Debate on Quantity and Quality of Language Input: Which is more important? (9 critical insights backed by research)

Introduction

When it comes to language learning, the debate between quantity and quality of language input has been ongoing for years. Some argue that exposing learners to a large quantity of input is key to language acquisition, while others believe that focusing on the quality of input is more important.

I have had the opportunity to observe this recurring discourse between policymakers and language educators. Policymakers often emphasise the importance of focusing on the quality of language input as a means of improvement, as opposed to advocating for an increase in curriculum time. However, language educators argue that quantity of language input must increase (thus curriculum time to increase) to achieve the desired delta from the current state.

In this article, I shall contribute to this debate by presenting 9 critical insights backed by research. Whether we are language educators or learners ourselves, understanding the balance between quantity and quality of language input can greatly impact our language learning experiences. Without further ado, let’s get started and navigate through this longstanding debate.

What is QUANTITY OF LANGUAGE INPUT?

As with any good debaters, the very first step is to bring clarity to our keywords. What exactly is the QUANTITY OF LANGUAGE INPUT? In my previous article, I have defined it to be the extensive amount of exposure to language available that learners require for language development.

To put it simply, our learners need a substantial amount of input in the target language to gather enough “oxygen” to fuel the growth of language abilities in that language. Reading or listening to content in the target language is fundamental to kickstart representations of the language and its structures to be recognised as “learning” or “acquisition”.

Scholars have taken different approaches to define and measure “quantity”:

• Number of words/tokens/utterances: the total number of occurrences of a targeted linguistic unit as received by the learner within a given time frame (Anderson et al., 2021; Golinkoff et al., 2019; Hirsh-Pasek et al., 2015; Hoff, 2020; Jones & Rowland, 2017; Montag, Jones & Smith, 2018; Unsworth, 2016);
• Length of exposure: the amount of time a learner is exposed to the target language within the context(s) of measurement whether measured objectively (e.g. mean length of utterances) or reported subjectively (e.g. caregiver-reported exposure time in child age) (Bahrani, Tam & Zuraidah, 2014; Cohen, 2016; Cowan & Olmstead, 2023; Degotardi & Han, 2020; Gilkerson et al., 2018; Montanari, Steffman & Mayr, 2023; Pancsofar & Vernon-Feagans, 2006; Reynolds et al., 2019; Saito & Hanzawa, 2018; Thordardottir, 2011, 2019; Unsworth, 2016);
• Amount of curriculum/instructional time: the amount of time a learner receives instruction in the target language (Delaney, 2012; Saito & Hanzawa, 2018);
• Length of residence: the amount of time in which a learner has been residing in a country or region in which the target language is used in society (e.g. abundant supply of authentic input) (Moyer, 2009); and
• Proportion of exposure: especially in the context of exposure to more than one language in bilingual language acquisition (or even multilingual), essentially the percentage or ratio of one language to another (or others) within a given time frame (Cattani et al., 2014; Cowan & Olmstead, 2023; Kuo et al., 2020; Mieszkowska et al., 2017; Thordardottir, 2011).

Beyond these measures that are essentially methodological artefacts (that may have varying efficacies in capturing the actual real-life quantity received by the individuals), the main spirit underpinning QUANTITY OF LANGUAGE INPUT is that learners require amounts and amounts of the target language input (adding to a significant gross amount) to gain the necessary communicative competence and language skills. 

What is QUALITY OF LANGUAGE INPUT?

While quantity is somewhat related to the concept of volume and size, the notion of quality is multifarious. It can refer to the richness, complexity and accuracy of the linguistic data presented to our learners within any given time frame or context. Depending on various interpretations of “richness”, “complexity” and “accuracy”, it may be operationalised differently.

The main thesis within an argument on QUALITY OF LANGUAGE INPUT is that there is a differentiation between high-quality input and low-quality input. This differentiation isn’t strictly binary; it can manifest along a continuum with extremes at either end. Naturally, scholars advocating for the importance of language input quality place significant emphasis on the value of high-quality input.

