Effect of precursors to the development of phonological awareness on early reading learning

Abstract

It is known, as a result of studies conducted in recent years, that phonological awareness is the best predictor of early reading ability and that deficiencies in its mastery are a clear indicator of possible reading difficulties. However, despite the importance of this skill, there are no studies focused on understanding how its development can be enhanced to promote reading learning and, in turn, contribute to the prevention of reading difficulties. The objective of this study was to determine which variables facilitate the acquisition of phonological awareness from the earliest stages of written language learning. A quasi-experimental design comparing groups with pretest and posttest measures was used. The study included 412 students who were between 5 and 6 years old at the time the program was implemented. The results indicate the existence of a series of skills that enhance phonological awareness and positively impact initial reading learning, such as vocabulary richness, auditory memory, verbal comprehension, processing speed, and visual memory.

Resumen

Se sabe como consecuencia de los estudios realizados en los últimos años que la conciencia fonológica es el mejor predictor de la capacidad lectora temprana y que carencias en su dominio es un claro indicador de posibles dificultades lectoras. Sin embargo, a pesar de la importancia que presenta esta habilidad no se encuentran estudios centrados en conocer cómo se puede potenciar su desarrollo con el propósito de favorecer el aprendizaje lector y a su vez contribuir a la prevención de dificultades lectoras. El objetivo de este estudio se ha centrado en determinar qué variables facilitan la adquisición de la conciencia fonológica desde las primeras fases en las que se accede al aprendizaje del lenguaje escrito. Se ha utilizado un diseño cuasi-experimental de comparación entre grupos con medidas pretest y postest. La muestra ha estado formada por alumnado de entre 5 y 6 años, en concreto 412 escolares han participado en el estudio. Los resultados señalan la existencia de una serie de habilidades potenciadoras de la conciencia fonológica y que impactan de manera positiva en el aprendizaje inicial de la lectura como es el caso de la riqueza léxica, memoria auditiva, comprensión verbal, velocidad de procesamiento y la memoria visual.

Introduction

Scientific interest in the cognitive precursors of early reading has increased in recent years because it constitutes an essential component of learning in the early years of schooling and is key to academic success at all educational stages (Ziegler & Goswami, 2005). Far from being a natural skill, reading is a cultural construct that requires explicit training in specific skills, including phonological awareness (Castles et al., 2018; Ehri, 2020). This is conceived as the ability to identify, segment, manipulate, and reflect on the sound units of speech, from words to phonemes (Gillon, 2018). This skill allows children to break down words into their constituent phonological parts and relate them with specific graphic units (graphemes), an essential process for learning the alphabetic principle. Consequently, phonological awareness acts as a bridge between oral language and access to written language.

The acquisition of accurate reading of the conversion from a natural, verbal, and transient communication system to a symbolic, visual, and permanent system. This transition does not occur automatically; rather, it requires the acquisition of specific metalinguistic skills that allow for explicit awareness of the sound structures of language. In this process, phonological awareness emerges not only as a key predictor of reading success but also as an active agent in the transformation of spoken language into written language (Castles et al., 2018; Ehri, 2020; Gutiérrez-Fresneda, 2025).

Numerous studies have shown that the development of phonological awareness is closely linked to reading learning trajectories. Longitudinal research has shown that learners with high levels of phonemic awareness tend to perform better in reading during the early years of school, regardless of other factors such as socioeconomic status or intelligence quotient (IQ), (Melby-Lervåg et al., 2020). It has also been shown that early stimulation of phonological awareness constitutes a key pedagogical strategy to prevent reading difficulties and optimize the development of written language, especially in transparent language contexts such as Spanish, where the grapheme-phoneme link is direct and consistent (Ziegler & Goswami, 2005). It has also been found that when these interventions are carried out systematically and sustained over time, they favor the acquisition of vocabulary, morphological awareness and the development of spelling skills (Melby-Lervåg et al., 2020). Its role is so relevant in the educational field that it has been observed that the benefits obtained in the preschool stage are maintained during the years of primary and even secondary education, reducing the gap between students with and without risk of presenting specific learning difficulties (Ehri, 2020).

