# Children in French overseas departments are at a 3-fold increased risk of developing reading problems

Stéphanie Ducrot, Laurie Persia-Leibnitz, Marie Vernet, Brice Brossette, Chloé Prugnières, Jonathan Grainger

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Stéphanie Ducrot, Laurie Persia-Leibnitz, Marie Vernet, Brice Brossette, Chloé Prugnières, et al. Children in French overseas departments are at a 3-fold increased risk of developing reading problems. International Journal of Educational Development, 2025, 115, pp.103277. 10.1016/j.ijedudev.2025.103277. hal-05043884v2

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# Children in French overseas departments are at a 3-fold increased risk of developing reading problems

S. Ducrot<sup>a,b,e,*</sup>, L. Persia-Leibnitz<sup>a,c</sup>, M. Vernet<sup>a,d</sup>, B. Brossette<sup>a,e</sup>, C. Prugnières<sup>a</sup>, J. Grainger<sup>b,f</sup>

## ARTICLE INFO

### Keywords:

Screening tool

Visuo-attentional abilities

Reading deficit

Educational disparities

Minority populations

## ABSTRACT

France ranks among the countries where socio-economic and cultural inequalities critically impact educational trajectories. Here we report our findings from a study using the DEM-test for preliminary screening of at-risk school children in Martinique, a French overseas department. The present study aimed to (1) highlight the alarming situation in the French overseas departments regarding the number of children experiencing reading difficulties and (2) provide an effective tool for early detection of children at risk for low academic achievement. A standard DEM-test was administered to 399 school-aged children (6–11 years) in Martinique, alongside reading accuracy and fluency assessments using the Alouette test. Based on our recent norms established from a sizeable school-based cohort in mainland France, we identified nearly fifty percent of the children in Martinique screened as at risk for reading problems. This finding confirmed the critical need for large-scale implementation of early screening measures for at-risk children in these geographic areas during their initial years of formal education. We also demonstrated that the DEM test could be a valuable first-line tool across numerous countries and socio-cultural contexts. We believe our results may assist public education and health policies in addressing territorial and educational inequalities.

## 1. Introduction

France ranks among the countries where socio-economic and cultural inequalities critically impact educational trajectories (OECD, Pisa 2022). Geographical disparities, particularly between mainland France and its overseas departments, exacerbate these challenges. A recent government report (Giraudeau-Barthet, 2024) reveals that while 11.8 % of young people in mainland France (MF) struggle with reading, this proportion rises to 28 %-53 % in French Overseas Departments (FOD). The French Economic, Social, and Environmental Council (2024) has

mandated an urgent plan to address the educational needs of these overseas territories, underscoring the necessity for early screening of students facing challenges with basic reading skills.

Many factors could make the difference between a good and a poor reader in the reading process. One of these is related to visuo-attentional processing skills. Previous research has established a strong relationship between visual attention and reading ability in children (see Grainger et al., 2016, for a comprehensive review). Children with underdeveloped visual-attentional skills are at an increased risk of reading difficulties, although not all such children will necessarily struggle with

<footnote><sup>a</sup> Aix-Marseille Univ, CNRS, LPL, Aix-en-Provence 13100, France</footnote>

<footnote><sup>b</sup> Institute for Language, Communication, and the Brain, Aix-Marseille Université, Aix-en-Provence, France</footnote>

<footnote><sup>c</sup> Academy of Martinique, Les Hauts de Terreville, Schoelcher, France</footnote>

<footnote><sup>d</sup> Centre de jour enfants, Centre hospitalier de Digne-les-Bains, France</footnote>

<footnote><sup>e</sup> Aix-Marseille Univ, Pole Pilote AMPIRIC, Marseille 13013, France</footnote>

<footnote><sup>f</sup> Centre de Recherche en Psychologie et Neurosciences, CNRS & Aix-Marseille University, Marseille, France</footnote>

<footnote>* Correspondence to: Laboratoire Parole et Langage, CNRS & Aix-Marseille Université, 5 Avenue Pasteur, Aix-en-Provence 13100, France.</footnote>

<footnote>E-mail address: Stephanie.ducrot@univ-amu.fr (S. Ducrot).</footnote>
reading. Even though they may still learn to read, reading may require excessive cognitive effort. Depending on their severity, these visuo-attentional difficulties can lead to difficulty in tracking, orienting, and sustaining attention and focus, resulting in less efficient eye movement behavior and reading delays. We argue that systematically evaluating these skills could help identify reading problems at the onset and facilitate preliminary screening (Vernet et al., 2024).

