Null objects in BP have been described in the literature as an instantiation of the empty category pro (Farrell, 1990; Rothman and Iverson, 2013)¹, since they appear in strong and weak islands alike. Lopes and Santos (2014) point out that both VP-ellipsis and anaphoric null objects can occur in strong islands in BP, as illustrated in (1) and (2), respectively (from Lopes and Santos, 2014, p. 197):

(1)   A: -    O       João    soube    que    você    ia convidar

                  the     João    knew     that    you     were inviting

                  ele pra festa?

                  him to the party?

                  ‘Did John know you were inviting him to the party?’

        B: -    Não,    ele    morreu    antes de    eu    convidar    Ø.

                  no,       he    died    before    I    invited    [-]

                  ‘No, he died before I did it.’

(2)   Ela    comprou    o casaco    quando    experimentou    Ø.

        she    bought      the coat       when       tried                 [-]

        ‘She bought the coat when she tried (it) on.’

The distribution of null and overt objects is not entirely free, however. In order for objects to be dropped in BP, they must be 3rd person, as 1st, and 2nd person referents must remain overt. In addition, pragmatic felicitousness conditions and semantic feature constraints appear to limit their occurrence. Schwenter and Silva (2002) argue that, in order for the object to be null in BP, the referent must be inanimate or non-specific. If the referent is animate and specific, an overt pronoun or DP appears to be obligatory. The specificity constraint is shown in examples (3–4) (from Lopes and Cyrino, 2005, p. 3) and the animacy constraint is illustrated in examples (5–6) (from Schwenter and Silva, 2002, p. 579):

(3)   [+animate,   +specific]

       O policial     insultou o preso antes de torturar

       The policeman insulted._3sg the prisoner before of torture._INF

        *___/ele.

        *___/him

       ‘The policeman insulted the prisoner before torturing (him).’

(4)   [+animate,   −specific]

       O policial     insulta presos antes de torturar

       The policeman insult._3sg prisoners before of torture._INF

       ___/them

       ___/eles.

       ‘The policeman insults prisoners before torturing (them).’

(5)   [−animate, +specific]

       Sabe a árvore grande que tinha na minha rua? A prefeitura

       know-_3sg the tree big that had on+the my street? the city

         derrubou Ø/?ela.

         hall knocked down she

       ‘You know the big tree that was on my street? City Hall

         knocked (it) down.’

(6)   [+animate, +specific]

       O cachorro da Ana adora ir na rua. Ela sempre

       the dog of+the Ana love._3sg go on+the street. she always

          leva ?^*Ø/ele para passear.

         take-_3sg he to walk

       ‘Ana's dog loves to go out in the street. She always takes him

         for walks.’

Phonetically unrealized objects in EP are also restricted to 3rd person accusative contexts. Early studies argued that the syntax of null objects in EP must be a topic-operator-variable structure as opposed to pro, most convincingly argued on the basis of data suggesting that null objects are patently ungrammatical in island contexts. If accurate, having only a topic-operator structure would indeed mean that null objects are precluded from island contexts because they cannot be bound by the topic operator in the matrix clause when necessarily crossing a strong island boundary (Raposo, 1986; Maia, 1997). Data that lead to this conclusion are exemplified in (7) (from Raposo, 1986, p. 382):

(7)  ^*O    rapaz    que    trouxe Ø agora    mesmo da       pastelaria

        the   boy      who   brought Ø now    just from+the   bakery

        era o teu afilhado.

        was the your godson

        ‘The boy who brought (it) right now from the pastry

        shop was your godson.’

In more recent work, however, Raposo (2004) revises his initial stance, and argues that sentences such as (7) are (marginally) acceptable in EP, and therefore, at least some null objects in EP are instances of pro as is the case in BP. According to Raposo (2004), while null arguments within strong islands are not completely ruled out, they are not preferred whereas the null object is highly preferred in simple clause contexts.