The present study

The importance of phonological awareness has been demonstrated in all languages ​​(Lerner & Lonigan, 2016; Zugarramurdi et al., 2022), which places great value on this linguistic skill, although it has been found that not all students have the same level of mastery when they begin learning the written language (Piñas et al., 2020), even when they have been specifically trained through metaphonological skills programs (Navas-Ruíz & Duran-Llaro, 2024). In this sense, it has been found that deficiencies in certain cognitive functions are linked to difficulties in reading acquisition and also specifically with phonological awareness tasks (Abellán, 2022) because they involve simultaneous mental actions that select, inhibit or suppress information while requiring the main task to be kept in memory (Redick et al., 2007). Along with evidence indicating that certain cognitive actions directly influence the development of phonological awareness, there is no work focused on analyzing how certain linguistic and cognitive skills, essential in the early stages of learning, can contribute to improving the performance of this metaphonological skill, given its relevance in children's literacy development. To this end, this study aims to offer insights that will help identify how access to the literacy process can be improved. The research questions posed are as follows: (1) Will the group receiving specific instruction to develop lexical richness, auditory memory, verbal comprehension, processing speed, and visual memory achieve a higher level of phonological awareness development? (2) Will students who have received skills training before developing phonological awareness achieve better alphabetic knowledge acquisition?; and (3) Are the gains in phonological awareness development maintained one year later and do they support the decoding process in the early stages of reading?

Based on these issues, the following objectives are proposed: (1) To analyze the existence of a series of skills that positively impact the development of phonological awareness; (2) To identify whether improvements achieved in phonological awareness as a result of prior stimulation in a series of linguistic and cognitive skills contribute to better learning of the linguistic code, and (3) To determine whether the improvements achieved in access to the literacy process are maintained over time and contribute to improvements in subsequent reading development.

To this end, the degree of phonological awareness performance and its impact on the reading process are compared in two groups: one that has been previously trained to stimulate a series of linguistic and cognitive skills such as lexical richness, auditory memory, verbal comprehension, processing speed, and visual memory; and the other that does not receive this intervention. The hypotheses proposed are as follows: (1) Students who receive specific instruction to develop lexical richness, auditory memory, verbal comprehension, processing speed, and visual memory will achieve greater mastery of phonological awareness; (2) Students who benefit from the intervention program will more easily acquire the learning of grapheme-phoneme correspondence processes; and (3) The improvements in the development of phonological awareness acquired through the specific intervention are maintained one year later and significantly facilitate the access and development of reading learning.

Method

Participants

The study involved 412 schoolchildren aged 5 and 6 who were in their third year of early childhood education at the start of the study. The sample was randomly selected from different schools located in areas with a medium sociocultural level. The student selection criteria were: Spanish speaking, age appropriate for their educational level, and no physical, mental, or sensory impairments. The students were divided into two groups, those that would form part of the experimental group (those that would receive the intervention program) composed of 208 students (who at the start of the study were M = 5 years and 6 months old, SD = 0.45), of which 48.4% were boys and 51.2% were girls; and those that would form part of the control group, 204 students (who at the start of the study were M = 5 years and 5 months old, SD = 0.27), 47.6% were boys and 52.4% were girls. The contingency analyses carried out relative to the condition and gender did not show significant differences in the participants (X² = .56, p > .05).

Instruments

In order to measure the variables under study, the following assessment instruments were used, all of them with psychometric guarantees of reliability and validity.

Early Childhood Learning Assessment Test (PEAI) (Gutiérrez-Fresneda, 2019a)

To assess skills related to expressive richness, verbal comprehension, phonological awareness, and auditory memory, the Early Childhood Learning Assessment Test (3–6 years) was used. The score on each of these tests was obtained by assigning two points to each correct answer. These subtests have a Cronbach's alpha coefficient of .85. Composite reliability (CR) and average variance extracted (AVE) were calculated using the data from the present study. The results showed that reliability was high (CR = .93), and the average variance extracted was greater than .50 (AVE = 57.41%), reflecting that a substantial percentage of the variance is explained by the construct.

Visual Memory Assessment

To assess the level of development of visual memory, an ad-hoc test was developed, consisting of two tasks of progressively increasing complexity, each with five items. In the first, three images were presented, each of which disappeared after fifteen seconds. The three previous images were then shown alongside a new one, with the aim of identifying the new image. In the second task, four images were presented, followed by four images after fifteen seconds, of which only one had been seen before. The aim was to identify the image that had been presented initially. One point was awarded for each correct answer. The reliability of the test, carried out on the sample of participants and estimated using Cronbach's alpha, was 0.87. In addition, the composite reliability (CR) and the average variance extracted (AVE) were calculated with the data from the present study. The results showed that reliability was high (CR = .92), and the average variance extracted was greater than .50 (AVE = 58.42%), reflecting that a substantial percentage of the variance is explained by the construct.