Numerous studies mainly conducted in WEIRD (Western, educated, industrialized, rich, and democratic) countries demonstrate that the DEM-test<fnref n="1" /> is a reliable, quick, and user-friendly clinical tool that can be used for measuring visual attention efficiency and predicting reading difficulties (Facchin, 2021; see also Hopkins et al., 2019; Wood et al., 2018, for strong correlations between DEM parameters and academic performance, and Vernet et al., 2022, 2024, for screening purposes). A significant challenge remains to prevent the worsening of educational and territorial inequalities through rigorous and systematic screening of children at risk for reading difficulties (RD) in the FOD.

Here, we report the results of a study that used the DEM-test to first screen children from Grades 1–5 in several schools in Martinique (a French overseas department).

# 2. Method

## 2.1. Participants

A total of 399 children participated in the study, including 200 females and 199 males. Generally, all the participants had normal or corrected-to-normal vision. None of them suffered from any known neurological, psychiatric, or emotional disorders. The reading level was also assessed to identify children with and without RD (i.e., scores below −1 SD on at least one index of the Alouette test for the RD group and superior to −0.5 SD on the Alouette test for the noRD group). The inclusion criteria were the same as those described in the study by Bellocchi et al. (2021). Children were recruited from four schools in Martinique, and each child completed the DEM-test and the Alouette test in a single session. The study received approval from the French Ethics Committee Review Board (2023–01–05–04) and followed the guidelines in the Declaration of Helsinki (World Health Organization, 2008). Written informed consent was obtained from all participants and their legal guardians, with particular attention given to ensuring comprehension among families facing socio-economic or linguistic challenges. This included providing verbal explanations in French and Creole when necessary.

## 2.2. Material

### 2.2.1. DEM-test (Garzia et al., 1990)

The DEM-test consists of a pre-test to familiarize children with the digits, followed by three tests (A, B, and C) presented on separate sheets. Initially, the pre-test ensures that children are familiar with the digits they will encounter. In tests A and B, participants read two vertical columns of twenty digits aloud, aiming for speed and accuracy. Test C, a horizontal task, challenges children to read 80 digits arranged across

five irregularly spaced lines, simulating a realistic reading context. This test records both the naming times and any errors made, yielding three primary indices: (1) Vertical Time (VT): The total time in seconds for tests A and B combined; (2) Adjusted Horizontal Time (AHT): The time taken for test C, adjusted for errors such as additions or omissions; and (3) The total Number of Errors (ERR): The total errors made during test C, which includes addition, omission, substitution, and transposition errors.

### 2.2.2. Alouette test (Lefavrais, 2005)

The Alouette test is a widely recognized tool in France for assessing reading efficiency among children. In this assessment, participants had three minutes (180 seconds) to read a 265-word text aloud as fast and as accurately as possible. Currently, the test is standardized for assessing reading performance in children aged 5–14. The text consists of syntactically correct but semantically impoverished sentences (e.g., "Le printemps a mis ses nids"; "The spring has put its nests"), ensuring a focused evaluation of decoding skills. It includes very low-frequency words (e.g., "pampres") and irregular words (e.g., "nœud"), as well as orthographic traps such as silent letters (e.g., "nids" /ni/) and phonologically similar items (e.g., "Annie/amie"). Additionally, the text is presented in varied font sizes and is surrounded by illustrations designed to induce contextual errors. Three key measures were collected: M (Mots; total number of words correctly read), TL (Temps de Lecture; total reading time), and E (total number of reading errors). These measures were used to compute two key indices: Reading accuracy index (CM) = [(M – E)/M * 100] and Reading fluency index (CTL) = [(M – E)/TL * 180].

