Spoken and sign language

Comparative studies of the mental lexicon between spoken and sign language are scarce. Marschark et al. (Reference Marschark, Convertino, McEvoy and Masteller2004) studied the organization and use of the mental lexicon in Deaf and hearing speakers using a single-response free association task. Their results indicated a general similarity in the organization of lexical knowledge in both groups, with stronger associations between category names and exemplars for hearing speakers. Mann & Marshall (Reference Mann and Marshall2012) conducted a repeated free association task with American Sign Language (ASL) Deaf children and hearing English children. Their results showed similar patterns in the responses of Deaf subjects and monolingual English-hearing subjects. For the authors, these results suggest that language development in sign and spoken languages is governed by similar learning mechanisms, based on the development of semantic networks.

Dong and Li (Reference Dong and Li2015) indicate that bilinguals of two spoken languages tend to integrate conceptual differences between translation equivalents. However, the authors find that bilinguals display a tendency to maintain the L1 conceptual system for L1 words and to adopt the L2 conceptual system with L2 words. Additionally, the authors found that at the very early learning stageFootnote ¹ of an L2 word, L2 learners are more dependent on their L1: learning an L2 is a process of integrating conceptual differences in two languages. Then if a specific Deaf-signing population remains in an early learning stage of a spoken language such as Spanish, it might be expected that the aforementioned conceptual integration is far from being.

To characterize the notion of linguistic modality (limited in our case to the sign vs. spoken contrast) in its different aspects, below we will discuss some semiotic, linguistic, psycholinguistic, and sociolinguistic differences and similarities between sign and spoken languages that can discriminate between the mental lexicon of Deaf signers and hearing speakers. In this study, the notion of language modality does not preclude the suggestion of the multimodality approach (i.e., McNeil, Reference McNeil1979; Perniss, Reference Perniss2018; Perniss & Vigliocco, Reference Perniss and Vigliocco2014). This approach considers language an integrated system with gesture and speech as components. In the following lines, when we compared language modalities, we refer to the grammar-lexical component based on conventionalized gestures for sign languages and vocalized sounds for spoken ones. It is not our aim to be exhaustive in each aspect, but only to highlight in each one some points that we understand to be of interest to the mental lexicon and its processing.

Iconicity

Within semiotic aspects, although there is a substantial number of arbitrary lexical items in sign languages, the literature considers a greater pervasiveness of iconic lexical items in sign languages than in spoken ones (Cuxac & Sallandre, Reference Cuxac, Sallandre, Pizzuto, Pietrandrea and Simone2007; Klima & Bellugi, Reference Klima and Bellugi1979; Taub, Reference Taub2001; Wilcox, Reference Wilcox2000. For a review, Perniss et al., Reference Perniss, Thompson and Vigliocco2010). Wilcox (Reference Wilcox2000, p. 123) describes iconicity as a resemblance relation between two construals: one of the real-world scenes and the other of the form of the objects of reference. The aforementioned resemblance can be understood as a structure mapping (Gentner, Reference Gentner1983; Gentner & Markman, Reference Gentner and Markman1997) because iconic items imply a comparison process between a semantic representation (i.e., past meaning) and a visual (i.e., moving hand over the shoulder front to back) or acoustic (i.e., use the word “behind” in expressions such as “The past left behind”) representation of a linguistic form (Emmorey, Reference Emmorey2014). The literature recognizes some types and degrees of iconicity in sign languages (i.e., pantomimic and perceptual) with alternative mechanisms such as indicating the shape, the size, or the proximity of the referent (Dingemanse et al. Reference Dingemanse, Blasi, Lupyan, Christiansen and Monaghan2015).

Another alternative is to classify the iconicity in line with the pattern of similarity matching between an aspect of form and one of meaning. Such an approach differentiates between absolute and partial iconicity. Onomatopoeia is a case of the former and the so-called diagrammatic iconicity is a case of the latter. Diagrams offer a semantic structural correspondence between form and meaning (Dingemanse et al. Reference Dingemanse, Blasi, Lupyan, Christiansen and Monaghan2015). Padden et al. (Reference Padden, Meir, Hwang, Lepic, Seegers and Sampson2013) aimed to describe the iconicity as a shared property among groups of signs (pattern iconicity). Finally, Ortega et al. (Reference Ortega, Sümer and Özyürek2017) indicate that at the lexical level “… signs exploit a wide range of iconic depicting strategies to represent the same referent …”. Several of these strategies involve an object and the manipulation of it (i.e., handling), outlining its shape (i.e., shaping), or using a body part to represent it (i.e., instrument).

