Third Languages Acquisition (TLA): Educational Multilingualism at Early Ages

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This is a potentially interesting and timely study of the early acquisition of a third language in an educational setting. However it is not publishable in its current form due to a number of major shortcomings.

The sections in the paper are misleading, as section 2 is called Materials and Methods, but contains both the theoretical background and a brief (but insufficient) description of the study itself. I recommend separating these into one section on the theoretical background, and one on Materials and Methods, in line with a standard IMRaD structure. The actual Materials and Methods section must be substantially elaborated, in particular in explaining the linguistic profiles and language learning contexts of the participants in much more detail.

The section on the theoretical background of and previous research on third language acquisition needs to be completely re-written. At the moment, it is rather unfocused, going back and forth between related but distinct issues such as the overall impact on bilingualism on attainment in a new language, the respective roles of L1 and L2 for influence on L3, the impact of age in language acquisition, and the benefits of learning an L3 on the prior languages. In many cases, studies showing results on different domains are presented as if they discuss the same issue, and in at least one case (Snow and Hoefnagel-Höhle), conclusions are misrepresented. See also comments in the manuscript. It is not clear how and why all the different issues of L3 acquisition are relevant to the present study, given that most of these issues (i.e., outcomes in L2 and L3, differences according to starting ages, etc.) are not addressed in the current study: only the impact of an additional language on the L1 is investigated here, so this should be the focus of the theoretical background. The starting ages of and exposure to the L2/L3 for the participants is very unclear, but it seems that if the authors think that exposure to these additional languages is massive enough to significantly impact the L1, theoretical background and previous research on child bi- and multilingualism may be more relevant than most L3 research where the L1-L2-L3 process is clearly sequential and focus is on outcomes in the L3.

It is also a major weakness that most references are at least 20 years old - the past two decades have seen a sharp increase in work on L3 acquisition and multilingualism, and this is not reflected in the paper. For example, at first, Hammarberg is cited as the only source arguing that the L2 has a privileged role for transfer, and later work by Bardel & Falk in this area is only mentioned in passing much later. There is also no mention that this argument is mainly made specifically for older learners who have also learned the L2 after puberty, which is less relevant to the current study - and, of course, the point is relatively moot given that the present study does *not* investigate L3 outcomes. The many more recent studies of what factors influence transfer from prior languages are not mentioned. If the authors believe the field of L3 acquisition is the most appropriate to contextualize their study, I strongly recommend starting by looking at the recent Cambridge Handbook of Third Language Acquisition (2023) for more updated work on L3 acquisition, but, again, I am not sure that this is the appropriate research field for this study.

The description of the linguistic profiles of the participants also is not sufficient; see also comments in the manuscript. My interpretation is that the trilingual experimental group consists of children who learned French as an L2 before English, while the control group has only learned Spanish and English, but this is very unclear from the manuscript, and there is no information about when and how they learned French. My interpretation also does not align with the statement in the methods section that the French learners constituted "a smaller number" while the experimental and the control groups are described as having 55 participants each in the Results section. In the methods section we are not given the necessary information about the number of children in each group, starting ages for each language, general proficiency in L2/L3, context of French acquisition, etc. Importantly, it is not entirely clear whether the participants are all true L2/L3 learners (i.e., only one real L1), or whether they/some of them may better qualify as 2L1 bilinguals with two native languages and/or heritage speakers of one or more of the languages. Given the crucial role of early childhood for acquisition processes, this distinction is of fundamental importance.

The analysis and presentation of results also is not very illuminating. Results are shown only in percentages and scores, with no statistical analysis. This makes it impossible to say, for example, whether a 5 percentage point advantage in one group over the other is meaningful. We are given the point difference between the groups on the various parts of the test, but since we have no idea how the test is scored and what the maximum possible score is for each part (and are only given the total maximum total score after the point differences are discussed), this is not very informative. It is also not clear what it means that participants "surpass" the test as long as their scores are above 75%.

The many figures showing scores per group per year also are not very meaningful: We know very little about the participants, how long they have been learning their languages, and what variation there is in various contextual factors within each group, and we are given very little information about within-group variation in performance, further obscuring the meaningfulness of between-group differences. The problem with assuming that small raw score differences must be meaningful is, for example, clearly illustrated in figure 2 where, if we are to take such small differences seriously, children see a *regression* in linguistic skills from age 3 to 4 in both groups. In the conclusion, the authors acknowledge that unexpected dips in performance may be due to small sample size; it seems to me that this issue may in fact explain all between-group differences in the study, rendering the results meaningless.