It has also been discussed that, unlike what was shown for BP, animacy constraints do not seem to delimit null objects in otherwise possible syntactic environments in EP (Costa and Duarte, 2001; Costa et al., 2009). Since the object referent in (8a) is [−animate, +specific], this sentence is grammatical in both EP and BP; however, (8b) is not possible in BP because it is [+animate] and [+specific], but completely acceptable in EP (from Costa and Duarte, 2001, p. 5):

(8a)  A: E     este  carro?

             and   this   car

             ‘What about this car?’

        B:  O    Zé      quer   saber   quem comprou ec.

             the   zé       wants know  who bought ec

             ‘Zé  wants  to       know  who bought (it).’

(8b)  A: E     a Maria?

             and  the Maria

             ‘What about Maria?’

        B: O     Zé   quer      saber quem     beijou ec.

             the    zé   wants    know              who kissed ec

             ‘Zé wants to know                     who kissed (her).’

However, recent work by Duarte and Costa (2013) acknowledges that animacy effects on object drop can also be found in EP in limited contexts. These authors argue that, if the antecedent is within the same sentence, the object can be dropped if inanimate, as shown in (9), but if animate, dropping it is either marginally acceptable or ungrammatical, as illustrated in (10):

In addition, Duarte and Costa (2013) argue that some EP speakers allow for null objects within island contexts, provided that the referent is inanimate, as shown in (11a), but not with animate referents, as can be seen in (11b):

(11a)  A –   E então, o carro novo?

                   and so the car new

                   ‘So, what about the new car?’

          B –   A minha mulher está furiosa porque comprei

                   the my woman is furious because bought_1PSG

                   Ø sem ela saber.

                   [−] without she know_INF

                   ‘My wife is furious because I bought (it) without her

                   knowing.’

(11b)  A –   E então, a Maria?

                   and so the Maria

                   ‘So, what about Maria?’

          B –   ^*A minha mulher ficou furiosa porque eu beijei

                   the my woman became furious because I kissed_1PSG

                   Ø na festa.

                   [−] at+the party

                   ‘My wife became furious because I kissed (her)

                   at the party.’

Although this chapter deals with the nature of phonetically unrealized objects in BP and EP, our analysis will focus on how speakers interpret the differences between null and overt object conditions. While it is true that overt objects are the only other default choice—aside from null—, they typically surface differently in the two systems. While EP speakers make use of clitic pronouns in accusative contexts, BP speakers choose strong pronouns, as illustrated in (12) (adapted from Silva, 2015, p. 21):

(12)

As a replacement for the overt DP a Diana “Diana” in (12a), the strong pronoun ela “she” is chosen in BP, as shown in (12b), whereas EP speakers select the clitic a “her” instead. These clitics in BP are limited to written formal register and do not surface in colloquial speech (Montrul et al., 2011). EP licenses preverbal clitic placement in certain syntactic environments, as in (12c), but shows a higher preference for postverbal clitics, as in (12d) (see Madeira, 1992; Barrie, 2000 for discussion). These differences may not have a direct impact on the speakers' choice between null and overt pronouns, as this choice is arguably determined by the semantic and syntactic constraints previously discussed. However, they are especially relevant for a better understanding of our experimental design and the discussion of our results.

The relevant comparative facts regarding null object distribution in BP and EP are summarized in Table 1:

We have already alluded to the three groups participating in the experiment presented in this study. In Table 2 we provide details on their make-up and backgrounds.

The control groups (BPC and EPC) were recruited via social media, networks created by the main author, and collaboration of universities in different regions of Brazil and Portugal. Participants filled out a questionnaire, where they reported their age, age of arrival in Portugal (thus length of EP exposure) and various questions related to a self-assessment of frequency of BP/EP usage. As shown in Table 2, though the target group reported using EP more often than BP, their L1 usage was still quite high, which means that both languages are frequently activated. This frequency was estimated based on their answers to the following question: 'Taking into account the Portuguese language only, what option best describes your linguistic scenario?'. The options were the following, and the values we attributed to them are shown in parentheses.

