3.1 Anti-uniqueness presupposition of ‘every’

Using a felicity judgment task, Yatsushiro (2008a; b) experimentally investigated German children’s acquisition of the anti-uniqueness presupposition of jeder ‘every’. Yatsushiro grounds her hypotheses in the developmental literature on scalar implicatures which suggests that younger children produce much less pragmatic interpretations, with a clear developmental curve (Noveck 2001; Chierchia et al. 2001; Gualmini et al. 2001; Papafragou & Musolino 2003; Guasti et al. 2005; Pouscoulous et al. 2007; Huang & Snedeker 2009; Tieu et al. 2014; Singh et al. 2016; among others). Participants (four age groups from 6 to 9 years) were presented with three target conditions: a scalar implicatures using einige (some); a test of the lexical presupposition (existence) of jeder; a test of the implicated presupposition (anti-uniqueness) of jeder. The items used a visual context for two sentences presented by two dolls. The participants had to reward the doll that said better what happens in the picture. As an example, in the implicated presupposition condition, a picture of a single girl playing football was shown, while the sentences were as follows:

Yatsushiro found a difference between the 6-year-old and the 7-year-old groups, with the younger children giving less pragmatic answers in the scalar and implicated presupposition conditions. She interpreted this as support for the hypothesis that the acquisition of both types of inferences have similar developmental trajectories. Based on that, Yatsushiro proposed that a) lexical presuppositions are acquired earlier than implicated presuppositions, and b) implicated presuppositions follow the developmental path of scalar implicatures.

3.2 Acquisition of the pair <know, think>

Dudley et al. (2015) present a comprehensive systematization of the kinds of developmental studies which investigate the acquisition of know and places them in three groups: i) negation tasks which distinguish the non-factive think from the factive know because only the latter but not the former allow the factive presupposition to project through negation (cf. Harris 1975; Hopmann & Maratsos 1978; Scoville & Gordon 1980; Léger 2007; among others); ii) metalinguistic tasks in which participants are asked to decide whether a character knows a proposition or believes it (Macnamara et al. 1976; Abbeduto & Rosenberg 1985; among others) and iii) relative strength tasks (cf. Moore & Davidge 1989; Moore et al. 1989; Falmagne et al. 1994; among others). Many of these studies suggest that younger children do not have an adult-like representation of know. In contrast, Dudley et al. (2015) argue that even children as young as 3 years of age can have an understanding of the presuppositional property of know. While none of the above-mentioned studies directly addressed acquisition of implicated presuppositions, some of the previous results can be re-interpreted in the light of MP. This is the case for Moore & Davidge’s (1989) study, where children (aged 3–6 and divided into four age groups) were asked to find a candy hidden in one of two differently colored boxes, following the hints given by two bears. One of the bears would use think (‘I think it’s in the red box’), and the other would use know (‘I know it’s in the blue box’). In order to choose the bear that ‘knows’ rather than the bear that ‘thinks’, children would not only have to have mastered factivity relative to know, they would also have to compute the inference of anti-factivity (the implicated presupposition) with respect to think, as expected on the basis of the literature on implicated presuppositions reviewed above (e.g. Sauerland 2008). The results showed that 3-year-olds scored significantly lower than all other age groups, suggesting that the implicated presupposition is not drawn before 4 years of age. These results were confirmed by a later study (Moore et al. 1989).

3.3 MP: a possible developmental path

Stateva & Stepanov (2021) investigate whether the acquisition of MP-related inferences is subject to a developmental trajectory. It is argued that successful passing a Theory of Mind (ToM) test (cf. Wimmer & Perner 1983, Baron-Cohen et al. 1985; Wellman et al. 2001; Liu et al. 2008; among others) and acquisition of know as a factive verb (or, rather, its lexical presupposition of factivity; cf. Moore & Davidge 1989 but also Schulz 2003) are two prerequisites for an adult-like knowledge of applying MP to the <know, think> pair. The authors conducted an experiment that included two parallel tasks. One task probed children’s knowledge of Theory of Mind, and the other, a felicity judgment task, knowledge of lexical presupposition of factivity, as well as sensitivity to MP, in two groups of Slovenian pre-school and early school children, specifically, 5- and 7-year olds. The choice of this age group was determined by the finding that the bulk of the acquisition of scalar implicatures, a parallel type of pragmatic inferences, takes place in children between 4 and 8 years of age, with some exceptions (Feeney et al., 2004; Guasti et al., 2005; Katsos & Bishop 2011; Foppolo et al. 2012; Skordos & Papafragou 2014; among others). Only the results of the children who successfully passed the ToM task were analyzed in the felicity judgment task. Children in this experiment performed similarly on the condition testing lexical presupposition of factivity and condition testing the knowledge of MP within each age group, with success rates in felicitous responses increasing accordingly with age (age did not interact with condition). While 7-year old children in this study performed practically at ceiling on lexical presupposition and slightly less so on the MP condition, performance of the 5-year olds on both conditions was only 70–76% successful. The less than ceiling result in the 5-year-old group suggests that the lexical presupposition property of the Slovenian verb vedeti (‘know’) was not fully acquired within this age group. The generally high accuracy (>90%) of performance on the MP-related condition in 7-year-olds suggested that at this age, children have adult-like knowledge about MP. These results reinforced the earlier conclusion that knowledge of MP is contingent on the lexically-grounded knowledge of the presuppositional contrast between the know and think-type predicates, which is expected to come along with acquisition of the predicates themselves and be in place at that age.