## 2.3. Procedure

Children from four Martinique Academy schools participated in the study, following the same procedure as Vernet et al. (2024). Each child was tested individually in a quiet, comfortable room at their school during regular hours. All children completed the DEM-test and the

<caption>Table 1</caption>

Characteristics, DEM-test, and Alouette-test performances of our sample in Martinique.

<table><thead><tr><th></th><th>CP</th><th>CE1</th><th>CE2</th><th>CM1</th><th>CM2</th></tr></thead><tbody><tr><td><strong>Demographics</strong></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>N</td><td>77</td><td>85</td><td>69</td><td>97</td><td>71</td></tr><tr><td>Age (SD)</td><td>79,47<br>(3,67)</td><td>90,37<br>(4,36)</td><td>101,28<br>(4,37)</td><td>113,27<br>(5,12)</td><td>126,23<br>(4,46)</td></tr><tr><td>Sex ratio (F/H)</td><td>46/31</td><td>29/56</td><td>41/28</td><td>(48/49)</td><td>35/36</td></tr><tr><td><strong>Maternal education level</strong></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Lower than high school</td><td>23</td><td>25</td><td>19</td><td>32</td><td>20</td></tr><tr><td>High school diploma</td><td>28</td><td>30</td><td>26</td><td>34</td><td>25</td></tr><tr><td>≥ 2-year university degree</td><td>26</td><td>30</td><td>24</td><td>31</td><td>26</td></tr><tr><td><strong>DEM-test</strong></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>VT(SD)</td><td>80,712<br>(27,1)</td><td>59,200<br>(14,3)</td><td>54,043<br>(13,7)</td><td>49,031<br>(8,7)</td><td>44,014<br>(9,4)</td></tr><tr><td>AHT (SD)</td><td>136,770<br>(48,9)</td><td>94,532<br>(37,2)</td><td>80,171<br>(30,9)</td><td>67,313<br>(21,4)</td><td>53,912<br>(12,2)</td></tr><tr><td>ERR (SD)</td><td>23,481<br>14,1</td><td>16,941<br>(12,8)</td><td>11,507<br>(12,1)</td><td>8,062<br>(9,0)</td><td>5,113<br>6,6</td></tr><tr><td><strong>Alouette test</strong></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>CM (SD)</td><td>64,1<br>(23,8)</td><td>81,193<br>(10,6)</td><td>86,384<br>(9,1)</td><td>88,329<br>(7,7)</td><td>90,928<br>(6,2)</td></tr><tr><td>CTL (SD)</td><td>51,718<br>(40,7)</td><td>118,554<br>(60,1)</td><td>157,187<br>(76,6)</td><td>185,832<br>(74,2)</td><td>242,895<br>(90,9)</td></tr></tbody></table>

Notes. VT: Vertical Time; AHT: adjusted Horizontal Time; ERR: Errors; CM: Reading accuracy; CTL: Reading speed.

<footnote n="1">¹ Since its introduction in 1987, the DEM test has been primarily used by optometrists to detect eye movement disorders. The task consists of naming digits (displayed horizontally and vertically) in a reading-like condition without using eye-tracking. According to Garzia et al. (1990), vertical time (VT) in the DEM test primarily reflects rapid automatized naming (RAN) efficiency, whereas horizontal time (AHT) captures both RAN speed and oculomotor control, particularly reading-related saccadic eye movements. The relevance of AHT stems from its ability to engage visuo-attentional processing and cognitive demands analogous to those involved in reading, including sequential left-to-right visual scanning, line returns, and saccade programming with variable amplitudes (Ayton et al., 2009; Facchin, 2021).</footnote>
Alouette test during a single session (Table 1).

## 2.4. Data analysis

Statistical analyses were performed using R and JASP software. Shapiro-Wilk normality tests indicated non-normal distributions for variables such as reading fluency, reading accuracy, and DEM scores, leading to the use of non-parametric tests with a significance threshold of $p = .05$. Welch's t-tests compared existing French norms on MF children with our current findings, using Cohen's d for effect sizes. For analyses not accounting for age or school level, Z-scores were utilized, with positive scores indicating better performance. Spearman's correlations investigated the link between DEM-test performance and reading levels. Note that the Z-scores for the Alouette indices (CM and CTL) were calculated using new norms based on the performances of 3913 children (Ducrot et al., 2025, in preparation). ROC curve analyses assessed the DEM-test's ability to differentiate children with RD from children without RD, providing the Area Under the Curve (AUC) as a measure of diagnostic validity (see Hajian-Tilaki, 2013, for details).