There is no real discussion, just a bullet pointed list repeating results; the implications of the study are thus very unclear. A few points that would belong in the Discussion are briefly mentioned in the conclusion, which is unnecessarily long and brings up new points not discussed before.

In short, while I believe that the data collected may have merit, given that the authors do mention having collected the appropriate background information about participants, the paper in its current form does not contribute to the field in a meaningful way. The authors need to better situate the study in the most relevant, and current, research, whether that be L3 research or child multilingualism research; they need to provide much more detail about the participants, their linguistic profiles, learning situation and other contextual factors, and data must be analyzed in a meaningful manner using inferential statistics to establish whether the small group differences can in fact be attributed to linguistic profiles rather than to the many other factors that certainly play a role. The findings then need to be properly discussed in light of relevant existing research.

Again, given that it seems that the authors have in fact collected the relevant background data, I believe this complete revision of the paper is possible, and the study would then contribute very useful knowledge about early child multilingualism.

See also further comments in the attached document.

 

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Third Languages Acquisition (TLA): Educational Multilingualism at Early Ages

This study deals with the acquisition of L3 by comparing it to the acquisition of L2 to see to what extend simultaneous learning of three languages can benefit or obstruct a typical/normal language development of the L1. Both the L2 and the L3 are considered FLs. The study is based on the results provided from the Navarre Oral Language Test-revised. It analyzes the scores from 110 L1 Spanish speakers whose L2 is either English or French. The results are classified in terms of the different competences included in the Test (Phonological, Morphological-Syntactic, Lexical-Semantic and Pragmatic), the age of the participants (3-6) and the L2/L3 condition (control and experimental). The results obtained show that the participants who had an L3 generally outperformed the L2 group indicating that the additional language benefits the oral language development.

 

General comments:

The main aim of the article is very interesting. It seeks to shed some light on the impact that the early L3 acquisition can have on the language development in general and on the difference between the L2 and L3 learners in particular.

However, the whole study is based on the results obtained in the PLON-R, which is a test used for cognitive assessment (mainly for impairment purposes). Since it analyzes different aspects of the language such as phonology, morpho-syntax, lexical-semantics, and pragmatic, it can also make sense to use it as an indicator of proficiency and development within the language acquisition. With that said, the analysis that the author(s) provide(s) has various issues that need to be addressed:

1. The analysis of the results is very vague, and it is not supported by any statistical analysis that could indicate whether the results are significant or not. In most cases only raw data is included and this makes it difficult to interpret the results.
2. There is no clear description of the participants. For example, in the case of the L3 participant group, what is their L3? The L2 participants have either English or French as their L2. How many have English? And how many have French? Why are they grouped together? If it is argued that language typology plays a role (see theoretical context), does it not make sense to divide these participants into two different groups as well. Or, if the sample of the L2 French group is small, exclude these participants from the study. Also, why is an L1 group not included as the control group? Why is the L2 the control group and the L3 the experimental group?
3. Once the scores of the participants are obtained, they are included and classified according to the scoring quality in table 1. However, these scores are not used for further classification of the participants. Mixing the participants that already show a delay with participants that are classified as “normal” obscures the results.
4. The result provided are generally either RS or STS scores and these are not further explained. For a more comprehensible overview of the data, at least percentages should also be provided and analyzed.
5. The figures provided should include axes (scales) that are unified. And these scores should also include percentages. The figures are very confusing and there is no consistency in the scales.

What regards the discussion, it is very simple and vague. It is structured as a summary of the results with a very simple interpretation that is repeated several times. There is no connection to previous studies mentioned or to what has been treated in any of the previous sections such as the “introduction” or “materials and methods.” The results should be analyzed in terms of the theoretical aspects argued in the theoretical background. This section needs to be expanded and improved considerably.

What regards the review topic, it is dense. Also in this case various issues need to be addressed with great attention.

1. The review topic contains a lot of ideas and characteristics related to multilingualism. These are classified in terms of relative topics in SLA and TLA (such as age, typological similarities of languages in contact, crosslinguistic influence) but the information within each section seems to be a simple enumeration of the studies and, very briefly, their main finding. This results in a lot of repetition and a lot of unclear and unconnected arguments.
2. The previous studies analyzed are not up-to-date. The newest study included in this manuscript dates back to 2014. Some of the reference included here below can provide a more recent view on the TLA and on the influence that the L2 has on the L3 (as the other(s) claimed has not been treated so far).