In contrast to spoken languages, the sublexical iconicity of sign languages has its potential in that the phonological pole of the signs is formed by components of the human body spatially exposed to the interlocutors (hands, torso, face, and head). This iconicity is relative to the referents involving the body motricity (the ability to move or use one’s muscles to produce movement. It is the capacity to control and coordinate the movement of one’s body and limbs) associated with actions, emotions, or the perception of concrete objects, and their eventual use as a basis for providing meanings to lexical pieces by some mapping mechanisms such as metaphors or metonymies. Furthermore, although iconicity is not absent in spoken language (Dingemanse et al., Reference Dingemanse, Blasi, Lupyan, Christiansen and Monaghan2015; Perniss et al., Reference Perniss, Thompson and Vigliocco2010), it relies mostly on internal components of the human body, not exposed to interlocutors (i.e., larynx, tongue, alveoli, etc.). Furthermore, imaginability, that is, the ease of imagining the meaning of a word (partly due to its iconicity), is a property of words/signs that correlates with the abstraction (Kousta et al., Reference Kousta, Vigliocco, Vinson, Andrews and Del Campo2011).

As suggested by Rodriguez-Cuadrado et al. (Reference Rodríguez-Cuadrado, Ojedo, Vicente-Conesa, Romero-Rivas, Sampedro and Santiago2022), iconicity relies on concreteness. The referents of concrete concepts are accessible as sensorimotor information (i.e., seen, heard), and it is possible to interact with them (see Borghi et al. (Reference Borghi, Binkofski, Castelfranchi, Cimatti, Scorolli and Tummolini2017). Speakers can use the physical appearance of these referents to guide the formation of iconic items. We share the theoretical approach (Lakoff & Johnson, Reference Lakoff and Johnson1980) that argues that the human mind gets grounded in concrete concepts and includes regular mechanisms such as conceptual metaphor and metonymy. For this approach, items for abstract concepts can become iconic to the physical appearance of those referents. Concerning the vocabulary of sign languages, this approach affords the distinction between iconic and arbitrary signs for abstract concepts (Taub, Reference Taub2001; Wilcox, Reference Wilcox2000).

A fundamental difference is that signs are better at iconically representing the concepts they denote and have their symbolic matter in space (Taub, Reference Taub2001). This is due to the high potential for semantic access based on the spatial substrate of signs and the analogy of signs with relevant sensorimotor information. Manhardt et al. (Reference Manhardt, Ozyurek, Sumer, Mulder, Karadöller and Brouwer2020) found visual attentional differences between “thinking for speaking” from “thinking for signing” during message preparation. They suggested that iconicity can mediate the link between language and human experience and guides signers’ but not speakers’ attention to visual aspects of the world. Despite the aforementioned pervasive iconicity in sign languages, Hohenberger and Leuninger (Reference Hohenberger, Leuninger, Pfau, Steinbach and Bencie2012, p. 718) point out that there is no difference in the processing of iconic and non-iconic signs between spoken and sign languages. For instance, iconicity plays no role in lexical retrieval. However, Ortega and Morgan (Reference Ortega and Morgan2015), studying the sensitization of iconic signs in the mental lexicon of hearing adults, suggested that this population (hearing speakers who do not sign) process iconic signs in the manner of gestures. Signers, on the other hand, use a different mechanism to process iconic signs. Authors such as Sehyr and Emmorey (Reference Sehyr and Emmorey2019) found that the perception of the mapping between form and meaning in ASL depends on linguistic knowledge and task. The effort to create linguistic models not based on vocal language tools, categories, terminology, and analyses has a large trajectory. Throughout most of the twentieth century, different models proposed to describe sign languages were based on a hierarchy: only the lexical units (i.e., standardized in form and meaning signs) were considered at the core of the language, while the “productive signs” (i.e., iconic constructions) were pushed to the linguistic borderline, closer to the level of gesticulation and mime (Capirci et al., Reference Capirci, Bonsignori and Di Renzo2022).

In the last decades, some scholars (i.e., Cuxac, Reference Cuxac1999; Capirci et al., Reference Capirci, Bonsignori and Di Renzo2022; Wilcox & Occhino, Reference Wilcox and Occhino2016) found in Piercian semiotics and Cognitive Linguistics theoretical frames for overcoming the hierarchical approach to language modeling. Finally, Capirci et al. (Reference Capirci, Bonsignori and Di Renzo2022) suggest a model in which signs’ different iconic, symbolic, and indexical features are detectable in the single linguistic sign. For them, the dominance of the feature will determine the different use of the linguistic unit.