## 3. Results

We investigated the effect of grade and gender on performance using Kruskal-Wallis tests, as well as the effects of age and gender. The results revealed a significant developmental trend for all variables [Grade: VT (H(4) = 158.389, p < .001), AHT (H(4) = 209.321, p < .001), and ERR (H(4) = 122.968, p < .001); Age: VT (H(5) = 142.067, p < .001), AHT (H(5) = 189.903, p < .001), and ERR (H(5) = 117.119, p < .001)]. In contrast, no significant effect of gender was observed for any of the DEM-test variables ($p > .05$) (Fig. 1). Regarding our recent norms established on a larger school-based cohort from mainland France ($n = 1062$; reference blinded, 2024, submitted for publication), the prevalence of visual-attentional deficits in the DEM test for the present sample was 1 in 3 children (35.34 % of FOD children had at least one score below -1.5 SD, Table 2).<fnref n="2" /> This prevalence is 3 times higher than in the MF normative group (11.77 %). We observed significant differences in the proportion of children with deficits between MF and FOD samples ($p < .001$ for all indices), with a higher percentage of FOD children displaying deficits on DEM scores than their MF peers. We also found strong correlations between all the DEM-test parameters and Alouette test outcomes (see Table 3): the less fluent and accurate the reading, the slower the VT and HT, and the higher the error rate. This supports previously reported associations between the DEM and reading performance (Ayon et al., 2009; Wood et al., 2018; Vernet et al., 2024).

Data from the Alouette test mirrored results from the DEM-test, revealing a high prevalence of children with RD in our FOD sample. As illustrated in Table 4, 193 FOD children were identified as having RD (i.e., score less than or equal to -1 SD on at least one index of the Alouette test), while 115 were categorized as no RD (i.e., scores above -0.5 SD). Significant differences were noted across all indices of the DEM-test between children with and without RD; the former were slower and less accurate than the latter. In our preliminary large-scale screening effort, ROC curve analyses provided convincing evidence that the DEM-test reliably differentiates between children with and without reading difficulties in our FOD sample. These analyses, detailed in Fig. 2, demonstrate that two indices of the DEM-test confidently distinguish between RD and no RD children. The AUC³s for VT [AUC = .733 ± .016 ($p < .001$), 95 % CI [0.672 – 0.788]] and AHT [AUC = .777 ± .015 ($p < .001$), 95 % CI [0.718 – 0.829]] were good while that for ERR was average [AUC = .675 ± .016 ($p < .001$), 95 % CI [0.615 – 0.606]]. The lower AUC for the errors index suggests that this measure may be less reliable for distinguishing between children with and without reading difficulties. Future research could explore whether refining or combining the ERR index with other measures enhances diagnostic accuracy.

## 4. Discussion

We examined the performance of 399 school-aged children from Martinique, a French overseas department, using the DEM-test. Means, standard deviations, and percentile ranks for vertical time, horizontal time, and errors were established for FOD children between 6 and 11 years old<fnref n="4" />. Our findings reveal that eye movement and visuo-attentional difficulties—assessed through the DEM-test—are not only prevalent but are also up to three times more common in Martinique than in mainland France. Alongside the slower vertical and horizontal naming scores, FOD children exhibited six times more errors than their peers in MF (Bellocchi et al., 2021; Serdjukova et al., 2017). Regarding the nature of the errors made, 72 % of FOD children made omission errors (compared to 59 % of MF children), and 77 % of FOD children made addition errors (compared to 14 % of MF children). Moreover, our findings concerning the prevalence of both visuo-attentional and reading impairments in FOD children indicated a significant association between visual attention processing abilities and reading scores across all grades. This confirms the strong relationship between reading skills and visuo-attentional and saccadic eye-movement processes in FOD children. The DEM-test has also proven to be highly sensitive to children's reading difficulties, with Receiver Operating Characteristic (ROC) Area Under the Curve (AUC) values for AHT and VT, confirming its clinical utility and societal impact (.78 and.73, respectively). This allows for large-scale implementation in the French overseas departments for the early screening of at-risk children during their first years of formal education (Hopkins et al., 2019; Vernet, Bellocchi, et al., 2022; Vernet, Jover, et al., 2022). Early screening is particularly important in these geographic areas, enabling timely intervention in children's developmental trajectories. Tackling these challenges directly with effective tools like the DEM-test is essential for reducing the educational disparities children in the FOD face (Table 5).