So, how do scholars frame or measure “quality” in research studies? Below is a non-exhaustive list for our reference:

• Lexical diversity: the number of different words or lexical items that are found within a given sample of target language input received by a learner (Adamson et al., 2021; Anderson et al., 2021; Gao et al., 2023; Golinkoff et al., 2019; Hirsh-Pasek et al., 2015; Jones & Rowland, 2017; Leong, Trinidad & Suskind, 2023; Montag, Jones & Smith, 2018; Pancsofar & Vernon-Feagans, 2006; Plante et al., 2014; Reynolds et al., 2019; Unsworth, 2016; Unsworth et al., 2019);
• Syntactic Complexity: the degree of complexity in the syntactic structures characterising the language input received by a learner (Anderson et al., 2021; Gao et al., 2023; Hirsh-Pasek et al., 2015; Pancsofar & Vernon-Feagans, 2006; Reynolds et al., 2019; Rowe & Weisleder, 2020; Unsworth et al., 2019);
• Sources of input: basically the variability of the language input received by the learner in terms of the number of different speakers of the target language in frequent contact and the locations in which the language input is provided (e.g. home/school/community) (Cowan & Olmstead, 2023; Flege, 2009; Huang et al., 2020; Montanari, Steffman & Mayr, 2023; Piske & Young-Scholten, 2009b; Sinkeviciute et al., 2019; Unsworth, 2016; Unsworth et al., 2019);
• Contextul domains of use: the communicative situation or purpose in which the language input is positioned (e.g. e.g. formal/informal, knowledge-based/non-knowledge-based, concrete/abstract, language-driven/content-driven) (Cowan & Olmstead, 2023; Degotardi & Han, 2020; Hirsh-Pasek et al., 2015; Huang et al., 2020; Moyer, 2009; Rowe & Snow, 2020; Saito & Hanzawa, 2018; Unsworth, 2016);
• Degree of alignment with native speaker norms: the proportion of language input provided by native speakers (or L1 users) of the target language in relation to non-native speakers (or L2 users) which is sometimes operationalised as the number of speakers in frequent contact with the learner from either group (Bohn & Bundgaard-Nielsen, 2009; Budde-Spengler, Sachse & Rinker, 2021; Cowan & Olmstead, 2023; Flege, 2009; Golinkoff et al., 2019; Moyer, 2009; Piske & Young-Scholten, 2009a; Unsworth, 2016; Unsworth et al., 2019); and
• Types of input appropriate to learner profile: the extent to which there are various types of language input to address the diverse learning demands of the learners (e.g. modified input such as child-directed speech or baby talk for preschoolers, naturalistic input for authentic application of use for adult learners) (Barcroft & Wong, 2013; Doughty, 2003; Gao et al., 2023; Golinkoff et al., 2019; Hirsh-Pasek et al., 2015; Kane et al., 2023; Rohde, 2009; Rowe, & Snow, 2020; Rowe & Weisleder, 2020).

While these are some of the most commonly studied aspects of quality, let’s be mindful that this is by no means an exhaustive compilation of the potential expressions of quality. We would not be too surprised if future research endeavours zoom in to unexplored dimensions of language experience that have not taken centre stage today.

Critical Insights from research on the QUANTITY and QUALITY of LANGUAGE INPUT

Now that we have understood what both QUANTITY and QUALITY of LANGUAGE INPUT refer to, let’s move on to the critical insights that we should work into our equation as we plan our curriculum and pedagogical approaches.

1. Quantity is important, but it is not the case of the more the better.

Let’s get one very important finding stuck in our minds: the role of input is indispensable. It is the fundamental ingredient to kickstart any process of language acquisition. I believe we are all sober enough to not fantasise that we can attain proficiency in a target language with zero exposure to that language.