3.4 The role of bilingualism in deriving MP-related inferences

An issue that we believe deserves separate attention in light of children’s computation of pragmatic inferences attributed to MP concerns the potential role of bilingualism in this process. In order to appreciate this special role, let us clearly articulate what ‘knowledge of MP’ implies for our purposes. We assume that it encompasses the following competences and abilities:

1. knowledge about asserted meaning,

2. knowledge about presupposed meaning,

3. general ability to recognize a competition between relevant (linguistic and non-linguistic) alternatives and ability to access these alternatives,

4. ability to resolve the competition.

While the first two competences can be directly linked to linguistic knowledge, the abilities to recognize and to resolve a competition, as in iii) and iv), are relevant in general cognitive domains. Competition resolution, understood as inhibition of competing information, is widely argued to be part of executive control processes (Baddeley 1986, Posner & Petersen 1990, Miyake et al. 2000). With respect to bilingualism, studies in lexical access reveal that interlocutions activate translational equivalents in the bilingual mind and those in the non-target language are inhibited, thus suggesting that inhibition, being an executive function, is positively influenced by bilingualism (Green 1998; Costa et al. 1999; Abutalebi & Green 2007; Costa et al. 2008; Ivanova & Costa 2008; Guo et al. 2011; Misra et al 2012). That bilingualism contributes to an enhanced inhibition function of the Executive Control system was also a conclusion of a number of experimental studies on perceptual conflict tasks, e.g. Stroop or Simon tasks, which require inhibition of irrelevant information. Other results confirm a bilingual cognitive advantage in the domain of Executive Control abilities (e.g. Bialystok 1999; 2010; 2011; Bialystok et al. 2009; Antoniou et al. 2016), although the effect tends to be selective, depending on many factors such as type of bilingualism, type of task etc., rather than being across-the-board (see Adesope et al. 2010; Valian 2015; Calvo et al. 2016 for detailed reviews). Importantly, most experimental work suggests that such cognitive advantages are associated with children, including pre-verbal ones (cf. Kovács & Mehler 2009a; b; Brito & Barr 2012), as well as older populations experiencing deficits in the cognitive reserve (a resource resulting from intelligence, education, life-time acquired knowledge; cf. Stern 2009) generally related to varieties of brain damage, but not often with speakers in their cognitive primes, i.e. (young) adults (cf. Bialystok et al. 2005; 2008; Salvatierra & Rosselli 2011). The relevance of these studies to our interest in MP follows from the assumption that adherence to MP depends on competition resolution and consequently an enhanced inhibitory function, most pronounced in children. To the extent these findings pertain to choosing among competing alternatives, they substantiate an inquiry about the role of bilingualism in processing inferences due to MP assuming competition resolution as a relevant mechanism, in particular, exploring a reasonable hypothesis that enhanced abilities related to inhibition (and possibly executive functioning) could give bilingual children an advantage in adherence to MP.⁴

Although, to our knowledge, no previous research directly addressed the influence of bilingualism on processing MP-related inferences, a limited number of studies compared the development of pragmatic abilities of early bilingual and monolingual children, in particular, in the domain of scalar implicatures. The state of the art provides two divergent claims, although the second one is heavily prevailing:

1. Early bilinguals slightly outperform monolingually developing children in the production of implicatures. The advantage could be attributed to non-linguistic abilities linked to bilingualism (Siegal et al. 2007; 2009; 2010).

2. There is no robust evidence that suggests a multilingual advantage in the comprehension of scalar implicatures (Antoniou et al. 2013; Syrett et al 2017; Antoniou & Katsos 2017; Dupuy, Stateva et al. 2019).

The results of Antoniou et al.’s (2013) study can be subjected to scrutiny given that they compare multilingually growing children to children speaking two dialects of Greek and in that sense the study does not really evaluate bilingualism as a factor in comprehending scalar implicatures. No such obvious objections can be raised against the findings of Dupuy, Stateva et al. (2019) and Antoniou & Katsos (2017). These works show a numerical advantage of the bilingual participants in the comprehension of scalar implicatures, which, however, does not reach significance. Finally, some studies attempted to establish a correlation between enhanced performance on executive abilities tasks and a higher rate of implicature comprehension but the results again do not reach significance (cf. Siegal et al. 2007; 2009; 2010). To sum up, bilingualism may be reasonably placed as a major factor potentially affecting children’s computation of MP-related inferences. This, together with the general question as to how these inferences are computed in real time (see above), opens an interesting venue for further exploration.

