Novel findings about syntactic processing

Summary and implications

In our studies on the comprehension of complex wh-questions using the questions-after-stories design with French-speaking 5–8-year-old children and adults (see Sections 3.1 and 3.2), two aspects of syntactic processing were examined: (a) the incremental parsing strategy of active gap-filling and (b) the processing of syntactic revision. While adults’

proficient abilities with respect to both aspects are broadly attested in the literature, less evidence exists concerning children and the few available evidence is often interpreted in the sense of immature syntactic processing skills. It turned out that the picture is much more complex because on the one hand, processing difficulties were found in both adults and children with certain syntactic structures, and on the other hand, children’s difficulties disappear under some conditions.

The first study (Lassotta et al., 2016; see Section 3.1) explored the interpretation of bi-clausal adjunct and argument wh-questions with a fronted wh-element in adults and children.

Incremental parsing was assessed by asking participants to answer ambiguous questions in which the wh-element could be associated with both the first (main-clause) verb and the second (embedded-clause) verb (e.g., À qui Marie a raconté qu’elle avait distribué des bonbons? ‘To whom did Marie tell that she had distributed some candy?’). Active gap filling would cause the parser to associate the fronted wh-element to the first available gap (i.e., of the main verb), resulting in a first/main verb attachment preference. Revision was tested by filled-gap questions which were identical to the ambiguous questions, but contained a disambiguating filled-gap PP blocking main-clause attachment (e.g., À qui Marie a raconté à son papa qu’elle avait distribué des bonbons? ‘To whom did Marie tell to her dad that she had distributed some candy?’). Thus, if the parser initially associates the wh-element to the main verb (due to active gap filling), this association then has to be revised to reach the ultimately correct analysis of second/embedded verb attachment.

Two main findings result from this study. First, French-speaking children and adults showed a strong main clause attachment bias when being presented with ambiguous wh-questions, let they be adjunct (85 % and 88 % main verb attachment, respectively) or argument wh-questions (95 % vs. 100 %, respectively). This suggests children’s use of an adultlike active gap filling strategy, although the second study (Lassotta et al., 2021, see Section 3.2) uncovered that their main verb bias can diminish under some conditions (especially in younger children), illustrating that other processes than the active gap filling strategy are involved in building the attachment as

well (see below). Second, filled-gap wh-questions gave rise to revision but also to misparsing in children and adults. While children mostly failed to access the grammatically correct embedded clause interpretation with adjunct wh-questions (88 % main verb attachment/misparsing), in which the filled-gap (i.e., the revision cue) is an optional constituent, they succeeded in about half of the argument wh-questions (52 % main verb attachment/misparsing), in which the filled-gap is an obligatory constituent. Thus, children appear to be sensitive to the nature of the revision cue, and hence to the argument structure, as revising is easier for them with obligatory filled-gaps in argument wh-questions (43 % increase of embedded verb attachment from the ambiguous to the filled-gap condition) than with optional filled-gaps in wh-adjunct questions (3 % decrease of embedded verb attachment), although misinterpretations remain frequent. Surprisingly, adults showed relatively low sensitivity to the presence and to the type of filled-gap, revising in about one fifth of the cases only and with both wh-question types alike (21 % increase of embedded verb attachment). Furthermore, misparsing frequently occurred in adults, not only in children, both with wh-adjunct (67 % main verb attachment) and wh-argument questions (79 % main verb attachment). This striking rate of misinterpretations was attributed to the option of placing wh-elements in-situ in French (e.g., Marie a raconté qu’elle avait distribué des bonbons à qui?

‘Marie told that she had distributed some candy to whom?’), which is the most common version of questions with embedded clauses in this language (Myers, 2007). In our acceptability judgment task, adults were found to prefer the in-situ over the wh-fronting version (Lassotta et al., 2016), suggesting that they may be prone to rely on distributional information (although they are typically argued to build on syntactic rules). The use of distributional/frequency information can in general increase parsing efficiency (of frequent structures at least), but in this case it may strongly push the parser to associate the wh-element within the same clause (here the main clause), thereby impeding revision towards the ultimately correct (embedded-clause) attachment. This finding is particularly interesting given that children showed less reliance on distributional information than adults (although they are typically argued to be influenced by frequency, within the constructivist approach at least). Instead, they seem to prioritize syntactic knowledge to establish the wh-attachment, as indicated by the effect of argument structure. It follows once more that frequency effects in sentence comprehension per se cannot be linked to immature syntactic representations or processing.