Signs and lexemes

Within linguistic aspects, Johnston and Schembri (Reference Johnston and Schembri1999, p. 126) distinguish between signs and lexemes. For these authors, the latter are fully conventionalized pieces and can be stored as a lexicon of a language. The following paragraphs present some research on classifiers in sign languages as they may affect vocabulary and mental lexicon across linguistic modalities. The difference between a lexicalized sign and one with a classifier is that the latter responds to the discursive domain. That is, for example, a verb with a classifier such as “to walk” is not lexicalized in the Uruguayan Sign Language (LSU). The classifier allows the signer to modify this sign to the point of adapting the predication of the verb WALKING to the discursive interest. The signer can point with the sign to walk forward or to turn the corner to the left or the right. Schembri (Reference Schembri2003, p. 18) shows a number of difficulties in finding a description of classifiers that can be transversal between spoken and sign languages. What is relevant to the phenomenon of classifiers for this study is their presence in both linguistic modalities, the differences in the way that they operate (i.e., usually for nominals and noun phrases in the spoken language, but for verbs and verb phrases in sign language), their strong relation with discourse, the difficulties and lack of consensus in finding definitions that might satisfy what happens in both modalities and the closed character of these pieces.

For example, in Spanish, to quantify a noun such as “ganado” (Cattle), it is necessary to use a classifier that links the numeral to the noun. In this case, “cabezas de” (heads of) is a classifier between the lexical items “Tres” (Three) and “Ganado” (Cattle). The phrase “Tres ganado” (three cattle) is ungrammatical. A classifier is needed for the count of the nominal (Cattle). In sign languages, as in some Asian spoken languages such as Chinese Mandarin, classifiers are more standard (i.e., 棵 kē is a tree’s classifier). It means that the same classifiers can be used for different nouns.

For sign languages, Zwitserlood (Reference Zwitserlood, Pfau, Steinbach and Bencie2012, p. 158) described the classifiers as “… morphemes with no-specific meaning which are expressed by particular configurations of the manual articulator and which represent entities by denoting salient characteristics…”. The status of classifiers as lexical items is controversial and there are different approaches to them (see Emmorey, Reference Emmorey2003). Furthermore, studies on errors in German Sign Language (DGS) production (Leuninger et al., Reference Leuninger, Hohenberger, Waleschkowski, Carson Schütze and Ferreira2007) suggest that the bipartition of the mental lexicon into a lemma and a lexeme component seems to be valid for both language modalities (for spoken languages). For example, in Spanish and LSU, Mesa de luz (Light table) is constituted by the lemma mesa (table) and the lexeme luz (light). Finally, factors such as familiarity, phonological neighborhood, and frequency of lexical pieces are equally relevant factors with important similarities in the processing of spoken and sign languages (Carreiras et al., Reference Carreiras, Gutiérrez-Sigut, Baquero and Corina2008).

Earliness and lateness in language exposition, iconicity in early vocabulary, and early lexical development in Deaf children

Within psycholinguistic aspects, the current literature on lexical organization and development of the Deaf has three main lines of discussion relevant for a comparative perspective as this of our manuscript: the debate about (a) the role of early experience in signing for early stages of lexical development, (b) the weight of iconicity on early vocabulary, and (c) the sign advantage in early lexical development for Deaf over hearing speakers.

1. (i) Language deprivation relates to the first line of discussion because this kind of privation is understood as the lack of linguistic stimuli that are necessary for the language acquisition processes. Early exposure to a first language—in our case, a sign language, LSU, and a spoken language, Spanish—is considered a predictor of future language and cognitive outcomes. For example, Mayberry et al. (Reference Mayberry, Chen, Witcher and Klein2011) found an “age-of-acquisition effect”: more activation in the posterior visual brain regions of deaf adults exposed late to ASL and less in the anterior linguistic brain regions while viewing sentences in ASL. The opposite was true for deaf adults exposed earlier to ASL. The authors interpreted late exposure to mean that linguistic information was more likely to be processed as visual information, a much less efficient means of language processing. Additionally, Caselli et al. (Reference Caselli, Hall and Henner2020) found that language deprivation has adverse effects on phonological processing, sign recognition speed, and accuracy. In a more general scope, these authors found that the form organizes the lexicons of both spoken and sign languages, that the recognition of lexicon occurs through form-based competition, and that form-meaning mappings do not drive lexical access even when iconicity is pervasive in the lexicon.