The target group was tested in and around the city of Lisbon. All participants had normal or corrected vision and normal hearing.

The experiment was designed to test the subjects' interpretation of null vs. overt accusative objects. There are two versions of the experiment—one in EP and one in BP—which differ in their adjustment with respect to lexis, phonology, and morpho-syntax. The bilingual groups took both versions and the controls took only the version corresponding to their L1. We used an Acceptability Judgment Task (AJT), by which participants judged the acceptability of sentences on a Likert scale of 1–6. Each sentence was preceded by a context to ensure its plausibility.

Experimental items consisted of 80 items—40 items testing the effect of the differences between null and overt object pronouns and 40 fillers which served as target items for another study—and 20 random fillers to ensure equal distribution of acceptable and unacceptable items for both versions of the task. The target items were divided into eight conditions with five items each, as illustrated with examples from each version in (13–20):

(13) null animate in islands (NAI)

(14) overt animate in islands (OAI)

(15) null inanimate in islands (NII)

(16) overt inanimate in islands (OII)

(17) null animate in simple clauses (NAS)

(18) overt animate in simple clauses (OAS)

(19) null inanimate in simple clauses (NIS)

(20) overt inanimate in simple clauses (OIS)

This division was made to include different variables that can be analyzed simultaneously. Hence, we were able to test both animacy and island effects, which are expected to have an impact on the speakers' choice of null vs. overt pronoun in both languages. As can be seen in the sample test items, each version contained the appropriate choice of pronoun for that system—strong pronouns in the BP version and clitic pronouns in the EP version. This was done to ensure that participants would be judging sentences which are natural in spoken language, as the clitic choice is not the preferred option for Brazilians, and the strong pronoun is never selected by EP speakers. This also allowed us to check whether their overt pronoun preferences have undergone cross-linguistic influence, in both directions.

This task was built on an online platform called SurveyGizmo, which allows the user to create and design experiments with pictures, audio, and other media. Each test item was shown on a computer screen with a simultaneous audio recording of the context and the target sentence, in order to enhance the different modes triggered in each testing session (BP-mode vs. EP-mode). A male and a female voice were used for each version, all native speakers of each respective language. The recordings were counterbalanced such that for half the items, a male voice asked the context question and a female voice answered, and vice-versa for the other half. This was done to ensure that the participants were able to distinguish the context from the test sentence and express their preference considering only the latter.

All items, including fillers, were randomized to avoid priming. After reading and listening to the context and the target sentence, the participants were instructed to judge the sentence based on the scale placed immediately below it. Each point on the scale was distinctly labeled to ensure full understanding of their distribution. The scale used in this task is detailed in Table 3.

Once the participants had made their choice, they clicked on the button Continuar (Continue) to move on to the next item. All of their choices were automatically registered online after each click. Figures 1, 2 illustrate screenshots of a random item from the BP and the EP versions respectively:

The semantic and syntactic constraints in the null object distribution patterns in the two languages give rise to potentially different preferences by the target group as a result of interference due to intense exposure to EP, since the monolingual choices are geared by preference rather than grammaticality. This task helps measure the extent to which cross-linguistic influence takes place, and whether it is bidirectional (BP⇔EP), or unidirectional (BP⇒EP or vice-versa).

The most accurate way to check if these speakers are indeed bidialectal bilinguals is to test them separately in BP and EP. Therefore, the L2ers were tested twice, either first in BP, then EP, or the reverse, by native speakers of each variant. Grosjean (1998) has shown that bilinguals display different language modes in their everyday lives (see Grosjean, 1998, 2008 for discussion). In other words, depending on their interlocutor, speakers tend to switch from one language mode to another, even resorting to language mixing such as code-switching and borrowing (Grosjean, 1998). The two versions of the task were very similar, but adjusted for vocabulary distinctions between the two languages. While it is true that the participants all live in Portugal, it may not necessarily be the case that they interact with speakers of both variants to the same extent. Therefore, we included a mode-trigger rapport at the beginning of both sessions. The native EP speaker who conducted the EP version of the tasks started the sessions with general questions about what they liked most about Portugal, e.g., music, films, food, and so on. When tested in BP, they were asked about what they missed from their home country and what sort of connection they still have with Brazil, such as how often they visit, whether they participate in Brazilian events in the area, and so on. After 5 min of chatting, they were considered to be in the mode in which they were about to be tested.