Eibensteiner, L. (2023). L3 acquisition of aspect: the influence of structural similarity, analytic L2 and general L3 proficiency. International Review of Applied Linguistics in Language Teaching, 61(4), 1827-1858. https://doi.org/10.1515/iral-2021-0220

Puig-Mayenco, E., González Alonso, J., & Rothman, J. (2020). A systematic review of transfer studies in third language acquisition. Second Language Research, 36(1), 31-64. https://doi.org/10.1177/0267658318809147

Stadt, R., Hulk, A., & Sleeman, P. (2020). L2 influence in L3 acquisition: The role of the L3. In Formal Linguistics and Language Education: New Empirical Perspectives (pp. 203-221). Cham: Springer International Publishing.

Llop Naya, A., Puig-Mayenco, E., & Paradís, A. (2024). The acquisition of Polarity Items in L3/Ln Catalan by speakers of English, Italian, Portuguese and Spanish: implications for L3/Ln development theorising and language teaching. International Journal of Multilingualism, 22(1), 53–75. https://doi.org/10.1080/14790718.2024.2367583

Pinto, J., & Alexandre, N. (Eds.) (2021). Multilingualism and third language acquisition: Learning and teaching trends. Language Science Press.

González Alonso, J., & Rothman, J. (2017). Coming of age in L3 initial stages transfer models: Deriving developmental predictions and looking towards the future. International Journal of Bilingualism, 21(6), 683–697.

3.  What is the purpose of including the selection on the resolutions and directives in the European Institutes since 1984? What information does this add to the objectives of this study? The fact that so many points are included and the fact that it is written in point form breaks the narrative. Consider eliminating this section or at least paraphrasing it into a very short paragraph.

4. The paragraph in lines 179-188 should include more updated studies.

5. Suggesting that L2 has the greatest impact on L3 (lines 231-232) needs to be further developed. This is one of the crucial points and it is treated here very lightly. Also, please explain how prior knowledge influences the L3 (lines 232-234). In addition, how can a study that is conducted in 2007 cite another study conducted 2 years later in 2009?

6. The paragraph in lines 235-240 includes vague and outdated references. More specific information is needed here, since it seems like a simple enumeration of studies.

7. The paragraph that starts in line 279 and ends in line 290 needs to be further developed. As it is, it seems like a mere summary of somewhat outdated references.

8. The section on “typological and functional factor” should be reorganized. It is vague and unclear as it is. It seems like a mere enumeration of studies and references with a very short summary of each article.

9. No clear distinction is made between foreign languages and L2. This needs to be clarified.

10. What regards references, these also need to be reviewed as there are many inconsistencies (for example, there are some doble brackets that are unnecessary, some italics are missing, the year of publication is sometimes included twice etc.)

 

Specific comments:

In general, the use of the acronyms and the full form is inconsistent. For example, in line 30 the author(s) write(s) “foreign languages (FLs).” The acronym and the full form are used interchangeably. In line 320 (an on more occasions) the whole form “foreign languages (FLs)” is used once again. Once the acronym is provided, it should be used throughout the whole manuscript. Please, review the use of the rest of the acronyms, since the same issue arises with, for example, Oral Language (OL) and Navarre Oral Language Test-Revised (PLON-R).

In the notes, the following issues should be corrected:

Note: i) Spanish should be capitalized. Maybe it could be a good idea to indicate that the Spanish acronym is being used.

Note: ii) instead of “sum total” it should be “total sum”

Note: ii) there is a comma missing in “i.e.” It should be “i.e.,”

Line 30: “necessitates” sounds odd in this context. Consider rephrasing.

Line 31: the use of the term “mother tongue” is somewhat obsolete nowadays. Consider rephrasing to L1 (first or native language) and correct it elsewhere.

Line 31: MT/L1 is the same thing. Consider deleting MT, since this term is obsolete. Also, what exactly is the difference between the L1 and MT/L1?  

Line 54: PLON-R is the Spanish abbreviation. Why is English not used here?

Line 57: “illuminating” sounds odd in this context. Consider rephrasing.

Line 60: it is unclear why this section is called Materials and Methods. Why is the theoretical context and the methodology in the same section. Consider separating.

Lines 86-89: these two sentences are somewhat unclear and should be rephrased. Also, a reference that support this information should be provided. 

Line 152: eliminate “specialist”.

Lines 192-194: consider rephrasing this sentence as it is unclear.

Lines 179-188:  some more recent studies should be included.

Lines 205-206: more recent reference alongside the “Snow and Hoefnagel-Höle (1978)” should be added.

Line 224: consider changing “influence” to “crosslinguistic influence”

Line 245: what is meant by “the degree of bilingualism”?

Lines 259: consider rephrasing “research on L1/L2/L3 transfers includes Cenoz (2001)” as it sounds odd as it is.

Lines 269-271: this is a direct quote, so the page number should be included in the references.