Processing speed

To measure processing speed, the Rapid Automated Naming test (RAN; Wolf & Denckla, 2003), adapted to Spanish by Fonseca et al. (2019), was used. This test involves naming a total of 200 stimuli as quickly as possible. The stimuli were classified into four categories: digits, letters, colors, and drawings. The RAN task record records the time taken to name the stimuli along with the number of errors made. These two data points were used to generate an efficiency index based on the procedure used by Compton (2003), which involves converting scores into digits per second, letters per second, colors per second, and drawings per second. This test has a Cronbach's reliability coefficient of .80. In addition, composite reliability (CR) and average variance extracted (AVE) were calculated using the data from the present study. The results showed that reliability was high (CR = .93), and the average variance extracted was greater than .50 (AVE = 56.23%), reflecting that a substantial percentage of the variance is explained by the construct.

Evaluation of reading processes

To assess reading skills, four tasks from the Prolec-R test (Cuetos et al., 2007) were used: the letter name/sound tests, equality/difference, word reading, and pseudowords were used to assess lexical processes. The total score for each of these four tests was obtained by assigning one point to each correct answer. The reliability of the test administered to the study sample, estimated using Cronbach's alpha, was .93. In addition, composite reliability (CR) and average variance extracted (AVE) were calculated using the data from the present study. The results showed high reliability (CR = .91), and the average variance extracted was greater than .50 (AVE = 58.34%), reflecting that a substantial percentage of the variance is explained by the construct.

Design and procedure

The study used a quasi-experimental design with repeated measures at different times (pretest-posttest) and two groups (control and experimental). Before and after the implementation of the intervention program, data were collected on the various variables to be analyzed using the assessment instruments indicated in the previous section. One year after the intervention ended, a follow-up assessment was conducted using the same instruments. In all cases, the tests were administered by experienced and previously trained teachers to ensure consistency in the collection of results. Once the initial assessment was completed, the experimental group implemented the work program. It consisted of 48 sessions spread over 16 weeks (three sessions per week, each lasting 45 minutes). Once the intervention program was completed, all students received instruction in developing phonological awareness and acquiring alphabetic knowledge for 20 weeks. At the end of this period, both the control and experimental groups were assessed using the same instruments used in the initial assessment. The study had prior ethical approval from the university and adhered to the ethical values ​​required for research involving human subjects, such as informed consent, the right to all information about the study, data protection, confidentiality, freedom from discrimination, freedom from financial costs, and the freedom to withdraw from the program at any time.

Intervention program

Throughout the period in which the intervention program focused on specific training in the skills of lexical enrichment, auditory memory, verbal comprehension, processing speed, and visual memory was applied to the experimental group, the students in the control group followed the curriculum established in the official regulations. This program consisted of 48 sessions, each lasting forty-five minutes (Chart 1).

Chart 1.

Intervention program applied to the experimental group prior to phonological awareness instruction and written code instruction.

1st and 2nd week	3rd and 4th week	5th and 6th week	7th and 8th week
Auditory association through the recognition of non-linguistic sound elements presented in isolation to relate them to known elements.	Auditory discrimination through the differentiation of auditorily similar elements, either due to their similarity in sound or their relationship to the point and/or mode of articulation.	Auditory repetition through the recognition of sound elements presented both independently and in sequence to repeat them after listening to them.	Auditory recognition through the isolated recognition of linguistic elements to recall them after a short period of time.
Verbal association establishing relationships through experiences and learning in both formal and informal settings.	Identification of basic concepts in the everyday environment, allowing for the integration of information appropriately and accurately.	Identifying intruders by recognizing the elements that do not correspond to a specific category, exercising conceptual similarities and analogies.	Verbal comparisons establishing links of similarities taking into account their affinity and semantic characteristics.
Recognition and recall of actions for constructing sentences by previewing a series of images of the immediate environment.	Visual discrimination for the delayed recognition of a series of figures with a certain similarity in relation to shape and spatial position.	Verbal fluency by quickly naming a series of known elements.	Visual selection through rapid recognition of a series of elements that correspond to the given instruction.