In the second study (Lassotta et al., 2021; see Section 3.2), children’s and adults’

interpretation of bi-clausal argument wh-questions was again examined, with a finer assessment of children’s behavior, examining 5–6-year-olds independently of 7–8-year-olds, with the aim of identifying possible developmental trajectories. The same questions-after-stories procedure as in

Lassotta and colleagues (2016) was used as well as the same questions, but with a light main verb (dire ‘say’) instead of the previously used heavy main verbs in order to reduce the strong main verb bias and thereby possibly facilitate revision. Additionally, measured participants’ cognitive control abilities were measured to explore whether they relate to revision, as argued by a number of research groups (e.g., Mazuka et al., 2009; Novick et al., 2005; Omaki & Lidz, 2015).

This investigation led to three major findings. First, when parsing ambiguous wh-questions (e.g., À qui Marie a dit qu’elle avait offert des chocolats? ‘To whom did Marie say that she had offered some chocolate?’), adults and children aged 7–8 years, but not 5–6-year-olds, were found to preferably attach the fronted wh-element to the first available gap (94 %, 68 %, and 40 % main verb attachment, respectively), rather than the second, indicating an incremental parsing strategy of active gap filling. Hence, our previous conclusion on the presence of active gap filling in 5–8-year-olds (Lassotta et al., 2016) needs to be revisited because (a) the main verb bias disappears with light verbs and can thus be achieved not only by applying this incremental parsing strategy used but also by relying on verb semantics (heavy main verbs strongly attracting wh-attachment), and (b) active gap filling becomes stronger with increasing age, as evidenced by the inspection of narrower age ranges. Second, when parsing filled-gap questions (e.g., À qui Marie a dit à sa maman qu’elle avait offert des chocolats? ‘To whom did Marie say to her mom that she had offered some chocolate?’), older children showed a similar rate of revision as adults, higher than younger children (63 %, 62 %, and 22 % embedded verb attachment, respectively), although a substantial rate of misinterpretations remained. Third, the ability to revise varied substantially between participants and was significantly and selectively linked with cognitive control abilities measured with an N-back task, namely inhibition and updating, but not with switching, perceptual inhibition or spatial working memory tested via a Dimensional Change Card sorting task and the Corsi task. The stronger the participants’ cognitive control in terms of inhibition and updating, the better is their ability to revise.

In light of the evidenced selective link between syntactic revision and inhibition as well as updating, I deduced that cognitive control comes into play as follows: revision requires to encode the revision cue (updating), to undo the initial attachment of the wh-element to the first verb (inhibition), and to integrate the subsequently arriving elements of the sentence (here the embedded clause) while retrieving the past linguistic material (the wh-element) and refreshing the mental representation with the newly built parse (updating). This shows the complexity of the revision process and the processing steps that can potentially fail. For example, if updating skills are insufficient to integrate the revision cue (here the filled-gap) in the ongoing analysis, the parser would be stuck with the initial attachment. Also, a predominant initial interpretation could hinder

revision if inhibition skills are not efficient enough to suppress it. Hence, if revision is too demanding and/or cognitive control skills are insufficient, misinterpretations like those observed in adults (and in children) can arise.

Both wh-question studies taken together, it appears that (a) not all children perform as adultlike in active gap filling as previously thought and (b) even adults perform not as adultlike in revision as one might imagine. With argument wh-questions, they ended up even more often with an ungrammatical parse (32 % with light verbs and 79 % with heavy verbs) than children aged 5–8 years (11 % and 52 %, respectively). The high rate of misinterpretations of filled-gap wh-questions in adults may not only be due to their in-situ preference over wh-fronting (due to priority reliance on distributional information), but also to their initial interpretation (due to active gap filling) being too strong to be crossed out by the cognitive control resources that this process requires. Hence, cognitive control appears to play an important role in syntactic processing in both children and adults and should therefore be taken into account in theories of language development and parsing.