4.1 Participants

We recruited sixty-three monolingual Slovenian, fifty-nine monolingual Italian and sixty-four bilingual Slovenian-Italian child participants (total N = 186), assigned to three age groups, namely nine-, eleven- and thirteen-year-olds. Our decision about the age of the target group of this study was based on several guiding criteria: i) a reliable lexical knowledge of the <know, think> pair, especially the presuppositional properties of know, in both languages in the case of bilingual participants; ii) a sufficient vocabulary to understand complex sentences with embedded complements, as well as sufficient writing abilities to pass the language proficiency test, in the case of bilinguals (see Section 4.2.1), and iii) maximizing the probability of an adult-like acquisition of scalar implicatures. Regarding i) and ii), a number of studies of language proficiency of bilingually growing children show that they lag behind their monolingual peers in lexical acquisition (cf. Bialystok et al. 2010) as well as complex grammatical variables (Oller & Eilers 2002; Nicoladis et al. 2007; Paradis 2010). Bialystok et al. (2010) reports data from the administration of the Peabody Picture Vocabulary Test (Dunn & Dunn 1997) to 1738 children between 3 and 10 years of age divided into 8 age groups. In each of these groups the bilinguals demonstrated a significantly lower score of receptive vocabulary in English. Similar results from studies on a smaller scale have been reported in Siegal et al. (2007) and Antoniou & Katsos (2017), among others. Regarding iii), some developmental studies on the comprehension of scalar implicatures show that even 9-year-old children still produce less pragmatically strengthened interpretations than adults (cf. Noveck 2001). The interval between 9 and 13 years of age thus offers a promising opportunity to reliably track children’s performance in MP-related tasks in the context of bilingual language development.

Children were selected on the basis of an extensive questionnaire filled out by their parents in addition to a signed parent consent form (the questionnaire had a different form for monolingual and bilingual participants concerning their language background). Monolingual participants were recruited from five elementary schools in the region of Nova Gorica, Slovenia, two elementary schools in the region of Gorizia and Udine and two summer camps in Gorizia and Udine, Italy, respectively. Bilingual children were recruited from four elementary schools serving the bilingual communities in the Gorizia region (Italy), the cities of Izola, Piran, and Koper and the Music school in Nova Gorica (Slovenia). We targeted early bilinguals who were introduced to either Slovenian or Italian at birth and AoA (age of acquisition) of the second language of the pair was not greater than 3. The monolingual and bilingual groups of children were matched by age and socio-economic status. We also checked that each group of monolingual children contained only children who were not exposed to any other language outside of the standard school curriculum.

In addition, 20 adult native speakers of Italian and 22 adult native speakers of Slovenian (total N = 42) participated in the experiment serving as controls.

4.2 Design and materials

4.2.2 The main experiment

The main experimental design assesses children’s sensitivity to lexical presupposition of factivity (LP) by testing their knowledge of the factivity of vedeti or pensare (‘know’), and at the same time their sensitivity to MP, in a within-subjects design. The type of visual and story-telling material we created for this task was similar in spirit to material usually used in ToM tasks (cf. MP: a possible developmental path) because it manipulates false and true beliefs of the attitude holder, with one important modification: ours was a felicity judgment task in the target conditions of which participants are expected to choose between two truth-conditionally equivalent assertions, one of which is more felicitous than the other which related to the background story. Every item in our experimental material includes a sequence of 4 images, each of which accompanied by a sentence, that together tell a short story involving two main characters. There were three conditions in the stimuli and 8 story items per condition. Condition LP (‘lexical presupposition’) examines children’s representation of know as a factive verb and tests for a respective lexical presupposition. It describes an event in which Character 2 moves the relevant object to a new location but the test sentence makes reference to the initial location in which Character 1 has put the object. A sample item from the Condition LP is given in Figure 1.

Figure 1

Sample story for Condition LP (actual stimuli are in Slovenian or Italian).

In this condition, the pair contains an example like (7) whose presupposition is not satisfied in the context and a minimally different sentence (8) which is both felicitous and true.

1. (7)

1. Babica
2. Granny
1. ve,
2. knows
1. da
2. that
1. je
2. is
1. torta
2. cake
1. na
2. on
1. mizi.
2. table
1. ‘Granny knows that the cake is on the table.’

1. (8)

1. Babica
2. Granny
1. misli,
2. thinks
1. da
2. that
1. je
2. is
1. torta
2. cake
1. na
2. on
1. mizi.
2. table
1. ‘Granny thinks that the cake is on the table.’

This pair is irrelevant to MP since the constraint requires that only alternatives that are both true and felicitous in a given context are compared. In the case (7) the complement is not true, therefore the alternative should not be chosen. Choosing alternative (8) indicates that children are sensitive to the lexical presupposition associated with know.

The second condition, Condition MP, was intended to probe into knowledge of MP. In the respective story, Character 2 does not move the relevant object from its initial position. Figure 2 illustrates a sample item for this condition.

Figure 2

Sample story for Condition MP (actual stimuli were are Slovenian or Italian).

A sample target pair of Condition MP sentences is illustrated in (9)–(10):

1. (9)

1. Ciril
2. Cyril
1. misli,
2. thinks
1. da
2. that
1. je
2. is
1. flavta
2. flute
1. na
2. on
1. postelji.
2. bed
1. ‘Cyril thinks that the flute is on the bed.’