9th and 10th week	11th and 12th week	13th and 14th week	15th and 16th week
Auditory integration, promoting the development of mental word representation through working memory retrieval.	Visual integration through the identification of objects that are missing certain elements.	Maze games that require agility to follow the correct path from the starting point to the end point, regulating speed and efficiency.	Visual association by replacing, associating and relating a series of symbols and objects with arrows based on their perceptual similarities.
Integration of information by performing actions with a certain agility based on visual stimuli, paying attention to codes or reference models.	Perception of differences by identifying models similar to a given one at a visual level with a certain degree of agility.	Figure-Ground recognizing a series of intertwined and hidden elements in an image.	Naming speed by quickly and accurately evoking a set of known stimuli.
Auditory association through the recognition of linguistic elements presented in a sequential manner to relate them to known elements.	Verbal evocation of known objects related to certain semantic fields through context-absent situations.	Visual discrimination by searching for elements identical to other dice, all with a high degree of visual resemblance.	Integration of information with a certain agility from visual stimuli, paying attention to reference codes or models.
Verbal fluency with agility based on the presentation of a series of given instructions.	Perception of differences by identifying similarities and distinctions based on color, position, and size, as well as the characteristics of different objects.	Auditory recognition through the recognition of various linguistic elements to recall them after a short period of time.	Expression of personal experiences through the visual presentation of a series of family events and occurrences.

Once the intervention program had been completed, all students, including those in the control and experimental groups, received instruction over a period of 24 weeks on the development of phonological awareness and language code learning with the aim of facilitating access to the literacy process.

Phonological awareness was worked on through different playful tasks involving activities such as identification, comparison, classification, substitution, and omission of syllables and phonemes, following a sequence and timing similar to that presented in the Advanced materials (Gutiérrez et al., 2015). Alphabetical knowledge focused on teaching the names of letters using mixed phonetic-based methods. The different spellings were presented together with words from the immediate environment, which were worked on at a visual, auditory, tactile, and articulatory level in a contextualized manner alongside their own names, as well as through posters, signs, recipes, and titles of children's stories, which were read collectively using the dialogic reading technique, characterized by simultaneous reading aloud by the teacher with interactive situations such as dialogue and question-asking. These two programs were carried out using the same materials and following the same teaching methodology.

Data analysis

In order to analyze the effect of the intervention program, descriptive analyses, mean (M) and standard deviation (SD) were first performed together with analysis of variance tests (ANOVA) on the pretest scores of each instrument, in order to verify the initial equivalence between the experimental and control groups. Subsequently, to determine whether the changes observed after the intervention differed significantly between the two groups, a multivariate analysis of covariance (MANCOVA) was applied, followed by individual analysis of covariance (ANCOVA) on post-test scores, incorporating the baseline values as covariates in order to control for their possible influence. Finally, the magnitude of the effect of the program was estimated by calculating Cohen's d, interpreted as small (d < 0.50), moderate (0.50 ≤ d < 0.80) or large (d ≥ 0.80). All statistical procedures were performed using the SPSS statistical package, version 22.0.

Results

Once the data were collected, and in order to analyze changes in the study variables, various descriptive analyses (means and standard deviations) were initially performed according to the different phases of the study (pretest, posttest, and differences before and after the intervention). Studies of variance were also performed on the pretest values, as well as analyses of covariance (MANOVAs, ANOVAs, MANCOVAs, and ANCOVAs) based on the changes in the groups and in the measurements before and after the implementation of the work program. Normality and homoscedasticity of the sample were checked using the Kolmogorov-Smirnov and Levene tests. In addition, the effect size was obtained. The data obtained through the MANOVA before treatment for the set of variables reflects that at this time there were no significant differences between the two groups, experimental and control, F(1, 84) = 2.37, p > .05. However, the data resulting from the MANCOVA considering the posttest-pretest differences, from the pretest values ​​as covariates presented significant differences F(1, 84) = 3.49, p < .05. This situation indicates that the effects of the applied work program had a positive impact on the improvement of student learning. Furthermore, it is observed from these same analyses carried out a posteriori one year later that the effects achieved through the educational intervention are maintained over time, strengthening and increasing their effectiveness (Tables 1, 2).

Table 1.

Means and standard deviations in the variables analyzed in the study, in the experimental and control groups in the pretest phase and in the pretest-posttest and pretest-follow-up differences.