Line 275: why is it relevant to specify that it is “outside the Basque context”?

Lines 279-290: this paragraph needs to be further developed. As it is, it seems like a mere summary of somewhat outdated references.

Line 298: “CLI” is crosslinguistic influence not “typological or linguistic distance” 

Line 300:  “Most CLI research focuses on lexicon.” Who claims this? And how is this relevant for this study?

Line 309:  what is meant by “the foreign language effect?”

Lines 310-311: Please, clarify. Why is it relevant that they only highlight the role of the L2 in the L3?

Line 312-313: please, clarify.

Line 322: “normal development” should be changed into “typical development” in this case and throughout the whole manuscript. “Typical” is considered a more adequate term.

Line 323: clarify why L2 and FL are used interchangeably (here and elsewhere). 

Line 324 & 327: clarify why students and pupils are used interchangeably (here and elsewhere). 

Lines 235-240: includes vague and outdated references. More specific information is needed here, since it seems like a simple enumeration of studies.

Line 336: “age of the sample” sounds odd. Consider rephrasing.

Line 336: “age categories” sounds odd. Do you mean “age range”?

Line 377: “Demonstrates strong communicative competencies in oral language” according to which measures? Please, clarify.

Line 386-387: figure 1, the use of a pie chart is not very illustrative in this case. A total of a pie chart should be 100% and not 161%. And both legends should be identified (blue for the control group and orange for the experimental group).  Also, the title of the figures should summarize what the graph represents, and not what each color stands for. Correct elsewhere.    

Line 419: change “as illustrated in the following table” to “as illustrated in table 2” and do so elsewhere.

Line 427: percentages should be added to the RS and STS data.

Lines 434-439: this is repetitive. How is this different from what you have at the beginning of the general results section.

Line 441- 443: consider rephrasing as the wording is unclear.

Line 456: consider rephrasing.

Line 489: why is this figure different from the rest? What do the axes represents? Is the total score in this case 250? Please, clarify.

Line 491: “this figure” should be changed to “figure 6”

Line 493: to deal with “significant difference” a statistical analysis must be conducted.

Lines 496-498: this sentence is unclear. Please, clarify.

Line 499: no statistical analysis has been conducted for you to confirm this.

Line 507: is figure 8 supposed to serve as a summary? Why are the differences included in the figure? In this case, it represents percentages? If so, please explain this.

Line 512: what does “5 percentage points” really mean and how is it different from 4% in line 514. please unify and clarify .

Line 521 & 523: rephrase so that there is no specific point for analysis an another one for interpretation. As it is organized, it is very repetitive.

Line 521: “exhibits superiority” sounds odd and should be rephrased.

Line 522: “the control group performs better at ages 5 and 6.” My impression was that the analysis was always across groups and not within groups. Please, clarify.

Line 524: what is meant by “greater development”. Please, clarify.

Lines 529-530: how is the information provided in the interpretation different from the analysis? Please, clarify.

Line 544: “the experimental group shows greater evolution,” how can this been seen in your data? To deal with evolution you would need to compare the same participants over a period of time (that is, evolution is something that can be seen in a longitudinal study). 

Line 548: “As they advance in age,” once again it seems like you have conducted a longitudinal study and that is not the case. Please, clarify and rephrase.

Line 557: to deal with “significant difference” a statistical analysis must be conducted.

Line 580: the results are being interpreted in terms of interlanguage. No previous studies analyzed in the theoretical context mention interlanguage. Either, include specific studies on interlanguage that support your hypothesis or interpret your results in terms of the studies that you have analyzed previously.

Line 584: the results are also being interpreted in terms of “the critical period”. No previous studies analyzed in the theoretical context deal with the critical period. Either, include specific studies on the critical period that support your hypothesis or interpret your results in terms of the studies that you have analyzed previously.

Line 589-591: the fact that the sample is small is a limitation. Since a whole section on limitations is included, this should be treated there and not in the discussion.

Line 593-594: what does this add?

Lines 594-596: as this sentence is formulated, it sounds like there is a very big difference between the groups and that is not the case here. Please, clarify and rephrase. Also avoid the use of “superior” and “superiority.”

Line 603: consider rephrasing.

Lines 625-631: where can this be seen in your data? Please, clarify.

Line 650: what is a “meaningful profile”? Please, clarify.

Line 655: how can you analyze the mental age of the participants? How can you account for this? Please, clarify.

Lines 664-667: so, you do not even argue in favor of the validity of this test.. so, why run it? why base a whole manuscript on its results?

Line 670:  here reference is made to future research and not just the limitations. Please, clarify.

