sentence initial position and marked with eyebrow raise and an intonational break after the topicalized constituent (
(23)
[
‘Onions, I hate.’
(
In line with previous research on contrast in SLs (cf.
(24)
[
‘Giorgia is a linguist and/but Raquel is an interpreter.’
In the example above, the topic and the focus of the contrasted sentences maintain their own markers, which overlap with the contrast markers described before. The topics
Until now we have seen that contrast in LSC has been claimed to be expressed with this combination of markers, which overlap with other IS notions: topic and focus. However, is it always the case that these markers express a contrastive interpretation? Is there a one-to-one correlation between this combination of markers and the interpretation of contrast?
Mayol & Barberà (
In the next subsections I provide a paradigm of different types of contrast identified in LSC, and the different strategies that signers use to express this notion. I compare the markers of each of the types, and analyse the semantic interpretations triggered by each type and their correlation with some markers. Finally, I propose a classification of different types of restrictions that can affect (and change) the realization of these markers, giving rise to other marking strategies for the expression of contrast.
In LSC at least three different types of contrast can be identified: i)
Parallel contrast introduces parallel alternatives that belong to the same set of alternatives, either symmetric or asymmetric. The most common strategy for the expression of parallel contrast is the combination of different prosodic and morphophonological markers: body leans and head tilts from left to right, and the use of the opposite sides of signing space (
Parallel contrast markers.
(25)
[
‘Raquel is an interpreter and a linguist.’
(26)
[
‘Giorgia is a linguist and/but Raquel is an interpreter.’
Another strategy commonly used in LSC for the expression of this type of contrast is the lexical marker
Sign
(27) | ‘What did you buy at the supermarket?’ |
‘Potatoes, eggplants, tomatoes, fish, meat, and other things.’ |
Even though this marking strategy is preferred in these contexts, this sign is optional. In the absence of this marker the same content is expressed through left-right body leans and the use of the opposite sides of signing space, as shown in (28).
(28)
‘What did you buy at the supermarket?’
‘Potatoes, eggplants, tomatoes, fish, meat, and other things.’
Sometimes parallel contrast may be expressed through a strategy called dominance reversal (cf.
(29)
Context: The other day I saw a fight in the Street. There were two men arguing and in the end…
dh:
ndh:
‘They fought and one of them punched and slapped the other.’
Unlike what has been claimed for NGT (
Finally, in this type of contrast the use of additive/scalar focus particles like ‘also’ and ‘even’ is common in LSC. In (30) and (31) below the same combination of NMMs is again displayed over the contrasted focussed items.
(30)
[
‘Raquel is an interpreter and also a linguist.’
(31)
‘[You can consult] the law in English and also in Catalan.’
Mayol & Barberà (
(32)
‘The deer was running very fast with the boy lying on his head. Even the dog was running very fast.’
(
In our data, the meaning of ‘even’ can also be expressed through different lexical signs that are uttered in combination with NMMs similar to the ones described by Mayol & Barberà (
(33)
Context: You organised a party. You invited your group of friends, but you didn’t expect Anna to come, since she never goes to parties.
a.
b.
c.
‘The party was so successful. Even Anna showed up!’
In Section 5 I suggest that head thrust is connected to unexpectedness, not only in this type of contrast (parallel) but also in corrective contrast (cf. § 4.2.3).
Selective contrast is defined here as the type of contrast that provides an alternative selected from a set of two or more overt alternatives that were previously introduced in the discourse (cf.
(34)
What is the woman doing: riding a bike or riding a horse?
‘Riding a bike.’
Selection may be also expressed through other syntactic strategies like fronting or clefting. In (35a) the selected alternative is fronted, and again a repeated head nod is found in the selected alternative. In (35b) the signer uses the same strategy fronting the selected alternative. In this sentence, though, the sign
(35)
C
a.
‘PIZZA, Mary ate.’
b.
‘It was a PIZZA that Mary ate.’
In examples (35a-b) no body leans from left to right are displayed since the structures (fronting and clefting) are serving the purpose of contrasting the referents. One possible explanation is that only one of the conjuncts is expressed and therefore there is no need to perform these markers. In (34) the basic word order is preserved so this marking is added to highlight the alternative selected.
Corrective contrast substitutes an alternative that is considered false by the interlocutor. Again, the most frequent strategy for expressing this type of contrast in LSC is the combination of body leans and/or head tilts from left to right and the use of the opposite sides of space in combination with a head movement: a strong head thrust that emphasize the correct alternative (36).
(36)
‘Mary didn’t eat a pizza, but a burger.’
Interestingly, unlike examples (35a–b) above, and contrary to what Kimmelman (
(37)
A: ‘The sea is yellow.’
B:
‘No, the sea is BLUE.’
In LSC forward-backward body leans can be found in combination with left-right body leans (cf.
