Relativization is a robust subordinating type across languages, displaying important typological variability concerning the position of the nominal head that the relative clause modifies, and sign languages are no exception. It has been widely assumed since Keenan & Comrie (1977) that the subject position is more accessible to relativization than object and oblique positions. The main aim of this paper is to investigate the extension of this famous generalization both across modalities (sign as opposed to spoken languages) and across relativization typologies (internally as opposed to externally headed relatives), and to verify how it interacts with age of first language exposure. We here report the results of a sentence-to-picture matching task assessing the comprehension of subject and object relative clauses (RCs) in three sign languages: French Sign Language (LSF), Catalan Sign Language (LSC), and Italian Sign Language (LIS). The results are that object RCs are never easier to comprehend than subject RCs. Remarkably, this is independent from the type of relative clause (internally or externally headed). As for the impact of age of exposure, we found that native signers outperform non-native signers and that a delay in language exposure emphasizes the subject/object asymmetry. Our results introduce a new potential diagnostic for LF movement: the existence of a Subject Advantage in comprehension can be used as a reliable and measurable cue for the existence of long-distance dependencies, including covert ones.

I would like to sincerely thank my supervisor Josep Quer for giving me the chance to work on Catalan Sign Language (LSC) in a very special place where I met amazing people and learnt new languages, among which Catalan became one of my favorites. I also want to thank him for the support and for always being available to look at new LSC data and discuss them together.

Who is a native signer? Since around 95% of deaf infants are born into a hearing family, deaf signers are exposed to a sign language at various moments of their life, and not only from birth. Moreover, the linguistic input they are exposed to is not always a fully fledged natural sign language. In this situation, is the notion of native signer as someone exposed to language from birth of any use? We review the results of the first large-scale cross-linguistic investigation on the effects of age of exposure to sign language. This research involved about 45 Deaf adult signers in each of three sign languages (Catalan Sign Language, French Sign Language, and Italian Sign Language). Across the three languages, participants were divided into three groups – those exposed from birth, those between 1 and 5 years of age, and those exposed between 6 and 15 years of age – and received a battery of tests designed for each language targeting various aspects of morphosyntactic competence. In particular, the tests focused on both those morphosyntactic phenomena that are known from the spoken language literature to be good detectors of language impairment or delay (i.e., wh-interrogatives and relative clauses) and on morphosyntactic phenomena that are sign language specific (i.e., role shift and directional verbs). The results showed a clear effect of being native, with significant differences across languages and tests between signers exposed to sign language from birth and those exposed in the 1st years of life. This confirms the life-long importance of language exposure from birth and the reliability of the notion of “nativeness”, at least for syntax. On the other hand, while in most domains the differences observed between populations might be differences in performance, for some specific constructions, signers belonging to the three groups may have different grammars. This latter finding challenges the generalized use of native signers’ grammar as the baseline for language description and language assessment.

Attitude role shift is a sign language strategy to report someone else’s utterance or thought. It has been analyzed either as a kind of demonstration or, alternatively, as a complex construction involving subordination plus a context-shifting operator. The present work reports the results of a sentence-to-picture matching task developed in three different sign languages (Italian Sign Language, French Sign Language and Catalan Sign Language) with the aim of providing experimental evidence about the nature of role shift. The task assessed the comprehension of indexical first-person pronouns in various syntactic contexts with and without role shift. We showed that constructions with role shift, which require context-shifting for the first-person pronoun, are never easier to comprehend than constructions without role shift that do not require context-shifting. In some cases, they are even more difficult. Additionally, we show that, in Italian Sign Language only, sentences in which the role shifted first-person pronoun is in object position are more difficult than sentences in which it is in subject position. We argue that this can be interpreted as an intervention effect and that this is an argument in favor of positing a context-shifting operator in the periphery of the role shift clause. Considering that the population of adult Deaf signers includes, besides native signers, a majority of individuals with a more or less severe delayed first language exposure, the second goal of this paper is to study the effects of age of exposure on comprehension of sentences with role shift. In the three languages under investigation, we found that native signers generally outperformed non-native signers in sentences with role shift and in subordinate clauses without role shift. This confirms that delayed language exposure has a lasting impact on adults’ comprehension of subordinate clauses of various degrees of complexity.

Among the existing sign language assessment tools, only a small number can be used in clinical settings. This contribution aims at presenting three comprehension assessment tests (two lexical and one syntactic) that offer a solid basis to build tools to assess language impairments in deaf signing adults. We provide the material and guidelines, based on psychometric analyses of the items, to make these tests suitable for clinical assessment. They are available for French Sign Language and Italian Sign Language. So far, the three tests were administered to three groups of deaf participants based on age of exposure (AoE) to sign language: native (AoE from birth), early (AoE = from 1 to 5 years), and late (AoE = from 6 to 15 years) signers. The results showed that the three tests are easy for the typical deaf signing population, and therefore, they can be adapted into tests that assess a deaf signing population with language impairments. Moreover, the results of the syntactic test reveal a categorial difference between native and non-native signers and therefore show the need for baselines that mirror the effect of AoE to sign language when assessing language competence, in particular in clinical assessment.