Line 677: consider changing “necessitating.”

Line 715: this manuscript is not a “thesis.”

Line 725: well, there are some studies that have dealt with the benefits of an early L3 acquisition. Some references have been included in this review.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I am afraid that I cannot recommend this paper for publication, because most of the fundamental problems that I pointed out in my previous comments remain.

The theoretical background has improved and now discusses child bi- and trilingualism. However, it seems that this literature review establishes that trilingual acquisition is not detrimental to development in either of the languages, and it is thus not clear from this review what the remaining research gap is that will be addressed. In particular, it is well established that the crucial factor in child language acquisition is exposure to the language in question, not the number of languages being acquired. It seems to me that exposure to Spanish, the language under investigation in this study, is essentially the same for children in both groups, while the group difference is in exposure to English vs. French. For that reason, I see no reason to hypothesize group differences in Spanish development, and the theoretical background fails to provide such reason.
- the relevance of the review of transfer/CLI in L3 acquisition remains unclear, as transfer/CLI is not addressed in the study itself
- Both in the abstract and in the research questions outlined there is mention of having learned a prior L2 as a benefit for learning an L3; there are, however, no such results presented (and immediately after the three research questions are presented, we are given only two hypotheses, none of which address this question.) 
- The issue of the unclear "smaller number" of students for whom French was L2 remains.
- The results are still only given as graphs of raw numbers, and my previous comments remain that we cannot know if they are meaningful without proper statistical analysis taking into account intra-group variability. This is especially highlighted in the fact that the multilingual group outperform the control group in two of the four competences, and overall, already in the youngest group, which are now shown to be the same age as the onset of the third language; either, then, the benefits of multilingualism must be almost instantaneous (not likely), or this group just happened to already perform slightly better than the control group for any number of reasons. The same might be the case for all other group differences.  The authors do not respond to my overall recommendation for inferential statistics in their response. In response to my comment on a specific graph in the manuscript, they acknowledge that such small numbers must be interpreted with caution, but their revision in the manuscript in this regard is to present a possible explanation *if* the result is in fact meaningful; this does not establish the difference as real and thus ends up being pure speculation. I do not find the results meaningful in their current form.

In short, the only conclusion I can draw from this study is that being immersed in two versus one additional language in school has no obvious effect on overall development in the native language - but this seems trivial, as I see no reason to expect that it would, and *if* there are in fact subtle effects, the lack of proper data analysis means we cannot see them.

Author Response

Dear Reviewer, 

I appreciate the time and attention you has devoted to evaluating my manuscript.

However, I respectfully disagree with several points raised in the report, as I believe they do not accurately reflect an understanding of the object, objectives, and methodology of our study. 

Below, I respond point by point to the comments:

Absence of a clear research gap
The reviewer states that the theoretical framework "establishes that trilingual acquisition is not detrimental" and that, therefore, "it is not clear what the research gap is." However, our study does not aim to assess whether trilingualism is harmful, but rather to examine to what extent exposure to a third language influences L1 oral competence in early stages. The reviewed literature acknowledges that exposure is a key factor, but there are few empirical and comparative studies that analyze how L3 acquisition contexts may manifest in L1 competence, particularly in institutional educational settings. Our contribution precisely addresses this gap

Criticism regarding the lack of expected effects in Spanish
The reviewer states that Spanish exposure is equivalent in both groups and that no differences should be expected. Precisely, our study takes that equivalence as a starting point to examine whether subtle differences in L1 oral production may still emerge due to the multilingual context. This type of experimental design (controlled in terms of exposure to the language under investigation) allows for better isolation of possible effects of the multilingual environment. At no point do we claim that L3 acquisition negatively affects L1 development; rather, we explore whether contextual differences are reflected in linguistic performance.

Transfer/CLI and its relevance to the study
Although the study does not focus strictly on interlinguistic transfer phenomena, the review of CLI is justified within the general framework of L3 acquisition in children, and it helps contextualize how simultaneous language learning may influence linguistic representations and production patterns. Since the study’s object is oral L1 production in a multilingual setting, this background is relevant to understanding interactional linguistic dynamics in school contexts.

On hypotheses and research questions
The reviewer indicates that no results are presented regarding the benefits of knowing an L2 for learning an L3. However, this is not the study's focus. The research questions focus on L1 competence in a trilingual context, not on L2-to-L3 transfer. The hypotheses and analyses are aligned with this scope. We believe there is a misunderstanding of the study’s objectives and design.

On the reduced number of participants with French as L2
This point was raised in the previous version and was addressed with the available data. Nevertheless, we reiterate that the study group is representative of the real educational context where L3 is taught, and that L2 heterogeneity is acknowledged as a limitation in the conclusions. This variation does not invalidate the study but reflects the sociolinguistic reality of the analyzed environment.