2. (ii) Regarding early vocabulary, Meier et al. (Reference Meier, Mauk, Cheek and Moreland2008) reported that iconicity is not a major factor in children’s phonological performance of their first signs. However, studies with the adapted MacArthur-Bates Communicative Development Inventories for some sign languages (American [Caselli et al., Reference Caselli, Pyers and Lieberman2021], British [Woll et al., Reference Woll, Meurant, Sinte, Herrmann, Steinbach and Zeshan2013], and Turkish [Sumer et al., Reference Sumer, Grabitz, Küntay, Gunzelmann, Howes, Tenbrink and Davelaar2017]) show conflicting evidence. Also, Lutzenberger (Reference Lutzenberger2018) shows how iconicity plays a role in the phonological development of sign language-acquiring children. Additionally, semantic categories seem a relevant factor in organizing the early vocabulary of sign-exposed children (Chen Pichler, Reference Chen Pichler, Pfau, Steinbach and Bencie2012, p. 659).

3. (iii) Finally, the sign advantage in early lexical development grounds the assumption that the parameters of the signs develop earlier than those of spoken languages. Consequently, Deaf children can produce lexical pieces earlier than hearers and accelerate the earlier stages of language development. Some studies support these claims (Bonvillian et al., Reference Bonvillian, Orlansky, Folven, Volterra and Erting1990; Morgan & Meier, Reference Morgan and Meier2008), and others do not (Meier & Newport, Reference Meier and Newport1990).

The environment

In asymmetric cross-modal language contact contexts, the main spoken language affects the development of a minority sign language and its spaces of use may be extremely limited (i.e., in the Deaf association, in the family if the parents or siblings sign). In these contexts, sign languages are viewed as misappropriated in some situations with the devaluation of sign languages. The minority sign language speaker would be forced to be fluent in the written form of the majority oral language, with the loss of features of the minority sign language (Adam, Reference Adam, Pfau, Steinbach and Bencie2012, p. 842).

This situation might inhibit the coining of new signs for the subjects of those contexts and the interest of the Deaf community to generate a more standard use of some signs. The effects of language contact include a range of phenomena such as borrowings and loans, interference, convergence, foreign talk, code-switching, language shift, language attrition, language decline, and language death (Thomason, Reference Thomason2001).

Furthermore, cross-modal language borrowing might have an impact on the lexicon of another language. McKee et al. (Reference McKee and Wallingford2011) described the importation of spoken lexical pieces into sign languages. This importation occurs through fingerspelling, mouthing, initialized sign formations, and loan translation. Foreign forms are another alternative. They combine structural elements of two languages, sometimes by mouthing and initialized signs. Adam (Reference Adam, Pfau, Steinbach and Bencie2012, p. 847) indicates that bilingual individuals (i.e., LSU-Spanish or vice versa) are instrumental in introducing new usages and coinages from a second language to the community. Nevertheless, Plaza-Poust & Weinmeister (Reference Plaza-Pust and Weinmeister2008, in Plaza-Poust, Reference Plaza Pust, Pfau, Steinbach and Bencie2012) showed that lexical and structural borrowing between German and German Sign Language (DGS) occurs at specific developmental stages for both languages and decreases as speakers progress and become fluent. Genesse, (2002, in Plaza-Pust, Reference Plaza Pust, Pfau, Steinbach and Bencie2012) demonstrated that individual variations in sign languages showed patterns similar to those found in comparative studies between spoken languages.

Cross-modal bilingualism is a set of situations in which more than one cross-modal second language is used by all or a large set of members of a community (bilingualism) or only a select group of members of this community is bilingual (bilinguality) in a cross-modal fashion. As indicated by Adam (Reference Adam, Pfau, Steinbach and Bencie2012, p. 847), lexical borrowing “… occurs when speakers in contact with another more dominant language (i.e., a spoken language such as Spanish) perceive a gap or a need of reference to new foreign concepts in their first language (i.e., LSU)…” As a result, the lexicon of the non-dominant language expands or new lexical pieces substitute existing pieces.

The present study

Space and time are universal experience domains for human beings. They are candidates for being salient in any language and culture. The Cognitive Linguistics approach (i.e., Lakoff & Johnson, Reference Lakoff and Johnson1980) considers space as a concrete domain of experience in that the human organism is posited to have perceptual-motor access to domain-specific information (i.e., sight and touch give us sensoriomotor spatial information about how tall or short a person is). In contrast, time is regarded as an abstract domain insofar as the absence of such sensorimotor access to domain-specific information (i.e., the orange color of the skyline and the low position of the sun are by themselves spatial information perceived by sensorimotor channels, but they are used for indicating or meaning a time interval of the day). Providing these spatial insights with a temporal meaning is not part of the visual information perceptual capture.Footnote ² As we indicated in the Introduction, there are some criteria for describing what is abstract or concrete. Then, in this study the concreteness/abstractness of space and time are domains considered as contrastive according to the criteria of access to sensoriomotor information, as it is done in the Cognitive Linguistics (Evans, Reference Evans2012) and Embodied Cognition (Wilson, Reference Wilson2002) frameworks.