(38)
‘Mary didn’t eat only pizza, (she ate) pizza, ice cream and salad.’
In sum, all types of contrast are expressed with the same combination of markers: body leans and/or head tilts from left to right in combination with the use of the opposite sides of signing space. However, in selective contrast and corrective contrast (and also in some examples of parallel contrast with ‘even’), additional head movements are found, which trigger additional interpretations that will be further explained in the next section.
Each of the contrast types described in Section 4 share a basic meaning: they all involve contrast due to similarity plus dissimilarity. However, we can distinguish different types of contrast in which additional pragmatic interpretations are triggered by some NMMs (head nods and head thrusts). Based on Umbach (
The additional head nod is triggering an exhaustive reading in selective contrast; and the additional head thrust is triggering an exhaustive and counterexpectational reading in corrective contrast. Mayol & Barberà (
Moreover, repeated head nods have been attested to be co-articulated with signs to express the positive polarity of a clause. Thus, this NMM has also been connected to verum focus in other SLs (cf.
Regarding the perception of the prosody in these constructions, it seems that the additional head markers in both selective and corrective contrast result in a stronger or more intense prosody in more contrastively marked contexts (
Prosodic marking of the different types of contrast.
Moreover, all contrast types share a common feature: they involve semantic parallelism between the elements being contrasted in the sentence (contrast due to similarity plus dissimilarity in Umbach’s terms). I understand by semantic parallelism the fact that the contrasted alternatives belong to the same set and are semantically comparable to each other. It can be the case that two alternatives do not involve syntactic parallelism, but they can be semantically parallel. Semantic parallelism between alternatives in LSC is expressed by the basic combination of markers that is repeated in each of the contrast types presented before (parallel, selective and corrective).
All in all, contrast types seem to be built compositionally, since there are additional meanings that combine to form different discourse relations (selection and correction) expressed though different combinations of markers. However, other prosodic features seem to be perceived as gradient: the movement of a head thrust is articulated with more tension in the neck muscles than the repeated head nod, and this tension seems to be adding intensity to the contrasted alternative.
In previous sections the paradigm of LSC markers for three different types of contrast was presented. I established that the common marking for any type of contrast in LSC is a combination of left-right body leans and/or head tilts plus the use of the opposite sides of signing space. Even though a high percentage of the data elicited was marked with this combination of markers, some counterexamples were elicited that made me reflect on the possible factors that could override these markers. Quer (
In this section, I try to elucidate if prosody in LSC has a limited amount of strategies in some contexts, which could trigger the modification of the markers for contrast. I analyse whether in LSC prosodic markers of contrast could be partially or completely modified due to other predominating factors. Moreover, I describe alternative strategies that signers use in order to express contrast when these clashes arise. Restrictions are categorized into three different types: phonological, morphological, and semantic.
In LSC some signs are uttered anchored to a location on the body of the signer. In these cases there is a phonological impossibility to use space in front of the signer. Therefore, contrast cannot be expressed through the use of the opposite sides of signing space in the strict sense. The result is that the combination of markers established for contrast is reduced to left-right body leans and/or head tilts, which are directed towards locations in space in an abstract way (39).
(39)
‘Gemma went to Paris and Raquel to New York.’
In example (39) above,
NMMs in LSC are not only used for the expression of intonation. They can also have other grammatical functions, such as morphological and syntactic functions (
Space in SLs is used for the expression of many different grammatical functions (
(40)
Context: The other day I saw a fight in the street. There were two men arguing and in the end…
dh:
ndh:
‘They fought and one of them punched and slapped the other.’
Dominance reversal has been already described for other SLs such as RSL and NGT (cf.
In LSC time is conceptualized in a timeline that starts behind the shoulder of the signer and spreads over the front part of the signer. The past is conceptualized either behind or at the shoulder (depending on how far in time the action is), and the future is conceptualized in front of the signer (
(41)
‘I didn’t finish the BA this year, it was in the past. This year I finished the MA.’
Example (41), however, is misleading, since in some other examples involving contrast and time relations this restriction seems not to be a problem for the expression of left-right body leans. In (42), for instance, left-right body leans express the contrast between the two conjuncts as expected, and a backward body lean spreads over
(42)
‘Last year I went on holidays to the Canary Islands. This year I’ll stay in Badalona.’
The difference between examples (41) and (42) is that (41) is a correction, and (42) is an example of parallel contrast. The forward-backward body lean in (41) thus might be expressing denial and affirmation (as predicted by
Some lexical specifications of the signs of a sign language may be determined by the semantics of a verb or a noun. For instance, lexically specified body movements are attested in signs that involve a semantics of inclusion or exclusion. In different SLs, forward body leans have been associated with inclusion and affirmation, while backward leans have been associated with exclusion and negation (cf.