	Pretest				Pretest-Posttest				Pretest-Follow-up
	Experimental		Control		Experimental		Control		Experimental		Control
Variables	M	DT	M	DT	M	DT	M	DT	M	DT	M	DT
Enhanced Skills
Lexical richness	4.11	0.34	4.19	0.21	8.34	0.46	5.43	0.45	8.57	0.54	5.25	0.47
Auditory Memory	4.23	0.28	4.32	0.53	8.21	0.38	5.62	0.57	8.34	0.36	5.42	0.61
Verbal Comprehension	4.62	0.46	4.38	0.29	8.12	0.48	5.26	0.62	8.23	0.47	5.53	0.44
Processing Speed	7.23	0.37	7.06	0.63	18.32	0.62	9.62	0.38	19.46	0.51	9.78	0.56
Visual Memory	4.72	0.52	4.35	0.27	8.56	0.29	5.03	0.49	8.75	0.64	5.12	0.43
Phonological Awareness
Syllabic Awareness	4.78	0.34	4.32	0.43	8.59	0.27	6.02	0.31	8.89	0.47	6.67	0.52
Phonemic Awareness	4.16	0.59	4.27	0.62	8.36	0.46	6.35	0.42	8.75	0.39	6.52	0.48
Cognitive Processes of Reading
Knowledge Letters	6.14	0.37	7.03	0.47	14.28	0.28	9.11	0.23	18.37	0.37	11.36	0.57
Same-Different	8.23	0.48	7.12	0.52	17.39	0.24	11.36	0.48	19.23	0.21	13.82	0.62
Reading Words	5.27	0.49	5.34	0.61	23.62	0.32	12.42	0.63	34.18	0.45	24.59	0.43
Reading Pseudowords	4.81	0.52	5.02	0.34	18.43	0.51	10.16	0.39	28.21	0.39	20.26	0.48

Note. *p < .05. **p < .01. ***p < .001.

Table 2.

Results of the analysis of variance in the pretest phase, covariance between the pretest-posttest phases, pretest-follow-up covariance and effect size in the different study variables, in the experimental and control groups in the initial phase, in the differences between the pretest-posttest and pretest-follow-up phases.

	Pretest			Pretest-Posttest			Pretest-Follow-up
	F (1.84)	p	d	F (1.84)	p	d	F (1.84)	p	d
Enhanced Skills
Lexical richness	2.02	.327	0.08	4.12	.003	0.65	4.27	.000	0.87
Auditory memory	2.09	.283	0.06	4.04	.001	0.72	4.18	.000	0.80
Verbal comprehension	2.34	.194	0.10	4.01	.000	0.34	4.08	.001	0.66
Processing speed	4.26	.317	0.12	6.12	.002	0.48	6.26	.000	0.81
Visual memory	2.53	.194	0.14	4.12	.000	0.34	4.32	.000	0.57
Phonological Awareness
Syllabic Awareness	2.42	.416	0.10	4.51	.001	0.58	4.36	.000	0.64
Phonemic Awareness	2.25	.383	0.08	4.26	.000	0.83	4.59	.000	0.89
Cognitive processes of reading
Knowledge Letters	2.26	.467	0.09	5.02	.000	0.72	6.62	.000	0.87
Same-Different	4.27	.428	0.10	6.11	.000	0.65	7.62	.000	0.73
Reading Words	3.12	.462	0.12	7.46	.000	0.78	9.05	.000	0.84
Reading Pseudowords	2.34	.553	0.14	6.58	.000	0.63	8.42	.000	0.81

Note. *p < .05. **p < .01. ***p < .001.

Impact of linguistic-cognitive skills training on phonological awareness

Regarding the first research question, which examined whether prior training in linguistic and cognitive skills, vocabulary, auditory memory, verbal comprehension, processing speed, and visual memory favored the subsequent development of phonological awareness, the study's statistical results offer strong evidence in favor of this hypothesis. First, the multivariate analyses confirm that both groups started from a comparable position: the MANOVA performed in the pretest for the set of variables considered "learning enhancers" showed no significant differences between the experimental and control groups, F(1, 84) = 2.17, p > .05, indicating initial equivalence before the intervention. However, after the training period, differences clearly emerged. The posttest -pretest MANOVA showed significant changes. F(1, 84) = 3.49, p < .01, and these results were confirmed by statistically controlling for initial scores using MANCOVA, F(1, 84) = 4.12, p < .01. Similarly, the differences were maintained and even consolidated in the follow-up carried out one year later, both in the MANOVA, F(1, 84) = 2.07, p < .01, as in the MANCOVA, F(1, 84) = 2.63, p < .01. This pattern confirms that the intervention produced generalized improvements in the set of trained skills, and that these improvements were stable over time.