This description of the concrete and the abstract has been evidenced in populations of different cultures and with verbal, non-verbal, and gesturing means. For a review, see Núñez and Cooperrider (Reference Núñez and Cooperrider2013), Bender and Beller (Reference Bender and Beller2014), and Callizo-Romero et al. (Reference Callizo-Romero, Tutnjević, Pandza, Ouellet, Kranjec, Ilić, Gu, Göksun, Chahboun, Casasanto and Santiago2020). However, the representation of space and time in spoken and sign languages presents similarities and differences whose effect on conceptualization and mental lexicon is still an open issue.

Unlike spoken languages, in sign languages, space is the substance in which linguistic production takes place. Wilcox and Martínez (Reference Wilcox and Martínez2020) suggest that the conceptualization of space in sign languages is manifested semantically and phonologically. This conceptualization gives semantic and phonological value to the space around the signer (sign space) and other locations (i.e., that of the objects to which the signer points, the location of those objects, and the movement of those objects in space) in a complex symbolic structure. This difference with spoken languages may suggest differences in linguistic modality important for the conceptualization of space and spatial memory (for the relation between spatial language and spatial memory in the Deaf population, see Karadöller et al., Reference Karadöller, Sümer, Ünal and Özyürek2022).

This research asks whether Deaf and hearing people have the same conceptual organization and construal profile (concrete vs. abstract) of the domains of time and space. Furthermore, we delve into what semantic networks can tell us about the memory processes involved in the conceptual categorization of both Deaf and hearing populations. Semantic networks show how memory describes the organization of declarative facts and knowledge in the mind (see Collins & Loftus, Reference Collins and Loftus1975). The value of this research lies in the evidence it provides about the similarities and differences of the “construal profile” of space and time mental lexicon between linguistic modalities, considering that the language modality could explain the variability of these construals. The study aimed to describe the components of the time and space domains in the Deaf-signing population of LSU and the Spanish-hearing population of Uruguay through a free word association task. It also sought to contrast the domains of interest between these two populations to explore the effects of linguistic modality on the conceptualization of the domains of time and space.

This study hypothesized that if the linguistic modality differences have effects on conceptual categorization, then there might be biases between types of categorization or construals by modality consistent with alternatives in the use of sensorimotor, linguistic, and social information. Because iconicity relies on concreteness (in which sensorimotor information becomes more relevant) and iconicity is pervasive in sign languages, Deaf signers may prefer semantic relations more sensitive to sensorimotor information and concrete construals than hearing speakers. Preferences could take the form of a bias toward concrete construals of the domains of space and time for the signer population (mostly syntagmatic responses and semantic relations of entity and situation), but not for the hearing population.

In our search for an instrument that is balanced in terms of evoking perceptual-motor, social, and linguistic information, free word association tasks seem an appropriate paradigm for a first approach (De Deyne et al., Reference De Deyne, Navarro, Collell and Perfors2021). This paradigm allows for the capture of all types of responses (syntagmatic vs. paradigmatic), all types of semantic relations (taxonomy vs. entities vs. situation vs. introspection), and all types of lexical pieces (open vs. closed). To answer our research questions, we performed what we call a repeated free word association task with dual-class (open such as nouns or verbs and closed such as conjunctions and prepositions) pieces in a concurrent domain clue format. That is, dichotomous lexical pieces as members of the same domain (e.g., ABAJO [Down] and ARRIBA [Up] for the spatial domain and PASADO [Past] and FUTURO [Future] for the temporal domain) were presented in the target concepts, in addition to filler clues. In this way, we believe it is possible to prime an intra-domain response from participants in both populations (i.e., Deaf and hearing) and to have more powerful data for between-group comparisons.

Regarding how time is expressed in sign languages, Pereiro and Soneira (Reference Pereiro and Soneira2004, pp. 65–66) suggest that time is coded by using lexical items, grammatical elements, or timelines. The authors mention three predominant timeline expressions in sign languages around the world: one perpendicular to the signer’s body, the other located in front of the signer’s body, and the last labeled as the growth line. Sign languages studied so far (Emmorey, Reference Emmorey2001) present together a wide repertoire of timeline alternatives. Bringing together the various timelines mentioned in different Sign Languages (i.e., American, Australian, British, Danish, French-Belgian, Spanish, and other three cases), Sinte (Reference Sinte, Herrmann, Steinbach and Zeshan2013) proposed a set of six unidimensional timelines and a grid labeled as a plane.