I took these claims as a baseline to test if LSC follows the same patterns, and the lexical level specifications affect or change the markers of contrast that work at a suprasegmental level. In example (43) below, the sign
(43)
Context: You had an argument with the president of the Sports Committee of your Deaf association, and you decided that you won’t participate in the organization of the activities anymore. You tell your friend so.
‘Until now, I had always participated in the (organization of the) different activities. Now I stopped participating.
We would expect that these specific lexical semantic features of inclusion and exclusion might influence the realization of the contrasted signs, which we would expect to be uttered with forward and backward body leans instead of left and right body leans (or at least with a combination of both). Surprisingly, the signs
In sum, out of the three different contexts that were tested, only phonological and morphological restrictions seem to affect or modify the combination of markers found for the expression of contrast in LSC.
In this paper I have described and analysed the notion of contrast in LSC. I have shown through empirical evidence that contrast is most of the times expressed through left and right body leans and/or head tilts and the use of the opposite sides of signing space. Moreover, I have categorized the notion of contrast into three different types: parallel, selective and corrective contrast. All types happen to share the same combination of markers plus some additional head movements in selective and corrective contrast (and in some instances of parallel implicit contrast with ‘even’), which trigger additional pragmatic interpretations: exhaustivity and counterexpectations. I have also shown some syntactic strategies –fronting and clefting– that are used in some specific contrast types.
Moreover, this research has shown that even though LSC has preferences for expressing contrast in a specific way there are some phonological and morphological factors that can affect this marking, giving rise to alternative strategies.
Finally, contrast seems gradient at the prosodic level, since the additional head movements found in some types of contrast add intensity to the prosody, which is perceived as stronger by the interlocutor. On the other side, contrast discourse relations are built compositionally, since different interpretations such as exclusion, exhaustivity and counterexpectations are combined on top of a basic condition (similarity plus dissimilarity) to form more complex pragmatic discourse relations.
The results of this research contribute to a better understanding of IS notions in LSC, and also crosslinguistically in both spoken and sign languages. The fact that in LSC the marking of contrast is the same for topics and foci provides empirical support for theories that consider contrast as an independent category orthogonal to topic and focus.
ASL = American Sign Language, CF = contrastive focus, CT = contrastive topic, DGS = German Sign Language, IF = information focus, IS = information structure, LSC = Catalan Sign Language, LSF = French Sign Language, NGT = Sign Language of the Netherlands, NMM = non-manual marker, NP = noun phrase, QUD = question under discussion, RSL = Russian Sign Language, SL = sign language
The usual glossing conventions in the sign language literature are followed, according to which manual signs are represented by the capitalized word corresponding to the gloss of the sign (the most general translation into a spoken language word). The scope of nonmanual markings is represented with a line that spreads over the manual material with which it is co-articulated. The relevant abbreviations for the purposes of this paper are the following ones: dh (dominant hand); ndh (non-dominant hand); ix (pointing sign); IX# (pronominal index; the number corresponds to 1st, 2nd or 3rd person); rhq (rhetorical question); re (raised eyebrows); bl (body lean); hs (head shake); ht (head tilt); hn (head nod); hthr (head thrust); mth (mouthing); we (wide eyes); sp (space).
The idea behind the QUD is that each sentence in discourse addresses or answers a question, which is often implicit (for further details see
Narrow focus here is understood as involving only one constituent in the sentence (subject, object or verb). It contrasts with broad focus that involves a VP or a whole sentence.
These constructions have been claimed to be the equivalent to wh-clefts by Wilbur (
This elicitation task was based on the methodology and classification used in Kimmelman (
Both participants are proficient in Spanish.
For the scope of this paper I will only be considering narrow focus.
Less frequently, topic can also be found in other positions, but this issue is beyond the scope of this paper.
Further research regarding focus particles is needed in order to clarify the differences between the lexical signs used in the expression of ‘even’ in combination with NMMs, but our hypothesis is that they trigger different degrees of scalarity.
Further research is needed to clarify how clefts are expressed in LSC.
Manual markers, such as duration of the sign, and repetition of the movement, also contribute to this gradient perception adding a more intense stress in more contrastively marked contexts, like correction (cf.
Thanks to Fabian Bross for bringing up this example.
I would like to acknowledge my informants, Delfina Aliaga and Santiago Frigola, for the recordings and elicitation sessions about this topic and for sharing with me their language. Thanks also to Dr. Gemma Barberà and Dr. Josep Quer for their suggestions on preliminary versions of this paper and to the anonymous reviewers and the editors for their comments, which have been crucial for the improvement of this article.
This contribution has been possible thanks to the SIGN-HUB project, which has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 693349, to the Spanish Ministry of Economy and Competitiveness and FEDER Funds (FFI2015-68594- P), and to the Government of the Generalitat de Catalunya (2014 SGR 698).
The author has no competing interests to declare.