Understanding the reasons behind the increased prevalence of at-risk children in the French Overseas Departments is not the primary focus of this paper. Nevertheless, we will address this topic briefly. To gain insights into the potential influence of environmental factors, we gathered additional data on crucial aspects related to the home literacy environment, such as leisure reading time, mother's education, and the number of books available at home). The correlation analyses between the indices of the DEM-test and the LRT showed a significant relationship for VT ($r = .19, p < .001$) and AHT ($r = .21, p < .001$). We obtained the same trends for the mother's diploma [VT: $r = .17, p = .002$; AHT: $r = .22, p < .001$] and number of books at home [VT: $r = .11, p = .04$; AHT: $r = .25, p < .001$; ERR: $r = .16, p = .004$] (see, Vernet et al., 2024 for similar results on the relationship between leisure reading time and DEM-test performance in MF children). The findings strongly support that home literacy practices are crucial in this context. Children from FOD are more likely to belong to disadvantaged backgrounds, to be underexposed to print, and to experience reading delays. Conversely, poor readers often avoid reading, which creates a detrimental cycle that hampers their capacity to automatize reading and develop accurate eye movements and visuo-attentional skills. It is

<footnote n="2">² As a reviewer rightly pointed out, it is important to note that the DEM test norms were established in mainland France, and cultural or linguistic differences in Martinique may have affected test performance</footnote>

<footnote n="3">³ AUCs > 0.9 are considered excellent, AUCs between 0.8 – 0.9 are very good, between 0.7 – 0.8 are good, 0.6 – 0.7 are average, and an AUC < 0.6 is poor (Choi, 1998)</footnote>

<footnote n="4">⁴ Note that we observed differences between the pre-existing French norms (reference blinded) collected from 1062 children in mainland France and the data from children in the French overseas departments presented in this paper, regardless of the DEM-test index (see Table 5).</footnote>
<figure><img src="image_3.png" /><figcaption>Fig. 1. Distribution of the FOD children's performances on the DEM-test indices according to school grades and age groups. Notes. VT: Vertical Time; AHT: adjusted Horizontal Time; ERR: Errors. FOD: French overseas department.</figcaption></figure>

<table><caption>**Table 2**

Prevalence of DEM-test deficits in Martinique and Mainland France children.</caption><thead><tr><th rowspan="2"></th><th colspan="4">FOD Children</th><th colspan="4">MF children</th></tr><tr><th>VT</th><th>AHT</th><th>ERR</th><th>At least 1 deviant index</th><th>VT</th><th>AHT</th><th>ERR</th><th>At least 1 deviant index</th></tr></thead><tbody><tr><th>N ≤ 1.5 ds</th><td>87</td><td>61</td><td>75</td><td>141</td><td>61</td><td>65</td><td>68</td><td>125</td></tr><tr><th>N</th><td>399</td><td>399</td><td>399</td><td>399</td><td>1062</td><td>1062</td><td>1062</td><td>1062</td></tr><tr><th>% ≤ 1.5 ds</th><td>21,80</td><td>15,29</td><td>18,80</td><td>35,34</td><td>5,74</td><td>6,12</td><td>6,40</td><td>11,77</td></tr></tbody></table>

Notes. VT: Vertical Time; AHT: adjusted Horizontal Time; ERR: Errors; CM: Reading accuracy; CTL: Reading speed; FOD: French overseas department; MF: Mainland France