The statistical analysis used for this experiment consisted of mixed-effects models with condition and group as fixed effects. We ran several models in order to consider all variables in our comparisons. First, we look at how the groups interpret the difference between each of the four null conditions and their overt counterparts. We then check for effects of semantic constraints (animates vs. inanimates) and syntactic environment (simple clauses vs. islands). The tables we include in the Appendix (Supplementary Materials) indicate the relevant lines of the models of mixed effects linear regression of all variables analyzed.

BPCs have significantly different values in all four comparisons (see Appendix Table 5 in Supplementary Materials). L2ers do not show a significant distinction between NII and OII in BP-mode (p = 0.686), or between NIS and OIS in EP-mode (p = 0.077), but all other comparisons show a clear null vs. overt difference for this group in both modes (p < 0.05). Like EPCs, BPCs also interpreted all four null conditions to be different from their overt counterparts (and thus assigned different values to them). The spread of the difference between each null and overt context for each of the groups tested is illustrated in Figure 5.

Even though BPCs and EPCs are aware that they should assign different values to sentences with null objects and to sentences with overt objects, the spread of this difference in values is significantly different across the two control groups in all four contexts (p < 0.05), (see Appendix Table 6 in Supplementary Materials).

We also found that, in contexts with animate referents within strong islands (NAI and OAI), L2ers interpreted the null vs. overt distinction in BP-mode the same way as they did in EP-mode. However, for the other three environments, they showed statistically different behavior across the two modes, especially with inanimate referents (see Appendix Table 7 in Supplementary Materials). In BP-mode, L2ers only behaved like BP monolinguals regarding the null vs. overt distinction in contexts with inanimate referents in simple clauses (NIS-OIS) (p = 0.104). In EP-mode, L2ers patterned with BPCs in contexts with inanimate referents in strong islands (NII-OII) (p = 0.091), being significantly different from BP controls in all other comparisons. In both modes, L2ers behaved differently from EPCs with respect to how they interpreted the differences between null and overt in all four environments (see Appendix Table 8 in Supplementary Materials).

Effects of animacy were found for all groups. Participants' assigned values to contexts with null objects are significantly different in items with animate referents than in items with inanimate referents, both in simple clauses and in strong islands (NAI-NII, NAS-NIS), as shown in the Appendix Table 9 in Supplementary Materials. With respect to the syntactic environment, Table 10 in the Supplementary Material illustrates that all groups show a statistical difference between null objects in strong islands and null objects in islands when the referent is inanimate (NIS-NII). BPCs also displayed statistical differences with animate referents (NAS-NAI). This did not seem to be the case for L2ers in either mode and EPCs, for whom the syntactic environment does not affect their judgment on null objects with animate referents.

Lastly, we ran a few additional models (see Appendix Table 11 in Supplementary Materials) focusing solely on the overt conditions, in order to determine whether the morphosyntactic status of overt pronouns—strong pronouns vs. clitic—had a significant effect on the L2ers' preferences. Our results show that L2ers gave significantly lower ratings to sentences with overt pronouns than the monolingual counterparts, in each respective mode (p < 0.01).