Opening perspectives for future research

Thanks to working in inspiring multidisciplinary teams and collaborating with different stimulating research groups, many colorless green ideas are still sleeping furiously in my mind. I would like to present some of them here, which are closely connected to my dissertation studies, in order to initiate further research projects.

Proposal IV: Wh-question follow-up study

It is thinkable to replicate the last questions-after-stories task with argument wh-questions (Lassotta et al., 2021) but collecting eye-tracking data in addition to the verbal response (i.e., the parsing outcome) providing more direct measures of sentence processing mechanisms (i.e., online parsing). Eye-tracking data could shed light on the reason why the ultimately correct interpretation could not be reached: (a) because revision failed so that no alternative parse was generated, which would be reflected by a looking preference to the main-clause scene illustrating the inappropriate interpretation, or (b) because revision did take place, as reflected by a looking preference to the embedded-clause scene illustrating the appropriate interpretation, but the initial parse was still lingering and interfering too strongly to be rejected. Importantly, looking patterns could further

be used to examine the link between the ongoing processing steps of revision and cognitive control components.

Furthermore, there is a latent variable in all our data sets which could unfortunately not be considered because of the restricted number of participants per subgroup: the participants’

language status (mono- vs. multilingual). It would be interesting though to inspect the potential link of language status with parsing as well as with cognitive control. Multilinguals differ from monolinguals in terms of cognitive control, as has been widely attested by the Bialystok group for instance (see Bialystok, 2011, for a review). But the prevailing conception of a cognitive control advantage in multilinguals has also received critique arguing that it solely results from a publication bias (de Bruin et al., 2015). Hence, further investigations are worth examining potential differences between mono- and multilinguals. In line with Bialystok’s work, it seems plausible that multilinguals dispose of higher cognitive control abilities than monolinguals, due to their constant practice in changing languages, which implies inhibiting the currently irrelevant language(s). Multilinguals could benefit from these enhanced cognitive control skills and reach revision more easily by effectively inhibiting a currently irrelevant interpretation/representation.

Proposal V: Training study

Syntactic revision appears to be linked to cognitive control. This link has also been demonstrated in training studies with adults and interpreted as a causal relationship in that domain-general cognitive control positively influences language comprehension (and not the other way around; Hussey et al., 2017; Hussey & Novick, 2012; Novick et al., 2013). Given that the link holds for adults and children alike, it would be ingenious to examine this causal influence within a training study with children as well. I propose to test if there is a cognitive control training effect on (untrained) revision performance in filled-gap wh-questions in children aged 5–12 years (time of major cognitive control maturation; Davidson et al., 2006). Our N-back task would have to be slightly modified for this purpose in order to create (a) a performance-adaptive N-back because the task difficulty must evolve, i.e., adapt to individual performance, for the training to be efficient (Hussey et al., 2017), and (b) multiple versions of the game (introducing different themes or goals for example) so that the training stays interesting over time and engages the participants.

If the N-back training turns out to be effective, i.e., leads to improved comprehension performance, re-tests after 3, 6, and 12 months could evaluate the duration of the transfer effect, i.e., the long-term benefit of the training. If indeed, cognitive control enhancement causes better

comprehension of complex sentences, it can also help comprehension in everyday life, where we frequently encounter sentences that involve long-distance dependencies and therefore require working memory updating to encode and retrieve long-distance elements (e.g., wh-questions, object relative clauses, backward anaphora, and topicalization). Plus, children’s inhibitory control skills were found to be linked to the ability to suppress their own perspective to be able to adopt their communicative partner’s perspective, thus relating cognitive control to pragmatic skills in communication (Nilsen & Graham, 2009). Hence, cognitive control appears to be beneficial to language use and communication in various respects.