1. (10)

1. Ciril
2. Cyril
1. ve,
2. knows
1. da
2. that
1. je
2. is
1. flavta
2. flute
1. na
2. on
1. postelji.
2. bed
1. ‘Cyril knows that the flute is on the bed.’

In view of MP, (9) and (10) are potential alternatives because they are truth-conditionally equivalent and differ by presupposed content. In contexts that satisfy the presupposition triggered by know in (10) the competition between (9) and (10) is resolved in the felicitous use of (10). In other words, MP predicts (10) to be preferred in this context since only that sentence presupposes the truth of its complement. The think-alternative in such contexts is true if Cyril holds a belief that the embedded proposition holds (viz. that that the flute is on the bed) but it is infelicitous given that the know-alternative is presuppositionally stronger. In contexts that do not support the presupposition of (10), the latter is infelicitous. On the other hand, under MP, the interpretation of (9) in such contexts is strengthened by adding an implicated presupposition that the presupposition of its alternative is not satisfied.⁶

Each story item was additionally supplanted with two closed type comprehension questions related to the content of the story. A sample pair, related to the story in Figure 2, is given in (11)–(12):

1. (11)

1. Kam
2. Where-to
1. je
2. is
1. Ciril
2. Cyril
1. položil
2. put
1. flavto?
2. flute
1. ‘Where did Cyril put the flute?’

1.  
1. a)

1. Na
2. on
1. posteljo
2. bed
1. ‘On the bed’

1.  
1. b)

1. Na
2. on
1. stol
2. armchair
1. ‘On the armchair’

1. (12)

1. Kje
2. Where
1. je
2. is
1. flavta
2. flute
1. zdaj?
2. now
1. ‘Where is the flute now?’

1.  
1. a)

1. Na
2. on
1. postelji
2. bed
1. ‘On the bed’

1.  
1. b)

1. Na
2. on
1. stolu
2. armchair
1. ‘On the armchair’

This comprehension task served a purpose to check participant’s attentiveness, and accuracy of responses to comprehension questions served as an exclusion criterion (see Section 5.3).

The Italian counterparts of the sample target sentences for Condition LP (cf. 7) and (8)) are given in (13) and (14), those for Condition MP (cf. (9)–(10)) are given in (15) and (16):⁷

1. (13)

1. La
2. the
1. nonna
2. granny
1. pensa
2. thinks
1. che
2. that
1. il
2. the
1. dolce
2. cake
1. sia
2. be
1. sul
2. on-the.
1. tavolo.
2. Table
1. ‘Granny thinks that the cake is on the table.’

1. (14)

1. La
2. the
1. nonna
2. granny
1. sa
2. knows
1. che
2. that
1. il
2. the
1. dolce
2. cake.
1. è
2. is
1. sul
2. on-the
1. tavolo.
2. table
1. ‘Granny thinks that the cake is on the table.’

1. (15)

1. Luca
2. Luca
1. pensa
2. thinks
1. che
2. that
1. il
2. the
1. flauto
2. flute
1. sia
2. be
1. sul
2. on-the
1. letto.
2. table
1. ‘Luca thinks that the flute is on the table’

1. (16)

1. Luca
2. Luca
1. sa
2. knows
1. che
2. that
1. il
2. the
1. flauto
2. flute.
1. è
2. is
1. sul
2. on-the
1. letto.
2. table
1. ‘Luca knows that the flute is on the table’

In addition, we were interested in estimating the role of negation in demonstrating sensitivity to MP in the context of the know-think pair. To that effect, we introduced another experimental condition, Condition MP-Neg. This condition probes into knowledge of MP in negated sentences such as (17)–(18). In contrast to Condition MP, in Condition MP-Neg, Character 2 moves the object to a new location and the target sentences, now involving one of the verbs from the know-think pair combined with negation, make reference to that location, as illustrated in Figure 3. The corresponding Slovenian target sentences are in (17)–(18), the Italian counterparts are in (19)–(20).

1. (17)

1. Bobi
2. Bobby
1. ne
2. not
1. ve,
2. knows
1. da
2. that
1. je
2. is
1. kost
2. bone
1. v
2. in
1. moji
2. my
1. roki
2. hand
1. ‘Bobby doesn’t know that the bone is in my hand.’

1. (18)

1. Bobi
2. Bobby
1. ne
2. not
1. misli,
2. thinks
1. da
2. that
1. je
2. is
1. kost
2. bone
1. v
2. in
1. moji
2. my
1. roki.
2. hand
1. ‘Bobby doesn’t think that the bone is in my hand.’

1. (19)

1. Bobi
2. Bobby
1. non
2. not
1. sa
2. knows
1. che
2. that
1. l’osso
2. the-bone
1. è
2. is
1. nella
2. in-the
1. mia
2. my
1. mano
2. hand
1. ‘Bobby doesn’t know that the bone is in my hand’

1. (20)

1. Bobi
2. Bobby
1. non
2. not
1. pensa
2. thinks
1. che
2. that
1. l’osso
2. the-bone
1. sia
2. be
1. nella
2. in-the my
1. mia
2. hand
1. mano
2.  
1. ‘Bobby doesn’t think that the bone is my hand.’