This is why quantity of language input is important – an argument established and substantiated by an extensive body of research evidence (Blom, 2010; Cohen, 2016; Flege, 2009; Hart & Risley, 1995; Gilkerson et al., 2018; Golinkoff et al., 2019; Kuo, Ku, Chen & Gezer, 2020; Montag, Jones & Smith, 2018; Leong, Trinidad & Suskind, 2023; Montanari, Steffman & Mayr, 2023; Rowe & Snow, 2020; Saito & Hanzawa, 2018; Thordardottir, 2019; Unsworth, 2016; Unsworth et al., 2019). Even for bilingual children, research has also demonstrated a correlation in the quantity of input and a faster rate of language development (Unsworth, 2016). If the volume of input is the key to language learning, why not saturate our learners with input in the target language to the maximum extent that reality allows?

If only it was that straightforward. Let me illustrate one scenario: would we realistically anticipate a significant boost in our learners’ receptive and expressive skills in our target language(s) after subjecting them to a 10-hour auditory marathon of ‘Hello’ and ‘Thank you’ in that/those language(s)? It’s a question that beckons our attention.

Scholars who have examined this question brought us some interesting findings:

• Despite moving to and residing in a country or region where the target language is widely used (e.g. main societal language), there are many learners who did not gain much mastery of that target language (Moyer, 2009);
• The quantity of language exposure to the dominant societal language within the home environment through parental effort did not show any significant correlation with their children’s language development outcomes (Unsworth, 2016); and
• Notwithstanding significantly higher amount of exposure to preferred audiovisual programmes, low-level adult learners did not experience any significant progress in their language learning outcomes in contrast to fellow intermediate-level learners (Bahrani, Tam & Zuraidah, 2014).

Riding on the last finding in this list, I sometimes find myself cringing when people suggest that binge-watching dramas in the target language is an effective method for language learning. I won’t dismiss the potential benefits, but rather to question the notion that watching 60 hours of Korean drama would suffice to trigger cognitive and linguistic growth into an intermediate-level communicator in the language. This argument lacks persuasiveness unless we consider mastering a few formulaic expressions such as ‘annyeong haseyo’ and ‘saranghaeyo’ alongside an array of profanities, as an accomplishment deserving of an intermediate level.

2. When quantity is past a certain threshold, quality matters.

Ok, so we know that quantity matters, yet it is not the case of the more the better. Why so? Quality comes into the picture. When quantity is guaranteed to a certain threshold, quality becomes a stronger predictor of language learning gains (Anderson et al., 2021; Bahrani, Tam & Zuraidah, 2014; ; Golinkoff et al., 2019; Jones & Rowland, 2017; Rowe & Snow, 2020; Unsworth, 2016).

I guess we should not be too surprised about this. Regardless of our preferred definition of language, most of us would view language learning fundamentally as a process of gaining various aspects of linguistic knowledge (across the various components of the language system) and acquiring skills to be able to use it effectively.

For that to happen, within any given sample of input (e.g. fixed quantity), we should expect to effect learning focused on different aspects of language and thus manipulating the various “qualities”. A guiding principle is to review the profile of our learners and refer to the list of “qualities” in the earlier section to devise language input design strategies that cater specifically to the needs of our learners.

Perhaps one mind-boggling question would be: what is the threshold then? As with many scientific research, there is no one universal answer for all situations. Personally, I have yet to encounter research studies that proposes an absolute quantity, regardless of dimension used, as the threshold (would love to find out more if you do have any).

However, research zeroing in on language input in bilingual language development (or even multilingual acquisition) does give us some hints to that threshold in terms of proportion. In these studies, language development of bilingual (or trilingual) children was comparable to their monolingual peers for a target language despite receiving less exposure at around 40 – 60% in terms of proportion (Cattani et al., 2014; Thordardottir, 2011, 2015; Unsworth, 2016). With bilingualism or multilingualism more as the norm rather than the anomaly, this can be thought-provoking for us as we work with our learners.