On statistical analysis
The reviewer insists on the lack of inferential statistics. While we acknowledge that the study could be enriched with more robust analysis, the qualitative and descriptive methodology was intentionally chosen due to the exploratory nature of the research. The total sample and its distribution by age prevent the reliable application of certain parametric tests. Nonetheless, sufficient data is provided to identify trends that justify future longitudinal and quantitative studies. This approach does not invalidate the research, but rather positions it within its rightful scope: exploratory and descriptive.

On the supposed triviality of the finding
Finally, the reviewer claims that the main finding —that there is no negative effect on L1 in trilingual contexts— is trivial. We strongly disagree. In contexts where early trilingualism is still perceived as a possible source of interference or overload, empirically demonstrating that L1 is not affected is relevant both scientifically and pedagogically.

Conclusion
I believe your observations do not accurately reflect the theoretical framework, methodological design, or the objectives of our study. In several instances, there are misinterpretations or expectations that fall outside the scope of an exploratory study. 

Sincerely

Reviewer 2 Report

Comments and Suggestions for Authors

Third Languages Acquisition (TLA): educational multilingualism at early ages

This study deals with the acquisition of L3 by comparing it to the acquisition of L2 to see to what extend simultaneous learning of three languages can benefit or obstruct a typical/normal language development of the L1 and it is based on the results provided from the Navarre Oral Language Test-revised.  

 

The authors have addressed most of the aspects that were previously indicated (i.e., more updates references, the reorganization of the theoretical background, clearer discussion), and this has resulted in a more coherent and up to date manuscript. However, there are some issues that are claimed as solved, yet, they are not.

These issues are listed below:

• The term mother tongue is obsolete, yet the authors have decided to maintain it and not address this issue which was raised in the previous review. In any case, if an acronym is provided, then it should be used. The first time reference is made to the mother tongue (MT/L1) is in line 36 and the full form with its acronym is provided once again in line 45. And later reference is made to primary language (MT/L1) (line 281) Please, check elsewhere and unify.
•  
• Figures should be on the same scale. Comment 5 in the cover letter states:

Comment 5: The figures provided should include axes (scales) that are unified. And these scores should also include percentages. The figures are very confusing and there is no consistency in the scales.

Response: We fully agree with the reviewer that the figures in the original version lacked consistency and clarity. All figures have now been revised: axes have been unified, percentage values have been included, and a consistent scale has been applied across all graphs. These visual improvements are intended to facilitate comparison across groups and age levels and to enhance the overall readability of the results section.

However, there is no difference between the figures in the original version and the reviewed version.

• No significant improvements in the results section are appreciated. Please, clarify.
• Selinker´s interlanguage theory (1969), if it is included in the discussion, it needs to be incorporated in the theoretical background. The same goes for the McLaughlin’s restructuring hypothesis (1984).
• The authors claim that they have included references to Meisel 2009 and the critical period, but this reference has not been included. Please, clarify.
•  

Please, find below issues that are found in the new improved manuscript:

• Line 48: a comma is missing after et al. Please, check elsewhere and unify. Also, when three or more authors are part of a study, et al. should be used. Please, unify.
• Line 60: “cross-linguistic CLI” cross-linguistic should be deleted since CL stands for cross-linguistic
• Line 147: Diouf (2008) viewS multilingualism
• Lines 201-206: This paragraph is unclear. Which are the three main objectives exactly? Numbering these could facilitate the reading.
• The use of third language acquisition and L3 acquisition should be unified (for example line 233 versos 109 where third language acquisition (TLA) is used and then yet again the full form with the acronym is provided in line 253. Please, check elsewhere. The same stands for the use of L2 and L3.
• Line 297: If you are citing different work provided by the same author, these should be included in only one reference.
• Line 302: Which criteria is used to order the studies? Please decide whether you follow the alphabetical order or the year of publication and correct elsewhere.
• Line 312: transfer and CLI make reference to the same phenomenon. Please, unify.
• Lines 354-356: this sentence seems to be incomplete.
• Line 376: what does “deeper acquisition patterns” make reference to?
• Line 380: why is (MT/L1) included there?
• Line 402: “In line with this” does not seem very academic. Consider using “in a similar vein” or similar.
• Line 606: MT is repeated
• Line 609: the acronym OL has already been used. Please unify.
• Line 644: is the use of bold necessary?
• Lines 705-707: why are these listed one after the other in separate lines? Why are they not simple listen one after the other in lien 704.
• Lines 734 and 735 are partially covered by a figure.
• Line 744: In my opinion, figure 1 does not add the understanding of the results. What it represents would be much more comprehensible if it is written out. In any case, if you decide to keep the figure, be consistent with the format and incorporate the 78% in the pie chart.
• Lines 746-763: This information should be represented in a table which actually contains the information that is being referenced. Table 2, if included, needs to be described.
• Line 1004: instead of “mediums do instruction” use “means of instruction”.