Figure 3

A sample item for Condition MP-Neg (actual stimuli are in Slovenian or Italian).

A priori, in the context depicted in Figure 3, both sentences are true but the ‘doesn’t know’ option presupposes more and is the targeted choice in view of MP.

In sum, there were 8 stories for each of the three conditions (24 stimuli total), and 3 questions following each story which included 2 comprehension questions and the target request (72 questions total). Monolingual and bilingual participants were tested on all target 24 stories. We tested the bilingual participants in both of their languages. Following the methodology in Dupuy, Stateva et al. (2019), bilingual speakers received half of the items in Slovenian and the other half in Italian.⁸ Within each language, the order of stimuli was pseudo-randomized for each participant by the (custom-created) presentation software. A full list of stimuli is available on request from the first author.

4.3 Experimental predictions

4.4 Procedure

5.1 Statistical analyses

For inferential statistical analyses of the main conditions in this study, we used mixed effects logistic regression models in R version 4.0.2, using the glmer function from the lme4 package (Baayen et al 2008; Jaeger 2008; Bates et al. 2014; R Core Team 2020). Felicitousness of the chosen alternative in answering the target question was coded as a binary-valued dependent variable reflecting felicitous and non-felicitous answers, respectively. Logit model estimates are given in log odds (logarithms of odds of giving a targeted answer), which can be converted to probabilities by taking an inverse logit [logit^–1(α) = exp(α)/(1 + exp(α)]. Effects are graphically illustrated by predicted probabilities on the logit scale. In estimating main effects and interactions, we report χ² and p-values based on the likelihood-ratio test, whereby a model containing the fixed effect of interest is compared to a model that is identical in all respects except the fixed effect in question. In each analysis, the best fitting model was chosen by comparing pairs of models with different degree of complexity using the likelihood ratio test. The simplest model considered included only by-subject and by-item random intercepts. More complex models included by-subject and by-item random intercepts and slopes varying across subjects and items. For each pair of models, the results of the likelihood ratio test were used to evaluate whether inclusion of additional random-effects parameters provided a better fit to the data, so that more complex models were excluded only if the p-value for the significance of the difference between the two models was above 0.2 (cf. Matuschek et al. 2017). Posthoc planned comparisons were performed as Tukey’s estimations using the multcomp package in R. Graphical representations of effects were plotted using the effects package (Fox & Hong 2010).

5.2 C-test

Figure 4 summarizes the c-test results. The percentage of correct reconstructions for the monolingual groups varied in the range between 53–80% (Italian) and 66–76% (Slovenian). The success rate for the bilingual group varied in the range between 48–81% (Italian) and 47–63% (Slovenian). Linear regression models revealed a significant interaction between the language status of participants and their age in both Italian (F = 3.21, p = 0.045) and Slovenian (F = 4.67, p = 0.011), bilinguals performing worse than monolinguals in both languages: the discrepancy persists through the 9 and/or 11 year old groups, and phases out in the 13 year old group. This is consistent with the generally known limitations concerning lexical competence in bilingual population (see Sections 1 and 3.4). Nevertheless, bilinguals (tested in their non-dominant language) never performed at less than 65% success of the monolingual population. Together with the early AoA, we take these results to suggest a level of linguistic proficiency sufficient for testing the impact of bilingualism on pragmatic abilities.

Figure 4

Results of the c-tests for each language group.

5.3 Pre-processing the data from the main task

At the pre-processing stage, the data from the main task were cleaned using the following criteria: i) correct responses to comprehension questions above 85%; ii) close fit to the age criterion, and iii) performance on the language ability test. Data from 4 participants was removed due to lower scores of control responses. The data from 5 children and 1 adult was removed as outliers with respect to criterion ii). Finally, we excluded 2 child participants who showed inability to understand the task in the language ability test. This left the data from 175 children and 41 adults for further statistical analysis. Table 1 shows distribution of participants per group after cleaning.

We entered the following measures as fixed factors in our models: i) GROUP (monolingual, bilingual); ii) CONDITION (LP; MP; MP-Neg); iii) AGE (9,11,13, adults); and iv) LANGUAGE (Italian, Slovenian). Treatment coding of factors (default in R) was used whereby the Italian language, bilingual group and Condition LP were assigned reference values. The data from the control group of participants who were over 18 years of age were uniformly coded as adult.

5.4 Monolingual adults

The percentages of correct answers per language and condition are shown in Table 2.