3. Quantity is fundamental before we can talk about quality; quality and quantity are strongly correlated.

Considering the fact that the quantity of input alone cannot elucidate the full spectrum of differences in language development, and acknowledging that an increased amount of input doesn’t invariably yield superior performance, does that also suggest that our attention should be directed towards the quality of language input? Notably, there are scholars who do make the explicit argument that the importance of quality surpasses that of quantity based on their specific studies (Bahrani, Tam & Zuraidah, 2014; Delaney, 2012; Golinkoff et al., 2019; Jones & Rowland, 2017; Rowe & Snow, 2020).

Even so, these scholars did not chant the “quality above all” mantra. While I highlight the inadequacy of “quantity” in explaining all the difference in language development in the earlier sections, I am also not trying to suggest that quantity is less important than quality. In fact, I want to highlight that quantity is the basis for any discussion of quality. In a sense, quality is contingent on having quantity in the first place.

At the very minimum, if we find ourselves granted no more than a mere hour each day within the curriculum for a target language which is not even a societal language (I know some of us have it worse with only an hour a week), where can we discover the room to earnestly strive for an improvement in the richness and complexity of our language input? How do we find space to augment the lexical diversity, syntactic complexity or various sources and types of input? It is akin to ask a cook to make a award-winning Michelin dish by giving only a few ingredients.

Quantity of language input needs to be guaranteed first. Not to say that there is little to do with limited quantity, but the quality of input improves only when there is room in quantity. As a matter of fact, majority of research studies encounter difficulties when attempting to disentangle quantity from quality, especially when quantity of input is generally strongly correlated with quality in natural, real-world situations (Degotardi & Han, 2020; Hoff, 2020).

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4. The notion of high quality may be dynamic and change with age or learning experience.  

We know that quality is important. While the improvement of quality can be contingent on quantity, we could still seek to improve the quality of language input even when quantity is limited.

To put it in another way, if we are forced by circumstances to only work with a limited amount of input (e.g. the limited curriculum time allocated to our language lessons), then making every second and every word counts becomes paramount.

However, while research painted a list of “quality” aspects (as found in the definition), it has also informed that the concept of high quality in language input is not static but rather dynamic, one which evolves with age and learning experience.

For a start, young learners (e.g. toddlers, children) and novices (e.g. people who just started the learning of a foreign language) may benefit from more consistency within input than diversity (Flege, 2009; Golinkoff et al., 2019; Montag, Jones & Smith, 2018; Sinkeviciute et al., 2019; Unsworth, 2016). This means lower levels of lexical diversity, syntactic complexity (e.g. more repetition) accompanied with more simplified input (e.g. foreigner talk / baby talk, formulaic expressions) largely from the target language exemplary models (L1 users or native speakers). During this stage, consistency allows this group of learners to make sense of the commonalities found within the input to form their baseline representations.

However, as the learners progress (e.g. the theoretical input quantity threshold hit), the importance of diversity and variability takes precedence. It’s no surprise: once our learners have expanded their vocabularies and conquered the fundamental building blocks of language, they must tackle the more challenging ones to be then able to move up to the next level. Even for those who receive instruction in a foreign language, typically in a classroom setting, experts recommend seeking out authentic input outside of school to achieve even better learning outcomes (Huang et al., 2020; Saito & Hanzawa, 2018).

5. Differential input between a repertoire of languages in terms of quantity and quality can result in varying outcomes in bilingualism.

The ongoing debate over whether quantity or quality holds more weight is already intense and intricate when we focus on a single language or a monolingual setting. But guess what, when we step into the territory of bilingualism, or even multilingualism, things get even more convoluted.

I have presented earlier, using research findings on input quantity and quality within the context of bilingualism, on the proposed threshold in proportion of language exposure for bilinguals for them to perform comparably with their monolingual peers using the same target languages.