Author Response

We confirm that all requested changes have been made and the manuscript now reflects these improvements throughout. We appreciate the reviewer’s detailed comments, which have helped us enhance the rigor, clarity, and consistency of the work.

Thank you again for your valuable feedback.

1. Mother tongue terminology and acronym consistency:

1. • All references to "mother tongue" have been reviewed and standardized. The acronym (MT/L1) is introduced at first mention and used consistently thereafter. The alternative term "primary language" has been replaced to maintain uniformity.
2. Figures and scales:
   • All figures have been thoroughly revised. Axes and scales have been unified (12,5 and 7)
3. Inclusion of Selinker (1969) and McLaughlin (1984) in theoretical background:
   • These references are now properly incorporated into the theoretical background section.
4. Meisel (2009) and the critical period hypothesis:
   • Upon review, we have not found this reference in the current version of the text. Therefore, no changes were necessary on this point.
5. Line 48 - Comma after "et al." and citation consistency:
   • Comma placement has been corrected and "et al." usage has been standardized for all citations with three or more authors.
6. Line 60 - "cross-linguistic CLI":
   • The redundant "cross-linguistic" before CLI has been removed.
7. Line 147 - Subject-verb agreement:
   • Corrected to "Diouf (2008) views multilingualism".
8. Lines 201–206 - Clarity of objectives paragraph:
   • The paragraph has been rewritten for clarity and the three main objectives are now clearly numbered.
9. TLA/L3 terminology consistency:
   • Terminology related to "third language acquisition" and "L3 acquisition" has been unified. The acronym TLA is introduced at first mention and used consistently throughout, as are L2 and L3.
10. Line 297 - Multiple works by the same author:
    • Multiple works by the same author have been consolidated under a single reference entry.
11. Line 312 - "transfer" and "CLI" consistency:
    • Terminology has been unified; we now consistently use "CLI".
12. Line 376 - Clarification of "deeper acquisition patterns":
    • A brief explanatory phrase has been added to clarify the meaning of "deeper acquisition patterns".
13. Line 380 - Redundant (MT/L1):
    • The redundant acronym has been removed.
14. Line 402 - Register improvement:
    • "In line with this" has been replaced with "In a similar vein" for more formal tone.
15. Line 606 - MT repetition:
    • The repetition has been corrected.
16. Line 609 - Acronym OL consistency:
    • The acronym "OL" has been reviewed and unified across the manuscript.
17. Line 644 - Bold formatting:
    • Unnecessary bold formatting has been removed.
18. Lines 705–707 - List formatting:
    • Items have been reformatted to improve readability and consistency.
19. Lines 734–735 - Figure overlap:
    • Formatting corrected so no text is obscured by figures.
20. Line 744 - Figure 1 clarity and relevance:
    • Figure 1 has been revised for clarity, the 78% value incorporated, and formatting standardized.
21. Lines 746–763 - Representation in table format:
    • The information has been reformatted into a properly labeled Table 2, which is now described in the main text.
22. Line 1004 - "Mediums of instruction":
    • Corrected to "means of instruction" as suggested.

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

These are some of the issues that you need to address. Some of these have already been indicated to you, however, they continue to be an issue.

 

Line 12: be careful with the angle brackets

Line 16: space missing after OL

Line 19: too much space between in and L1

Line 43: space missing between a and L3

Line 62: TLA is Third Language Acquisition, thus in “the acquisition of TLA” one of the acquisitions is redundant.

Line 87: “their edited volume” consider deleting. This information in redundant. Also, an edited volume cannot highlight, but something can be highlighted in the volume.

Line 122: too much space between affirmed and in.

Line 138: please review the spacing

Lines 151-152: This sentence is unclear. Please, clarify.

Line 184: too much space at the beginning.

Line 251: why is the L1 now referred to as “primary language.” Please unify.

Line 252: space missing after OL

Line 262: which criteria are used to order the authors? There are inconsistencies here and elsewhere. Please revise. This has already been highlighted in previous reviews.

Line 267: “Cenoz (2000, 2001b,1997)” which criteria are used for the year of publication here? Please, correct elsewhere.

Line 272: which criteria are used to order the authors?