A model fit to the adults-only subset of the data revealed a main effect of factors LANGUAGE (χ²(1) = 6.72, p = 0.009), CONDITION (χ²(2) = 59.11, p < 0.0001) and their interaction (χ²(2) = 46.36, p < 0.0001). Post hoc pairwise comparisons in the form of Tukey estimations revealed a significantly higher rate of felicitous responses given by the Slovenian speakers compared to those given by the Italian speakers in condition LP (Estimate = 3.04, SE = 0.93, z = 3.26, p = 0.01) as well as condition MP-Neg (Estimate = 2.19, SE = 0.60, z = 3.59, p = 0.003), whereas there was no significant difference in response rates in condition MP (Estimate = –1.28, SE = 0.73, z = –1.75, p = 0.50). Within the Italian-speaking group, performance on condition LP and condition MP differed only marginally (Estimate = –1.522, SE = 0.53, z = –2.875, p = 0.061), whereas within the Slovenian-speaking group, performance on condition LP was higher than performance on condition MP (Estimate = 2.814, SE = 0.77, z = 3.651, p = 0.003). In addition, within the Slovenian group, there was no significant difference in performance on condition MP and condition MP-Neg (Estimate = –0.21, SE = 0.37, z = –0.56, ns), whereas, within Italian, performance on these conditions differed (Estimate = 3.26, SE = 0.50, z = 6.44, p < 0.001). These contrasts are illustrated in Figure 5.

Figure 5

Interaction of factors LANGUAGE and CONDITION in (monolingual) adult controls, given in estimated probabilities of correct answers.

5.5 Children: Raw data

Table 3 summarizes children’s raw per group results across all three conditions broken down also by language and bilingualism status.

Within the children’s population, our constructed models revealed no main effect of AGE (χ²(2) = 3.36, p = 0.18) and no interaction with any of the three other factors (p > 0.10). We also did not find an age effect when sampled across children and adults (χ²(3) = 4.86, p = 0.18). Put differently, children tend to produce a comparable ratio of targeted answers across conditions and groups. Factor AGE was then excluded from further analyses.

5.6 Children: Models and estimated contrasts

The model fit to the children’s sample data revealed a robust main effect of CONDITION (χ²(2) = 83.93, p < 0.0001). Tukey’s planned comparisons confirmed a significant difference between estimated responses on each of the three conditions involved (p = 0.01 for the pair of conditions LP – MP-Neg; p < 0.0001 for the other pairs) across bilingualism and language groups. This factor thus emerges as a reliable predictor of the targeted responses. There was a marginal main effect of LANGUAGE (χ²(1) = 2.71, p = 0.09). No main effect of GROUP was found (χ²(1) = 0.65, ns). Furthermore, a significant three-way interaction of the factors CONDITION, LANGUAGE and GROUP was observed (χ²(7) = 109.65, p < 0.0001). The three-way interaction model is summarized in Appendix II and illustrated in Figure 6.

Figure 6

Interaction of GROUP, LANGUAGE and CONDITION based on the children data, given in estimated probabilities of correct answers.

To better understand the three-way interaction model and specific loci of the effects in the interaction terms, we constructed smaller two-way models, while keeping the third factor constant, and focusing on interactions that are likely to be of interest in the context of our present research questions. The results were the following. A significant interaction between GROUP and CONDITION was found across the LANGUAGE factor (χ²(2) = 45.30, p < 0.0001). An examination of the respective model revealed that for the bilingual group, the odds ratio of giving a correct answer to Condition MP increase by factor 1.67 (84 %) compared to the monolingual group across the two languages. Post hoc pairwise Tukey comparisons indicated that this increase is significant (Estimate = –1.21, z = –3.881, p = 0.001). In other words, bilinguals are more likely to give the targeted answer to Condition MP than monolinguals. This holds both for Slovenian and Italian. In contrast, the odds of giving the targeted answer to Conditions LP and MP-Neg were not significantly affected by bilingualism (Condition LP: Estimate = 0.45, z = 1.900, ns; Condition MP-Neg: Estimate = 0.50, z = 2.137, ns).

CONDITION also interacted with LANGUAGE across the GROUP factor (χ²(2) = 41.04, p < 0.0001). Inspection of the model revealed that the interaction is confined to the monolingual group, and, further, to negative condition MP-Neg that has a greater success rate in Slovenian than in Italian (Estimate = 1.68, SE = 0.28, z = 6.049, p < 0.0001), which implies increasing the odds of giving the targeted answer to that condition by factor 1.64 (or 83% probability) if the language is Slovenian, compared to Italian (Estimate = 1.08, z = 5.070, p < 0.0001).

Speakers of both languages performed similarly with respect to condition MP (Estimate = –0.35, SE = 0.28, z = –1.261, p = 0.207). Posthoc pairwise estimations with Tukey’s adjustment method revealed that performance on condition LP (assumed as the base reference condition in the model) and condition MP does not differ significantly either in Slovenian (Estimate = –0.118, SE = 0.19, z = –0.609, p = 0.99) or in Italian (Estimate = –0.345, SE = 0.29, z = –1.202, p = 0.83). We also find that the actual success rate on condition LP within the Slovenian monolingual group of children (around 85%) is on a par with that within the Italian monolingual group (88%) but is lower than in the Slovenian adult controls (99%), the difference being significant (Estimate = 3.191, SE = 0.88, z = 3.637, p = 0.003). In contrast, in Italian, performance on this condition does not differ between adults and children (Estimate = 0.349, SE = 0.369, z = 0.947, p = 0.93), being relatively low in both cases (88% vs 87%). We will return to this point in Section 6.