The fact that both BPCs and EPCs attributed different values to sentences with null pronouns vs. overt pronouns was not surprising, given that the contexts created took into consideration the variables that arguably determine the null object distribution in each language. The extent to which these two groups interpreted the null vs. overt distinction was not the same, which confirms that the reason why this spread was larger in EP than in BP must be linked to either semantic or syntactic constraints. In light of Schwenter and Silva (2002), we expected BPCs to prefer null objects in contexts with inanimate referents (regardless of syntactic environment). Indeed, we find an effect of animacy for BPCs, as they attributed higher values—though not categorically—to sentences with null objects when the referent was inanimate than to similar sentences with animate referents. EPCs also seemed to show animacy effects, which confirms the arguments made by Duarte and Costa (2013). In fact, when the two control groups are compared to one another, they showed statistically similar behavior with respect to how they interpreted the animacy differences in the contexts given. We conclude from this that the distribution of null objects in BP and EP is not determined, but rather influenced by the [± animate] status of the referent, since the results indicate a general preference rather than a categorical grammatical vs. ungrammatical distinction.

With respect to how the syntactic environment may influence the participants' choices, we expected BPCs to show no effects, as null objects can freely appear within strong islands—provided that the animacy constraints are not violated—, as shown in Rothman and Iverson (2013), Lopes and Santos (2014) and others. Conversely, EPCs are expected to use the syntactic environment as a determining factor for their choice of null vs. overt, in light of Raposo (1986), but in combination with the animacy status of the referent (Raposo, 2004; Duarte and Costa, 2013). Our data show that BPCs display island effects, contrary to what we expected, as the difference in mean values between the contexts with null pronouns (both animate and inanimate) in simple clauses and the same contexts in islands is statistically significant. This suggests that null objects in BP are more likely to occur in contexts with simple clauses than in contexts with strong islands, especially if their referents are inanimate. Therefore, the syntactic environment seems to also have an effect on whether or not the object is likely to be dropped in this language.

EPCs do not make a distinction between these two syntactic environments when the null pronoun has an animate referent—judging both NAS and NAI as equally unacceptable (below the threshold of 3.5)—, but do show a distinction between them when the referent is inanimate, as they judged NIS acceptable but NII unacceptable, as predicted. In other words, the data confirm that null objects in EP are more likely to occur in simple clauses than in strong island contexts, but for inanimate referents only, as the null-object contexts with animate referents were judged unacceptable despite the syntactic environment. When compared to BPCs, the only environment where EPCs show significant differences regarding the syntactic environment was in contexts with null pronouns and animate referents (NAI-NAS), which suggests that the syntactic environment has a stronger effect in EP than in BP. As we pointed out, while the syntactic and semantic constraints appear to be the same in the two systems, the way in which they surface differs, and these differences across the monolingual groups with respect to the syntactic environment serve as evidence for this.

To summarize the comparison between the control groups, we conclude that, even though both the syntactic environment and animacy status appear to have an effect in both BP and EP, the surface distribution of null vs. overt pronominal objects in the control groups is distinct because of the order in which the constraints apply. Our data show that, in EP, the animacy status applies first, and then the syntactic environment, but in BP this order is not clear.

Based on the differences between the control groups with respect to the null vs. overt distinction, we have the tools to discuss the L2ers' performance and the statistical comparisons we made. First of all, L2ers appear to differ significantly from themselves across BP- and EP-modes, except for environments with animate referents in syntactic islands (NAI-OAI). In the other three environments, the null vs. overt distinction for the L2ers was higher in EP-mode than in BP-mode, which reflects the behavior shown by the control groups.

The semantic and syntactic effects also seem to hold for this group. In both modes, L2ers assigned different values to contexts with null objects with animate and with inanimate referents, in both simple clauses and islands. Regarding the syntactic environment, this group also showed significant distinctions in both modes in contexts with null objects and inanimate referents (NII-NIS), but not in similar contexts with animate referents (NAI-NAS). When we consider the null vs. overt distinction, L2ers show significant differences to both control groups in almost all comparisons, except for contexts with inanimate referents in simple clauses (NIS-OIS), where they pattern with BPCs when in BP-mode, and in contexts with inanimate referents in strong islands, where they show BP-like behavior when in EP-mode.