Detailed analysis of each skill reinforces this conclusion. In vocabulary richness, the experimental group showed significantly higher scores at the end of the program (M = 8.34) compared to the control group (M = 5.43), and these differences not only persisted but even increased one year later (M = 8.57, M = 5.25). Statistical tests support these results using ANCOVA at the post-test, F(1, 84) = 4.12, p < .05, and at the follow-up, F(1, 84) = 4.27, p < .05, with effect sizes progressing from moderate to large (d = 0.65, d = 0.87). A similar pattern is observed in auditory memory, the experimental group clearly outperformed the control group both at the post-test (M = 8.21, M = 5.62) and at the follow-up (M = 8.34, M = 5.42). The differences were highly significant, F(1, 84) = 4.04, p < .001, with a moderate effect size (d = 0.72) immediately after training, which increased to a high level at follow-up F(1, 84) = 4.18, p < .001, d = 0.80.

Consistent improvements were also recorded in verbal comprehension. In the post-test, the experimental group obtained higher scores (M = 8.12) compared to the control group (M = 5.26), a difference that persisted one year later (M = 8.23; M = 5.53). ANCOVA showed significant effects in both assessments F(1, 84) = 4.01 and 4.08, p < .001), with the effect size increasing from small (d = 0.34) to moderate (d = 0.66), suggesting a progressive strengthening of this skill. Processing speed showed one of the most notable improvements after the intervention; the experimental group obtained M = 18.32 compared to M = 9.62 for the control group, and one year later the differences increased even further (M = 19.46, M = 9.78). ANCOVA analyses confirmed highly significant effects F(1, 84) = 6.12 and 6.46, p < .001. .001, with effect sizes increasing from moderate (d = 0.48) to large (d = 0.81). Finally, in visual memory, the pattern was similarly favorable to the experimental group, with higher means both after the intervention (M = 8.56, M = 5.03) and at follow-up (M = 8.75, M = 5.12). The analyses showed significant differences F(1, 84) = 4.12 and 4.32, p < .01, with effect sizes increasing from small to moderate (d = 0.34, d = 0.57).

Taken together, these results confirm that the program produced broad, significant, and sustained improvements. In all the skills trained, the magnitude of the effects tends to increase over time, and the experimental group developed a significantly stronger linguistic and cognitive foundation than the control group. This early strengthening of key skills constitutes the foundation that, as subsequent analyses of the study show, facilitates and enhances the development of phonological awareness, the central objective of the first research question.

Transfer of phonological awareness to alphabetic knowledge

To answer the second question regarding the transfer of phonological awareness to alphabetic knowledge, the changes produced in the PROLEC-R tests, focused on knowledge of the linguistic code and the decoding process, were analyzed. First, the pretest MANOVA confirmed that the groups started from similar levels before the intervention, with no significant differences in the set of variables F(1, 84) = 2.37, p > .05. However, after the intervention, the differences emerged clearly; the posttest - pretest MANOVA showed significant changes F(1, 84) = 3.16, p < .01, results that were maintained when the initial scores were controlled for using MANCOVA, F(1, 84) = 3.27, p < .01. This same trend appeared in the annual follow-up, both in the MANOVA, F(1, 84) = 2.72, p < .01, as in the MANCOVA, F(1, 84) = 3.82, p < .01, which demonstrates a robust stability of the effect of prior training on reading performance.

In the letter knowledge variable, the experimental group obtained significantly higher scores at the end of the intervention (M = 14.28) compared to the control group (M = 9.11), differences that increased one year later (M = 18.37, M = 11.36). The analyses performed using ANCOVA They indicated significant effects in both the post-test F(1, 84) = 5.02, p < .01, as in the follow-up F(1, 84) = 6.62, p < .01, moving the effect size from moderate to high (d = 0.72, d = 0.87) showing a consolidation process.