Within the bilingual group, LANGUAGE and CONDITION do not interact (χ²(2) = 0.932, p = 0.627). Slovenian bilingual children, similarly to monolinguals, performed worse than adult controls with respect to Condition LP (Estimate = 3.872, SE = 0.875, z = 4.425, p = 0.0001). In contrast with the monolingual group, however, bilinguals’ performance on condition MP is better than condition LP in Slovenian (Estimate = –2.079, SE = 0.37, z = –5.628, p < 0.0001) as well as Italian (Estimate = –1.924, SE = 0.37, z = –5.180, p < 0.0001). Performance on negative condition MP-Neg is on a par with Condition LP in Slovenian (Estimate = 0.174, SE = 0.24, z = 0.734, p = 0.97) as well as in Italian (Estimate = 0.498, SE = 0.24, z = 2.088, p = 0.29).

Finally, there was also an interaction between GROUP and LANGUAGE across the factor CONDITION, confined to Condition MP-Neg (χ²(1) = 17.48, p < 0.0001). There was no significant interaction within Condition LP or Condition MP (all p > 0.10). Post hoc pairwise comparisons revealed that Slovenian was the language in which the odds of giving a felicitous judgment on condition MP-Neg were lower by factor 1.63, or 84% probability, for bilinguals than for monolinguals. In contrast, within Italian, felicitousness was not affected by bilingualism.

6.1 Adult controls

The results obtained from the adults were intended to provide a comparison frame for our tested children’s pragmatic knowledge. The null hypothesis was that both Italian and Slovenian-speaking adult participants perform at ceiling on the lexical presupposition Condition LP and Condition MP. Given the results in Stateva & Stepanov (2021), we expected that performance on condition MP will approximate that on condition LP in both tested groups, though not exceed it. The results we obtained largely confirmed this hypothesis: in neither tested language performance on condition MP exceeds that on condition LP. The performance of monolingual Slovenian adults on condition LP (about 99%) provides an indirect reference point for the 7-year-old children in the (2021) study which performed at (estimated) 97% success on that condition. This comparison reinforces the conclusion that the children in that study were quite close to the ceiling performance, hence near the end of the acquisitional path with respect to the ability to infer lexical presuppositions.

Furthermore, in the Slovenian-speaking group, performance on condition LP is better than that on condition MP, but still conforms with the predictions of the hypothesis that knowledge/ability to compute MP-related inferences is contingent on the ability to derive lexical presuppositions. In the Italian-speaking group, performance on both conditions is comparable, but performance on condition LP was somewhat lower than that in the Slovenian speakers. This lowering of ceiling performance in the Italian group compared to the Slovenian adult group appears surprising at first glance (see below for a possible explanation).

As for Condition MP-Neg, given that Neg-raising is available in Italian and not in Slovenian (Section 4.3.2), we predicted that Slovenian adults provide a comparable amount of target answers on Conditions MP and MP-Neg since both these conditions test sensitivity to MP. On the other hand, the alternatives in Condition MP-Neg in Italian are not truth-conditionally equivalent when a participant interprets the pensare (‘think’)-sentence with a negated embedded rather than matrix predicate. Under such interpretation of the Neg-raising verb pensare, the choice between pensare- and sapere- alternatives is not affected by MP and, therefore, no prediction within our set of assumptions is possible. Our predictions regarding Condition MP-Neg were borne out. The rate of target answers on Condition MP-Neg was comparable to that of Condition MP for the Slovenian speakers. In Italian, participants provided significantly less target answers to Condition MP-Neg which is in line with the hypothesis that Neg-raising dissociates the task in Condition MP-Neg from MP.

6.2 Child participants

In light of the finding reported in Stateva & Stepanov (2021) that age does not affect success in providing targeted responses across conditions, we expected that age would not affect performance on the MP-related conditions in the present study either. In line with this prediction, our results revealed no main effect of age and no interaction with the other manipulated factors. Performance on conditions LP and MP in our experiment was similar within the monolingual Slovenian group, and the actual (and predicted) success rates on these conditions (Condition LP: 85%, Condition MP: about 90%) are also on a par with monolingual Italian children’s success on the same conditions (88% and 90%, respectively). This converging pattern across the two different language groups, in our view, provides strong support for the hypothesis concerning acquisition of MP being contingent on acquisition of lexical presuppositions.

Consider now children’s performance on the MP-related conditions. Earlier we argued, following a number of previous findings, that adherence to MP requires competence about evaluation of alternatives and competition resolution and we linked that competence to the general cognitive functions of executive control and inhibition. On the hypothesis that bilingualism positively affects parts of the Executive Control system that are also relevant to language processing, we predicted that children’s bilingualism will interact with factor Condition. More specifically, we expected an advantage for the bilingual participants in their success rates with respect to Condition MP. The results confirmed that prediction. Bilingual participants performed significantly better on Condition MP in comparison to their monolingual peers, which provides an important piece of support to our hypothesis that bilingualism indeed affects sensitivity to MP.