In contrast, in spoken languages, only some spatial lexical items are used with temporal value. For example, back, forward, up, and down words do (i.e., Spanish expressions such as El pasado quedó atrás “The past is behind us” makes sense but El futuro quedó a la derecha “The future left to right” does not). Instead, left and right words have no temporal value in any spoken language (Haspelmath, Reference Haspelmath1997).

This research asks whether Deaf and hearing people have the same conceptual organization and construal profile (concrete vs. abstract) of the domains of time and space. Furthermore, we delve into what semantic networks can tell us about the memory processes involved in the conceptual categorization of both Deaf and hearing populations. Semantic networks show how memory describes the organization of declarative facts and knowledge in the mind (see Collins & Loftus, Reference Collins and Loftus1975).

General discussion

This study examined the similarities and differences of the conceptual organization of the domains of time and space in Deaf and hearing populations in Uruguayan society through a property list task. The relevance of this study lies in that similarities and differences found between linguistic modalities that could affect and differentiate the mental lexicon and the structure of categorization of concepts in these populations: more concrete (entity and situational) or abstract (taxonomic and introspective) organizations of these domains between the examined populations.

To explore universal possible domains of human experience, we select concepts distinguishable in their processing, that is, concepts involve sensorimotor, linguistic, and social information in different modes. Fundamentally, were chosen concepts that include the dimensions of space and time. The former is labeled concrete in cognitive literature and the latter as abstract.

The hypothesis of this study was that if the linguistic modality differences have effects on conceptual categorization, then there might be construal biases between modalities consistent with alternatives in the use of sensorimotor, linguistic, and social information. Thus, we might find differences in the types of semantic relations they showed as preferred by each population and, consequently, differences in the abstract or concrete way of conceptualizing or evoking (construal) the conceptual domains of time and space. In line with these differences, the expectation was that there would be a bias of the Deaf population toward a concrete construal because of the higher iconicity of sign languages and the link of the former to concreteness and sensorimotor information. In principle, we did not expect this bias in the hearing population. The different types of iconicity (i.e., pantomimic, perceptual, or diagrammatic), its scope (total or partial), and its complementarity with metaphoric or metonymic processes can vary the scope of the different signs to evoke situational semantic relations on other alternatives, priming a crucial element of a concrete thought. A design with a more counterbalanced set of clues might help to better measure the effect of iconicity on the observed categorization biases.

To do this, the semantic networks were reconstructed from the relationships between the properties stated for each concept. Then, we use the semantic networks to describe the memory processes and organization involved in conceptual categorization among Deaf and hearing populations.

To test these similarities and differences, a repeated free association task was chosen because this paradigm captures all types of responses (syntagmatic vs. paradigmatic), all types of semantic relations (taxonomic vs. thematics), and all types of lexical pieces (open vs. closed).

The language modality differences can be grouped into four major sets: semiotic, linguistic, psycho, and sociolinguistic. This study assumed the morphological and phonological character of space in sign languages and the absence of such a value for spoken ones. Note that the greater pervasiveness of iconicity in sign languages seems to be genuine modality difference.

We warned that concrete and abstract thinking is not exclusive to any examined populations and we dealed only with some ways of describing them. The study distinguished concreteness and abstractness on two levels: first, in function concerning the availability of sensorimotor access to domains of experience, and second, concerning how semantic relations between clue and associate show a way of organizing those domains in semantic memory.

The study showed that the latter approach captures the eventual biases of a linguistic modality when the speaker population of that modality defines the most relevant attributes to identify a lexical item and its relevant semantic environment. In this sense, the study suggests that the difference between taxonomic and thematic semantic relations between the clue and its associates could be interpreted as evidence of a bias for an abstract versus a concrete construal of the domains. The expected differences in the construal of the domains of space and time between the populations are because the morphological and phonological value of space, the pervasiveness of iconicity in sign language, and the strong link between iconicity and concreteness would facilitate a concrete construal in the Deaf population.

The results suggest that the mental lexicon between the two populations (Deaf and hearing) differs significantly in several respects organization and semantic categorization. About the similitudes, entropy did neither show significant intra-group differences, nor kind of clues differences (space and time vs. fillers). Because each intra-group diversity is similar for the two compared groups (i.e., Deaf and hearing), then we suggest that there are structural similarities (i.e., clustering, betweenness, density) in the semantic networks and the organization of the tested mental lexicon between the two populations for the study. These findings are consistent with the literature that compares mental lexicon (Dubossarsky et al., Reference Dubossarsky, De Deyne and Hills2017). This literature suggests that lexical processing and lexical semantics might show important similarities with respect to mental lexical organization, retrieval, and recall. In the design of the task, antonym clues (i.e., Back vs. Front) were systematically provided for space and time clues than for filler clues. Then, this difference might facilitate more syntagmatic associates and thematic thinking for the filler clues than the space and time clues.