In short, the syntactic environment and animacy status that determine the null object distribution in BP and EP are both at play simultaneously for the target group. Their interpretation of null vs. overt object contexts is highly dependent on these two factors, as it is for monolingual speakers of each language. However, the distinctions between these contexts are mostly interpreted in a way that is different from what was shown by the control groups. Nevertheless, L2ers still behaved BP-like in contexts with inanimate referents in simple clauses (when in BP-mode), and showed signs of the BP distribution when in EP-mode in contexts with inanimate referents in strong islands. No EP-like behavior was detected for these speakers in either mode. Moreover, with respect to overt object pronouns, L2ers gave significant lower ratings than both BPCs and EPCs in each respective mode, which indicates cross-linguistic influence in both directions. Since the clitic option is less preferred in monolingual BP, the lower ratings attributed by L2ers to sentences with overt clitics when in EP-mode can be interpreted as a result of BP=>EP influence. Conversely, sentences with overt strong pronouns were significantly less preferred by the L2ers in BP-mode, which suggests EP=>BP influence. With this in mind, we can link the data to the hypotheses we test in this study.

As discussed in Section Typological Proximity in the Context of L2 Processing and L1 Attrition, recall that several researchers have drawn a link between typological proximity and L1 attrition (e.g., Gürel, 2008; Schmid, 2011). Given the high level of proximity between BP and EP and the length of residence in Portugal of the target group, we hypothesized that these naturalistic L2 learners of EP should display some signs of EP influence in their native BP. As we have shown, the way in which L2ers perceived the differences between contexts with null objects and overt objects when in BP-mode was no longer BP-like, with the exception of one of the contexts (inanimate referents in simple clauses). While not entirely EP-like either, the behavior shown by L2ers in BP-mode indicates that they interpret the null vs. overt distinction differently from monolinguals. As shown in Figure 5, L2ers showed much lower coefficients of differences between the null and overt conditions than the monolingual controls. However, BPCs themselves did not distinguish between the two sets of conditions to the same extent that EPCs did, particularly in the NIS condition. In addition, L2ers in BP mode gave lower ratings to sentences with overt pronouns than BPCs. This can be attributed to the fact that strong pronouns, which are the default choice for most BP monolinguals, are significantly less acceptable to the target group. While it is true that they still judged the sentences as acceptable (well above 3.5), the significant difference between their judgments and the BPCs' judgments suggests a possible effect of EP grammar on their BP. We take this as evidence of cross-linguistic influence from EP to BP instead of a general effect of bilingualism.

In light of Hartsuiker et al. (2004), we understand that the lexical co-activation of the L1 should lead to its syntactic co-activation, and as a result, we expected the L2ers in EP-mode to display preferences similar to those of BP monolinguals. Miller (2014) and Hopp (2016), however, defend that the lexical co-activation of the L1 might actually inhibit the L1 syntactic structure, and consequently, L2ers are expected to display target-like performance instead, which would have been manifested if their preferences in EP-mode reflected those of EP monolinguals. We take advantage of the high level of typological proximity between BP and EP to test these two possible outcomes.

Our data show that, in EP-mode, L2ers do not quite reach target-like performance with respect to the EP null vs. overt object distribution, as they are statistically different from EP controls. While also different from BP monolinguals in three of the comparisons, they show BP-like behavior in contexts with inanimate referents in strong islands (NII-OII). We interpret this as an indicator that the BP structure is activated in these speakers' minds, despite the fact that they are in EP-mode. This suggests that, as shown by Hartsuiker et al. (2004), L1 syntax is co-activated with the lexical co-activation of the L1, which was expected given that these two languages share most of the lexicon. Unlike what was shown by Miller (2014) and Hopp (2016), L2ers were not able to fully inhibit their L1 syntax and thus did not reach target-like performance in their L2. Their L1 syntax, despite showing signs of attrition, remains active in the brain, enough to cause them to display some BP-like behavior, even when in EP-mode.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.