<table><caption>**Table 3**

Correlation between the DEM-test indices and the reading performances assessed by the Alouette-test indices according to the FOD children's school grades.</caption><thead><tr><th rowspan="3"></th><th colspan="7">Reading performance</th><th colspan="7">CTL (Z-score)</th></tr><tr><th colspan="6">CM (Z-score)</th><th colspan="6">CTL (Z-score)</th></tr><tr><th>CP</th><th>CE1</th><th>CE2</th><th>CM1</th><th>CM2</th><th>All grades</th><th>CP</th><th>CE1</th><th>CE2</th><th>CM1</th><th>CM2</th><th>All grades</th></tr></thead><tbody><tr><th>VT (Z-score)</th><td>.407***</td><td>.052<sup>ns</sup></td><td>.479***</td><td>.382***</td><td>.339**</td><td>.343***</td><td>.491***</td><td>.411***</td><td>.537***</td><td>.502***</td><td>.614***</td><td>.523***</td></tr><tr><th>AHT (Z-score)</th><td>.443***</td><td>.157<sup>ns</sup></td><td>.457***</td><td>.387***</td><td>.394***</td><td>.368***</td><td>.520***</td><td>.473***</td><td>.645***</td><td>.494***</td><td>.706***</td><td>.569***</td></tr><tr><th>ERR (Z-score)</th><td>.177<sup>ns</sup></td><td>.105<sup>ns</sup></td><td>.283*</td><td>.142<sup>ns</sup></td><td>.441***</td><td>.230***</td><td>.195<sup>ns</sup></td><td>.209<sup>ns</sup></td><td>.305*</td><td>.206*</td><td>.385***</td><td>.280***</td></tr></tbody></table>

### Spearman's Correlations

* p < .05, ** p < .01, *** p < .001

Notes. Since the data does not follow a normal distribution, the analyses performed were Spearman correlations. Note also that the z-scores in the DEM-test were previously inverted, so a positive z-score reflected a good performance, either a short naming time or a reduced number of errors.

VT: Vertical Time; AHT: adjusted Horizontal Time; ERR: Errors; CM: Reading accuracy; CTL: Reading speed. FOD: French overseas department.
<table><caption>**Table 4**
DEM-test and reading performance between RD and noRD children in Martinique.</caption><thead><tr><th rowspan="2">Measures</th><th colspan="2">RD</th><th colspan="2">noRD</th><th rowspan="2">p</th><th rowspan="2">Effect size<br>(r<sub>h</sub>)</th></tr><tr><th>Mean</th><th>SD</th><th>Mean</th><th>SD</th></tr></thead><tbody><tr><td><em>N</em></td><td>193</td><td>-</td><td>115</td><td>-</td><td>-</td><td>-</td></tr><tr><td><em>Alouette test</em></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>CM (Z-score)</td><td>-2.494</td><td>1.805</td><td>0.129</td><td>0.370</td><td>&lt; .001</td><td>-0.958</td></tr><tr><td>CTL (Z-score)</td><td>-1.222</td><td>0.561</td><td>0.459</td><td>0.698</td><td>&lt; .001</td><td>-0.949</td></tr><tr><td><em>DEM-test</em></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>VT (Z-score)</td><td>-1.117</td><td>1.615</td><td>-0.043</td><td>1.247</td><td>&lt; .001</td><td>-0.466</td></tr><tr><td>AHT (Z-score)</td><td>-0.844</td><td>1.687</td><td>0.302</td><td>0.817</td><td>&lt; .001</td><td>-0.553</td></tr><tr><td>ERR (Z-score)</td><td>-0.860</td><td>1.441</td><td>-0.161</td><td>1.155</td><td>&lt; .001</td><td>-0.351</td></tr></tbody></table>

Notes. VT: Vertical Time; AHT: adjusted Horizontal Time; ERR: Errors; CM: Reading accuracy; CTL: Reading speed; RD: reading difficulties; noRD: without reading difficulties

important to highlight those parents from socio-economically advan-
taged backgrounds tend to engage in shared reading more frequently
than their disadvantaged counterparts because they are readers, have
more resources to buy books, and also read various documents on what
is beneficial for children (Barone et al., 2021).