The Slovenian monolingual children’s (actual and predicted) success rates on these conditions (Condition LP: 85%, Condition MP: about 90%) were somewhat lower than the reported ceiling rates in Stateva & Stepanov’s (2021) study in which 7-year old participant were tested. However, they are on a par with monolingual Italian children’s success on the same conditions (88% and 90%, respectively). A closer look suggests that a direct comparison of performance in the two studies may not be fully warranted. One source of potential difference is the mode of presentation: in the (2021) study, the verbal testing material was read to each child by an experimenter, whereas in the present study, participants read that material out loud themselves. More importantly, while in that study the children were tested on two conditions only, the present experiment included a third condition, MP-Neg, which increased the overall stimulus exposure both quantitatievely by 33% (24 stimuli compared to 16) and qualitatively, because of the increased lingustic complexity of the entire task. It is possible that addition of this complex condition lowered the ceiling performance on the LP condition in both monolingual and bilingual children, and on the MP condition in monolinguals.

This, of course, begs another question regarding the top performance of our bilingual participants with respect to condition MP (about 98%), which is the only, but crucial, exception from the predicted pattern. In order to approach this aspect, we may want to return to the issue of the source of the potential bilingual advantage with respect to computing implicated presuppositions in the context of MP. As noted above, there are good reasons to believe that the enhanced cognitive functions pertaining to executive control and especially inhibition observed in bilinguals are relevant to their ability to evaluate different kinds of abstract alternatives from a given closed set (in particular, irrelevant alternatives are inhibited). In an experimental task where a speaker explicitly has to choose among two linguistic alternatives generated in the context of the <know, think> pair, deploying this enhanced evaluative ability may reasonably give the bilinguals a selective advantage compared to monolinguals. This may be just the kind of advantage we observe in our bilingual participants with respect to the MP condition. Furthermore, it is not surprising that the bilinguals’ level of performance on this condition is unaffected by the hypothesized task complexity effect, precisely because it pertains to evaluation of otherwise identical alternatives which represents a typical case of competition resolution, for which bilinguals presumably have an enhanced capacity. In contrast, the task complexity effect may still affect the bilinguals’ performance on the LP condition because, strictly speaking, the relevant forced choice does not involve otherwise identical alternatives: one of the alternatives, namely, the know-alternative, is always irrelevant (because of the presupposition failure as part of the condition design).

The only contrast that still remains unaccounted for concerns the seemingly lower performance of our monolingual Italian-speaking adult controls on condition LP, compared to their Slovenian counterparts. At this point we attribute this contrast to an artefact of our Italian stimulus material or participant pool and leave it to be clarified in further experimental research.

As for Condition MP-Neg which also tested sensitivity to MP, again, we could only make a prediction about the Slovenian data, given the difference between Slovenian and Italian with respect to Neg-raising as noted above. Similarly to Condition MP, we predicted that bilingualism will positively affect performance on Condition MP-Neg in Slovenian. Both Slovenian-speaking adults and Slovenian monolingual child participants performed very well with respect to Condition MP-Neg. However, our bilingual participants’ responses revealed an interesting tendency. In both of their languages, they demonstrated a consistent linguistic behavior with respect to Condition MP-Neg, namely, they gave a comparable amount of targeted answers in each language. That rate was lower from that of monolingual Slovenian participants (and similar to the rate of targeted answers on Condition MP-Neg provided by monolingual Italian child and adult participants). This suggests that our bilingual speakers analyzed both of their translational equivalents of think as Neg-raising verbs, consistent with the Italian, but not the Slovenian, language. This conclusion is strengthened by the fact that our bilingual children showed the high success rate on Condition MP among all tested groups, thus disproving a potential hypothesis that they lack sufficient knowledge of MP.¹⁰

In light of these findings, performance on Condition MP-Neg can be potentially interpreted as a case of what is known in the literature on bilingual acquisition as (morpho-)syntactic transfer, a phenomenon of cross-linguistic influence whereby, in the process of bilingual language acquisition, a morphosyntactic feature is transferred from one language to another if it has different values in the languages being acquired (see Jarvis & Pavlenko 2008 for an overview and discussion). Syntactic transfer has been studied both in bilingual children (Yip & Matthews 2000) and adults learning a second language (Gass 1980; Chan 2004). In our case one can speak of a transfer of the Neg-raising property from Italian to Slovenian. Indeed, negation and Neg-raising are morpho-syntactically encoded differently in Slovenian and Italian. More specifically, Slovenian and Italian differ with respect to the Neg-raising parameter, the latter being a Neg-raising language like English, and the former not (cf. Section 4.3.2). It is therefore conceivable that our bilingual speakers wrongly assume, at least in some cases, that Slovenian is a Neg-raising language on the basis of transfer of the relevant part of their knowledge of Italian. As a result, treating Slovenian as a Neg-raising language leads to a set of negation-related inferences that would be expected from speakers of Italian, but not Slovenian. This is particularly likely to occur for those bilingual speakers who are more fluent in Italian than in Slovenian, or those for whom Italian is a dominant language. Previous research in bilingual processing showed that, the more dominant a language is for a bilingual, the more processing resources will be required to suppress that language while the person is using the other language, and the resulting interference from the dominant language slows a person’s processing and production of the weaker language (MacKay & Flege 2004). Future research in this direction should control for the language dominance factor as well as proficiency and their interaction with deriving MP-related pragmatic inferences related to know and think-type predicates.¹¹