In the scope we know, the previous comparative norming studies between Deaf and hearing populations are scarce (Marschark et al., Reference Marschark, Convertino, McEvoy and Masteller2004). Then, comparing similar previous studies with similar pairs of populations (Deaf vs. hearing nonsigners) to understand better and weigh our results’ scope takes work. Coinciding with Marschark et al. (Reference Marschark, Convertino, McEvoy and Masteller2004), our results showed more robust taxonomic thinking (i.e., associations between category names and exemplars) in the hearing population than in the Deaf one.

If most of the Uruguayan Deaf population—there are no statistical records but the Uruguayan specialist agrees on this topic—is below or reach an early learning phase of Uruguayan Spanish (level A in CEFR), our findings seem in line with those of Dong and Li (Reference Dong and Li2015) with bilinguals of two spoken languages: in an early learning phase of a spoken language such as Spanish, it might be expected that the conceptual integration between translation equivalents of L1 (in our case LSU) and L2 (Uruguayan Spanish) is far from being.

Another antecedent of these kinds of studies was done by Karadöller et al. (Reference Karadöller, Sümer, Ünal and Özyürek2022), but in these studies, only Deaf (Turkish Sign Language) made elicited picture descriptions and the experimenters tested the subsequent recognition memory accuracy of the described pictures. Mainly, this study did not get a spatial memory but rather linguistic conceptualization of space and time.

Given the paucity of semantic norm studies to compare Deaf and hearing populations, we believe it is more appropriate to compare our results with those of populations of strongly different languages, age groups, professions, or other differentiating criteria even among hearing populations. We warn that since this study does not focus on those variables (i.e., age, profession, etc.), we do not have words on how it affects categorization of time or space. According to this criterion, like older adults and children, the Deaf group showed a greater tendency to establish thematic relations. Like young adults (García Coni et al., Reference García Coni, Comesaña, Piccolo and Vivas2020), the hearing group showed a greater tendency to taxonomic relations.

This similarity of results suggests that psycho- and sociolinguistic factors—non-controlled in this study or directly included as variables—such as language deprivation, asymmetric language contact, and bilingualism between a sign and a spoken language might influence the shape of semantic networks, as well as the semantic relations preferred by speakers. Because these aspects were non-controlled in the sample, we only briefly acknowledge that they might be relevant in further studies.

Notably, the semantic categories (taxonomy, entity, situation, and introspection) chosen by each population (Deaf vs. hearing) show different preferences between them: a bias toward an abstract construal in the hearing population and a bias toward a concrete alternative in the Deaf population. We notice that in our study, the classification of concrete and abstract refers to the pairs clue-associate (i.e., taxonomic and introspective as abstract relations and entity and situation as concrete ones). However, introspective relations might capture proprioceptive information not included in Borghi’s et al. (Reference Borghi, Binkofski, Castelfranchi, Cimatti, Scorolli and Tummolini2017) proposal. It is in line with sensorimotor one and might support concrete construal of any domain. We warn that abstractness is present in some other non-tested ways. For example, some kinds of iconicity, which are present in sign languages, such as structure mappings, are quite an abstract process.

Although we did not wonder whether Deaf signers or hearing nonsigners choose verbs, nouns, or adjective forms for providing the associates, we believe it is an interesting question because it provides—in line with the distinction between processes and entities suggested by Langacker (Reference Langacker1987)—a way for capturing differences in the conceptualization strategies of the populations of the study. We already said that distinguishing word classes in the participants’ responses was helpful to the study’s aims. When translating the associates provided by Deaf participants, we controlled the word classes of all their responses as most as possible. Then our data might be helpful for answering questions about the word classes preferred by the participants and doing intra- and between-group comparisons.

Another different criterion is the gap between oral and literate cultures. From this classification, sign language and speech corresponds to oral culture and written form of spoken languages to a literate one. Ong and John (Reference Ong and John1982) argues that in an oral culture thought and expression do not handle categorizations by abstraction or formally logical reasoning processes. We warn that not all spoken languages have a written form, and many times Deaf signers are literate in a spoken language. It means that literate Deaf and hearing writers have access to what Ong and John (Reference Ong and John1982) calls oral and literal culture and the kind of categorization and reasoning they support. Usually, taxonomic relations such as those between clue-associate pairs are based on abstract logical reasoning. These assessments are suggestive of our findings, but the design of the free word association task needs to be changed for testing a specific hypothesis for this approach.