Line 311: there is no need to use and acronym if it is not going to be uses elsewhere. you provide the acronym DMM, but you do not use it elsewhere.

Line 319: now “first language” is used. Please unify the terminology.

Line 346: the footnote in unclear. Please, clarify.

Line 542: use past tense with the verb “pass”  

Line 547: space missing between “OL” and “in”

Lines 548-555: are repetition of what was just said in the paragraph above and thus should be deleted or lines 541-555 should be rephrased so that there is no repetition

Lines: 568: figure 1 should have a title and the title should not be what the colors represent.

Line 571: indicate the number of the table and not the title.

Lines 575-601: how is this information different from the information in table 2? It is unclear why the same scores are being repeated but just in another format. Keeping the table makes much more sense, since it represents the data in a more organized and visual fashion.

Lines 611-635: the interpretation of the results should not be written in point form. Please, rephrase into narrative.

Lines 686-689: Figure 2 has two titles. Please, delete the second one.

Line 695: change “as shown by the orange line versus the blue line in the figure 2” to “as shown in figure 2.”

Lines 706-707: Please, provide a title for figure 3 and delete the information regarding colors. Please, apply this to the rest of the figures. Also, it is essential that scales are added to the figures. In their current form, they are not clear and, most importantly, they are not comparable.

Lines 755-819: the discussion is written in point form in terms of analysis and interpretation. Consider rephrasing this into a simple narrative.

Line 851: change “dip” to “decrease”

Line 859: this information should not be included: “we have updated our theoretical references to more adequately reflect research on child multilingualism”. Please, delete and rephrase.

line 833: space missing between OL and development

Line 889: use only the acronym

line 893: opening bracket missing

lines 892-985: unclear. Please rephrase.

Line 907: space missing between “with” and “L1”

Lines 1037-1038: some abbreviations are not included in the list. Please, review and include the ones that you have finally decided to include and delete the ones that are not relevant.

 

Some of the aspects from the cover letter and comments that need clarification:

 

YOU CLAIM: Mother tongue terminology and acronym consistency: All references to "mother tongue" have been reviewed and standardized. The acronym (MT/L1) is introduced at first mention and used consistently thereafter. The alternative term "primary language" has been replaced to maintain uniformity.

YET: for example, in Line 35: the term “mother tongue” appears. It is obsolete. There has been a great change in our society and we, as researchers, should keep up with the terminology. Please, change “mother tongue” to “first language” (L1). The term “first language” is also consistent with the acronym. This has already been highlighted in previous reviews.

ALSO: Line 31: the use of the term “mother tongue” is somewhat obsolete nowadays. Consider rephrasing to L1 (first or native language) and correct it elsewhere.

Response: (NOT PROVIDED)

Line 31: MT/L1 is the same thing. Consider deleting MT, since this term is obsolete. Also, what exactly is the difference between the L1 and MT/L1?

Response: (NOT PROVIDED)

 

YOU CLAIM: Figures and scales: All figures have been thoroughly revised. Axes and scales have been unified (12,5 and 7)

YET: There is a difference between figures 2 and 3 when compared to 4 and 5. And all these are different from figure 6 and 8. And where is figure 7?

 

YOU CLAIM:  Line 48 - Comma after "et al." and citation consistency:

Comma placement has been corrected and "et al." usage has been standardized for all citations with three or more authors.

YET: Line 279: “Cabrelli, Puig-Mayenco, & Rothman, 2023” should be “Cabrelli et al.”Line 280: “Llop Naya, Puig-Mayenco, and Paradís (2024)” should also be et al. here as well. And please use “et al.” where adequate throughout the manuscript.

 

YOU CLAIM: Line 312 - "transfer" and "CLI" consistency: Terminology has been unified; we now consistently use "CLI".

YET: Lines 45- 61: CLT appears for “transfer”. What is the difference between CLT and CLI? You claim to have unified the use of terminology, but this is not the case regarding crosslinguistic influence.

 

YOU CLAIM: Comment (Line 521): “Exhibits superiority” sounds odd and should be rephrased. Response: The term has been replaced with “performs at a higher level,” which better aligns with scientific and neutral terminology.

YET: Line 744: the term “superiority” appears. It seems too harsh in this context. Please, rephrase here and elsewhere.

Author Response

I am writing to confirm that all the requested changes have been completed. I have also carried out a thorough revision of the entire article, including the bibliography, to ensure accuracy and consistency. I trust that the manuscript is now ready for publication, and I remain at your disposal for any further clarifications if needed. I sincerely appreciate the careful work carried out during the review process and look forward to your feedback.

Best regards,

Author Response File: Author Response.docx