Several limitations of this study should be acknowledged. The pri-
mary limitation concerns the generalizability of our findings. The DEM-
test norms were established in mainland France, and cultural and lin-
guistic differences in Martinique may have influenced test performance.
Future studies should validate these norms in diverse socio-cultural
contexts to ensure the tool’s reliability across populations. Addition-
ally, examining the impact of socio-economic status, cultural practices,
and linguistic factors—such as the use of Creole at home versus French
in school—could provide a more comprehensive understanding of the
underlying causes of the observed reading difficulties. These factors may
interact with visual-attentional deficits, potentially exacerbating
educational disparities. A second limitation is the cross-sectional nature
of this study, which prevents us from establishing causal relationships
between visual-attentional deficits and reading outcomes. To address
this, future longitudinal studies are recommended to assess the long-
term impact of early screening and intervention on students’ academic
trajectories.

<figure><img src="image_4.png" /><figcaption>**Fig. 2.** ROC curve analyses for each DEM-test index between RD and noRD children in Martinique. Notes. RD: Children with reading difficulties; noRD: Children without reading difficulties; VT: Vertical Time; AHT: adjusted Horizontal Time; ERR: Errors.</figcaption></figure>
<table><caption>**Table 5**
DEM-test performance by age group in Martinique and Mainland France.</caption><thead><tr><th rowspan="3"></th><th colspan="3">DEM-test data</th><th colspan="3">Mainland France</th><th colspan="2">Welch t-tests</th></tr><tr><th colspan="3">Martinique</th><th colspan="3">Mainland France</th><th rowspan="2">p-value</th><th rowspan="2">Cohens' d</th></tr><tr><th>N</th><th>Mean</th><th>SD</th><th>N</th><th>Mean</th><th>SD</th></tr></thead><tbody><tr><td><strong>VT</strong></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>6</td><td>65</td><td>79.49</td><td>28.11</td><td>144</td><td>65.01</td><td>15.71</td><td>p &lt; .001</td><td>d = .711</td></tr><tr><td>7</td><td>90</td><td>62.28</td><td>17.71</td><td>213</td><td>55.40</td><td>13.50</td><td>p &lt; .001</td><td>d = .463</td></tr><tr><td>8</td><td>82</td><td>54.76</td><td>14.19</td><td>216</td><td>48.33</td><td>8.25</td><td>p &lt; .001</td><td>d = .629</td></tr><tr><td>9</td><td>81</td><td>48.86</td><td>9.19</td><td>194</td><td>44.93</td><td>8.80</td><td>p &lt; .001</td><td>d = .441</td></tr><tr><td>10</td><td>73</td><td>44.59</td><td>9.85</td><td>234</td><td>41.43</td><td>7.03</td><td>p = .011</td><td>d = .435</td></tr><tr><td>11</td><td>8</td><td>47.75</td><td>7.25</td><td>56</td><td>39.98</td><td>6.25</td><td>p = .019</td><td>d = 1.220</td></tr><tr><td><strong>AHT</strong></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>6</td><td>65</td><td>138.08</td><td>52.28</td><td>140</td><td>119.47</td><td>40.48</td><td>p = .013</td><td>d = .418</td></tr><tr><td>7</td><td>90</td><td>97.77</td><td>36.89</td><td>213</td><td>90.75</td><td>29.20</td><td>p = .111</td><td>d = .222</td></tr><tr><td>8</td><td>82</td><td>80.41</td><td>30.47</td><td>216</td><td>70.91</td><td>19.58</td><td>p = .010</td><td>d = .412</td></tr><tr><td>9</td><td>81</td><td>67.21</td><td>22.39</td><td>194</td><td>62.85</td><td>22.90</td><td>p = .146</td><td>d = .192</td></tr><tr><td>10</td><td>73</td><td>56.89</td><td>21.24</td><td>234</td><td>53.25</td><td>10.96</td><td>p = .163</td><td>d = .259</td></tr><tr><td>11</td><td>8</td><td>61.28</td><td>11.20</td><td>56</td><td>52.07</td><td>12.99</td><td>p = .059</td><td>d = .720</td></tr><tr><td><strong>ERR</strong></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>6</td><td>65</td><td>22.57</td><td>13.33</td><td>140</td><td>15.83</td><td>11.27</td><td>p &lt; .001</td><td>d = .564</td></tr><tr><td>7</td><td>90</td><td>18.57</td><td>14.45</td><td>213</td><td>11.82</td><td>10.46</td><td>p &lt; .001</td><td>d = .573</td></tr><tr><td>8</td><td>82</td><td>11.29</td><td>11.02</td><td>216</td><td>6.36</td><td>7.34</td><td>p &lt; .001</td><td>d = .580</td></tr><tr><td>9</td><td>81</td><td>8.38</td><td>9.32</td><td>194</td><td>4.36</td><td>6.17</td><td>p &lt; .001</td><td>d = .555</td></tr><tr><td>10</td><td>73</td><td>5.19</td><td>7.45</td><td>234</td><td>2.88</td><td>4.97</td><td>p = .015</td><td>d = .409</td></tr><tr><td>11</td><td>8</td><td>8.13</td><td>6.75</td><td>56</td><td>3.14</td><td>4.68</td><td>p = .078</td><td>d = 1.005</td></tr></tbody></table>