This study can be framed within the claims of linguistic determinism (see Gumperz et al., Reference Gumperz, Levinson and Levinson1996; Hickmann, Reference Hickmann2000). For this approach, language constrains human knowledge and thought processes such as categorization, memory, and perception. Then, individuals’ thinking partially differs across linguistic communities. Would language modality be a constraining factor different from the differences between languages of the same modality? Our theoretical framing and claiming suggest iconicity as a powerful contrasting factor. This study is limited in some ways in drawing large conclusions about this. However, the results are biased in favor of partial differences in the structure of the mental lexicon and semantic relationships highlighted by each language modality. The question of whether all languages make the same ontological commitment to notions such as “entity” as opposed to notions such as “situation” (those used in our coding tool and those that inspired it) suggests that such distinctions might impact everyday language behavior and controlled experimental tasks.

Limitations and future avenues

Free associations of words are quite unpredictable. Then, the semantic networks we report here would have variations by criteria such as others we tested, including other clues, a larger group of participants, or even these same participants at another time. In consequence, our claims about the differences between the studied populations have limitations according to these warnings. These warnings aim to explore future avenues that we suggest at the last paragraph. Regarding the study’s limitations, three of the eleven dyad-shaped clusters were formed by pairs of antonymous concepts. This result may be a product of the design of concurrent pairs per domain, mainly for space and time clues. This result is consistent with the findings of Zapico and Vivas (Reference Zapico and Vivas2014), who found antonymous word pairs in a study of synonymy as a type of semantic distance. In line with previous explanations, the small sample size of our study is a crucial limitation for getting stronger conclusions. One might expect that the larger the sample, the more the semantic networks of the two groups converge (i.e., QAP and entropy test might indicate this convergence).

The categories used in the coding tool and the composition of the judging team should be critically considered. The semantic categories in that tool follow a speech-centered perspective and there were no Deaf members on the judging team. Regarding the former, creating a tool with categories fully valid for both linguistic modalities (sign and spoken) is necessary to measure the possible biases associated with the current categories accurately. Still, it remains in doubt whether, by definition, the categories (entity vs. situation vs. introspection vs. taxonomy) represent in an exclusive way speech-center thinking. Perhaps, the adaptation should focus on the subcategories and other aspects such as the analysis unit (i.e., perhaps phrases that behave partially as lexical items in a sign but not in a spoken language).

Regarding the second, applying such a tool would be the appropriate way to form teams of judges that include Deaf and hearing people in a balanced way. In turn, this would help better estimate the possible effect of the grammatical class of the clues and associated in the application of the tool on semantic relations.

A last limitation is the ability of socio-demographic variables, such as age and education, to capture differences in cognitive and linguistic development between some kind of populations. We believe that these variables can be blind tools to explore in a refined way and with a common metric the equivalence in cognitive and linguistic development between populations. As a surrogate for these measures, standardized instruments adapted to Deaf and hearing populations (i.e., MacArthur Communicative Development Inventory [Anderson & Reilly, Reference Anderson and Reilly2002] or Non-verbal intelligence tests for Deaf and hearing subjects [Snijders & Snijders-Oomen, Reference Snijders and Snijders-Oomen1959]) would be more accurate alternatives for matching the Deaf and hearing nonsigner samples in verbal fluency and abstract and spatial thinking.

Future avenues of research include expanding the sample; comparing the Deaf sample with subsamples of the Rioplatense Spanish lexicon (Vivas J. et al., Reference Vivas, Vivas, Comesaña, García Coni and Vorano2017; Cabana et al., Reference Cabana, Zugarramurdi and De Deyne2020) and other spoken-sign languages pairs such as DGS-German, CSL-Mandarin, LSE-Spanish, or ASL-English; testing bimodal bilinguals would help to find whether they follow the pattern of Deaf signers, hearing nonsigners, both, or neither. Mainly, the cross-linguistic approach might help to clarify whether the patterns that we found here are due to modality effects or artifacts of the tested specific languages (LSU and Uruguayan Spanish). Other alternatives to follow are comparing the weight of phonological similarity (word family) in clue-associative pairs, due to the greater weight of word families in the lexical structure of sign languages; comparing the proportion in the selection of open- and closed-class pieces in clue-associative pairs, due to the greater weight of word families in the lexical structure and the greater discourse profile of sign languages; and conducting similar studies in other sign languages and their spoken counterparts.