A similar pattern was observed in the same-different test, where the experimental group obtained better results in the post-test (M = 17.39) compared to the control group (M = 11.36), differences that increased one year later (M = 19.23, M = 13.82). ANCOVA analyses showed significant differences in the post-test. F(1, 84) = 6.11, p < .001 and in the follow-up F(1, 84) = 7.62, p < .001, indicating moderate effects sustained over time (d = 0.65 d = 0.73), with a tendency to increase.

In word reading, one of the most direct indicators of early decoding development, the experimental group showed significantly superior performance after the intervention (M = 23.62) compared to the control group (M = 12.42). These differences widened one year later (M = 34.18, M = 24.59). ANCOVA analyses confirmed statistically significant effects at the post-test. F(1, 84) = 7.46, p < .001, with moderate effect sizes (d = 0.78), which increased to high values on follow-up F(1, 84) = 9.05, p < .001, d = 0.84.

Finally, in pseudoword reading, a key indicator of mastery of the alphabetic principle, the experimental group again outperformed the control group in the post-test (M = 18.43, M = 10.16), with the difference widening considerably at follow-up (M = 28.21, M = 20.26). The differences were significant both at post-test F(1, 84) = 6.58, p < .01 and follow-up F(1, 84) = 8.42, p < .01, showing an effect size that evolved from moderate to large (d = 0.63, d = 0.81).

Taken together, these results confirm that prior training facilitated the acquisition of alphabetic knowledge and accelerated the development of decoding skills. The overall trend across all analyses, maintenance and increase in effect sizes, shows that prior training generated a robust and progressive advantage, enabling the experimental group to more effectively tackle the formal learning of the written code.

Maintenance of effects and contribution to decoding in the medium term

The third question focused on analyzing the persistence of the effects of the prior training and its sustained impact on decoding one year later. Multivariate analyses showed that the advantage of the experimental group not only persisted but strengthened over time. The follow-up-pretest MANOVA revealed significant effects F(1, 84) = 2.72, p < .01, and the MANCOVA confirmed this pattern even when controlling for baseline scores F(1, 84) = 3.82, p < .01, indicating that the intervention produced lasting and generalizable changes in reading performance.

Univariate analysis of each of the PROLEC-R tests also demonstrated the stability and expansion of the achievements. In letter knowledge, the effect size increased from moderate (d = 0.72) in the post-test to high (d = 0.87) at follow-up. In the same-different test, the effect size increased from moderate (d = 0.65) to a moderate-to-high level (d = 0.73). In word reading, one of the variables most sensitive to the intervention, the effect size increased from 0.78 to 0.84, both statistically significant (p < .001). Similarly, in pseudoword reading, a key component for assessing mastery of grapheme-phoneme correspondences, the effect size also increased from moderate (d = 0.63) to high (d = 0.81), with significant differences in both phases F(1, 84) = 6.58 and 8.42, p < .01. These patterns not only reflect the persistence of the effect but also a progressive strengthening of reading skills in the experimental group.

The combination of these results suggests that prior training provided a solid foundation that allowed students to benefit more effectively from formal reading instruction. The fact that the differences do not decrease over time, but rather widen, indicates a process of cumulative growth, in which initial learning enhanced subsequent reading development.

Discussion

The purpose of this study was to analyze how a set of linguistic and cognitive skills (lexical richness, auditory memory, verbal comprehension, processing speed, and visual memory) influences the development of phonological awareness and, consequently, early reading acquisition. The results provide strong evidence for the precursor role these skills play in the early literacy process, confirming that their early strengthening produces significant, sustained, and transferable effects. Taken together, the findings show that stimulating linguistic and cognitive competencies in an integrated manner fosters a more efficient reading trajectory, consistent with theoretical approaches that highlight the bidirectional relationship between language, cognition, and metaphonological skills (Gutiérrez-Fresneda et al., 2024; Ziegler & Goswami, 2005).

Impact of linguistic-cognitive skills training on phonological awareness

Regarding the first objective, the hypothesis was whether prior intervention in linguistic and cognitive skills would significantly improve the development of phonological awareness. The results confirm this hypothesis: the experimental group showed remarkable progress in both syllabic and phonemic awareness, far surpassing the control group. This result is consistent with the literature that emphasizes the importance of vocabulary and lexical richness in the early stages of education (Cunia, 2025; Gutiérrez-Fresneda, 2019b), as well as with studies that highlight the relationship between verbal comprehension and the ability to analyze language (Montiel, 2024; Parra & Sagñay, 2024).