Notes. VT: Vertical Time; AHT: adjusted Horizontal Time; ERR: Errors

In summary, irrespective of the factors contributing to the high prevalence of reading difficulties among FOD children, early screening remains essential. We strongly advocate using the DEM-test as a primary screening tool to identify children at risk for reading difficulties and poor academic performance. The significant advantage of this screening test is its applicability across numerous countries. Indeed, while this research focuses on educational and territorial inequalities in the overseas departments, these disparities are present across various minority populations, where the socioeconomic situation is challenging, and the language of instruction often differs from the language spoken at home (as is the case in overseas departments). This proactive approach is more economical and beneficial than later intervention and treatment. To effectively address educational disparities, policymakers should consider integrating the DEM-test into routine school health screenings in French overseas departments as early as possible. Training programs for teachers and healthcare providers could further support the early identification and intervention of at-risk children.

### Informed consent statement

Informed consent was obtained from each participant and their legal tutors.

### Ethics statement

The study was conducted following the Declaration of Helsinki and approved by the ethics committee of Comité de Protection des Personnes from Aix-Marseille University (No. 2023-01-05-04) on 10 January 2023.

### Permission to reproduce material from other sources

All Tables and Figures have no copyright issue.

### Educational relevance statement

This article addresses educational and territorial inequalities in overseas departments. Our findings indicate that children in French Overseas Departments are three times more likely to develop reading difficulties compared to their mainland counterparts. Early screening is

particularly crucial in these geographic areas, as it enables timely intervention in children's developmental trajectories, thereby reducing the educational disparities they face. The screening test we used, a digit naming task, could serve as a valuable first-line tool across numerous countries. Indeed, these disparities are present among various minority populations, where socioeconomic conditions are challenging, and the language of instruction often differs from the language spoken at home.

### Funding

This research was partly supported by a grant from the Pilot Center for Research in Education Ampiric (EXPOLECT) to the first author and funding from the Carnot Cognition Institute to the first and last authors (EXPOLECT).

### CRediT authorship contribution statement

Conceptualization, S.D. and J.G.; methodology, S.D.; formal analysis, S.D. and M.V.; investigation, L.P. and C.P.; data curation, S.D. and M.V.; writing—original draft preparation, S.D.; writing—review and editing, S.D., B.B, M.V. and J.G.; supervision, S.D. and B.B.; project administration, S.D.; funding, S.D. and J.G.

### Declaration of Competing Interest

The authors declare no conflict of interest. The funders had no role in the design of this study, in the collection, analysis, or interpretation of the data, in the writing of the manuscript, or in the decision to publish the results.

### Acknowledgements

The authors would like to express their sincere gratitude to Madame Nathalie Mons, Rector of the Academy of Martinique, Academic Director of French National Education Services, and Chancellor of the University, for her support and for authorizing the conduct of this research. We also extend our thanks to the participating schools, teachers, parents, and children for their interest and engagement in this study.
# Data Availability Statement

The data presented in this study are available on request from the corresponding author due to confidentiality and privacy disclosure of the participants' identities and authorized sharing of the data.

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