Progress in auditory memory, an essential skill for storing and manipulating sound sequences, also contributed to metaphonological development, in line with the findings of Carreteiro and Figueira (2017). Similarly, the increase in processing speed, a key executive function for efficient language use, aligns with the research highlighting its predictive role in language learning (Urrutia & Roa, 2020). Improvements in visual memory reinforce this linguistic-cognitive foundation, as it facilitates the representation and retrieval of verbal and graphic information.

All of this explains why the participants were able to perform essential cognitive operations for phonological tasks more effectively, such as discriminating, segmenting, manipulating, and retaining speech units. The results thus support the initial hypothesis that the intervention strengthened the linguistic and cognitive processes that directly underpin the development of phonological awareness, as proposed by models that integrate language and cognition as interdependent systems (Gutiérrez-Fresneda et al., 2024; Ziegler & Goswami, 2005). This contribution is of great importance, as it could be a key element in compensating for many of the language development deficiencies that schoolchildren exhibit from an early age, which has a significant impact on learning to read and write.

Transfer of phonological awareness to alphabetic knowledge

Regarding the second objective, the hypothesis proposed that greater phonological awareness would facilitate the acquisition of alphabetic knowledge, especially in grapheme-phoneme correspondence and decoding. The results confirmed this hypothesis, as the experimental group showed solid progress in letter knowledge, visual discrimination, word reading, and pseudoword reading.

These findings align with studies highlighting the existence of linguistic mediation between spoken language and access to the written code, where the conscious identification of phonological units facilitates the establishment of systematic relationships between phonemes and graphemes (Gutiérrez-Fresneda et al., 2021; Sun et al., 2022). This transfer is enhanced by the prior strengthening of cognitive skills stimulated during the intervention, which is consistent with the arguments that metalinguistic skills and cognitive functions maintain a reciprocal relationship that supports reading acquisition (Abellán, 2022; Gallego & Figueroa, 2020).

This study expands upon previous contributions by demonstrating that this transfer is not automatic, but rather depends on the support provided by skills such as auditory memory, processing speed, and visual memory (Gutiérrez, 2018; Sellés & Martínez, 2008). Consequently, the intervention not only strengthened phonological awareness, but also created the necessary cognitive conditions for this skill to effectively translate into mastery of the alphabetic system.

Maintenance of effects and contribution to decoding in the medium term

Finally, regarding the third objective, the hypothesis was that the benefits of the training would be maintained over time and would continue to influence decoding a year later. The results confirm this hypothesis, showing that the improvements were not only maintained but also increased in magnitude across several key skills.

Follow-up revealed higher and stable levels in vocabulary, auditory memory, verbal comprehension, processing speed, and visual memory. This maintenance is essential, as these skills function as cognitive-linguistic scaffolding that supports reading progress. In parallel, the experimental group maintained significant advantages in reading words and pseudowords, demonstrating a progressive consolidation of the alphabetic principle.

This cumulative pattern suggests that the intervention acted as a long-term catalyst, promoting more efficient reading trajectories. Thus, it is confirmed that early stimulation of linguistic and cognitive skills does not produce fleeting benefits, but rather generates lasting effects that continue to support decoding in later stages.

In practice, based on the results of this study and considering the impact that the development of metaphonological skills has on both reading acquisition and the emergence of reading difficulties, we suggest implementing teaching programs aimed at developing the skills addressed in this study, which have been shown to have a direct impact on improving phonological awareness and access to written language. This includes vocabulary richness, auditory memory, verbal comprehension, processing speed, and visual memory. These skills can be considered enhancers of the literacy process due to their significant impact on accessing the written language representation system. One limitation of this study, which would be interesting to consider in future research, is that attention was not paid to determining the level of stimulation the students may have received from their home environment, as this aspect could also be relevant for expanding the contributions of this research.

Funding

This work is part of the research and development project PID2022-139640NB-I00/AEI/10.13039/501100011033/FEDER, UE.

CRediT authorship contribution statement

Raúl Gutiérrez-Fresneda: conceptualization, methodology, formal analysis, investigation, writing - original draft, writing - review & editing. Teresa Pozo Rico: conceptualization, methodology, formal analysis, investigation, writing - review & editing. María Isabel de Vicente-Yagüe Jara: conceptualization, investigation, writing - original draft, writing - review & editing. Ester Trigo Ibáñez: conceptualization, methodology, formal analysis, investigation, writing - original draft.