What this generally means is that quantity matters for every single language within the repertoire – differences between quantity, especially those that has yet to hit the threshold, may expect overall performance below that of monolingual peers using the same target language(s) (Unsworth, 2016). This has been the case of home languages of migrant families which are also minority languages (Mieszkowska et al., 2017).

Below the threshold, differences in quantity can bring about differences in the outcomes of bilingualism. The same principle applies when we consider the impact of quality. Particularly, researchers have discovered specific dimensions that have an influence on the outcomes (Cowan & Olmstead, 2023; Hoff, 2020; Huang et al., 2020; Unsworth, 2016; Unsworth et al., 2019):

• Lexical diversity: mixed findings were found in the extent of lexical diversity in one of the languages in a bilingual child’s repertoire, possibly due to interacting factors such as whether the language is a majority / minority language or whether it could be a function of the age and current proficiency level of the child;
• Syntactic Complexity: similar to the findings on lexical diversity;
• Sources of input: whether or not the bilinguals are able to receive sufficient input of their target languages from a good variety of speakers to be resilient to within-language variability (e.g. able to adapt to different idiosyncrasies and dialectal differences);
• Degree of alignment with native speaker norms: whether or not the bilinguals / multilinguals have enough input from native speakers or L1 users (which can include non-native speakers with L1 proficiency); and
• Types of input appropriate to learner profile: the extent to which there is sustained input in various types that necessarily maintains the fuel for upkeeping of the different languages in the repertoire while providing critical linguistic data to trigger further growth.

And so, if we are language educators dealing with bilingual / multilingual learners or that we are operating in such contexts (which is probably the norm), we should recognise that other than attending to the quantity allocated to languages in their repertoire, we could also invest in managing the qualities of those exposure.

6. Reading is an important activity that can increase both quantity and quality in the long run.

Contemporary language instruction has witnessed a notable shift toward communicative-based approaches, with a clear emphasis on cultivating interactive oral communication skills. This prioritisation of oracy is particularly evident in second language and foreign language education contexts.

If we happen to be operating in this school of thought, I do hope we can reflect further on how we can make space for reading instruction. Remarkably so, reading as an activity and habit has been proven to be associated with the following benefits:

• Parent-child shared reading activities encourage dialogues that incorporate a higher level of lexical diversity and syntactic complexity in a process which brings salience to form and meaning to the child (Golinkoff et al., 2019; Rowe & Snow, 2020);
• When a learner is literate, reading serves as a sturdy foundation for expanding his/her vocabulary and a stable source of authentic naturalistic input (Rowe & Weisleder, 2020) and we can tap on the affordances of literature to capitalise on this;
• A learner with reading habits and willing to read extensively in the target language(s) would be able to maintain the language (i.e. resilient to language attrition) even after instruction has ended, especially when that language is not a widely used language.

Despite these benefits, I would like to highlight that reading needs instruction – it is not something that can be developed naturally without proper intervention.  Mere reading to children as a form of input can be considered as a measure to increase input quantity without care to quality. For more insights on reading, you can continue reading this article (pun intended).

7. Variance in quantity and quality of input received by individuals is very much correlated with their socioeconomic status.

For many of us, I believe, we don’t really choose who enters our classrooms and become our learners. We remain wholeheartedly committed to the academic growth and development of any individual who enter our classrooms, regardless of the circumstances they may have come from.

And so, I need to highlight one pertinent finding: the variance in both the quantity and quality of input our learners receive is generally closely linked to their socioeconomic backgrounds. Research has shown that there is a significant difference in the language exposure that children from low-income families receive compared to their peers from higher-income households (Gilkerson et al., 2018; Hart & Risley, 1995; Hirsh-Pasek et al., 2015; Leong, Trinidad & Suskind, 2023) – in a manner characterised by both reduced quantity and inferior quality.

Put simply, the socioeconomic status of our learners can serve as an early warning sign for potential challenges in their linguistic development due to disparities in their home environments. The coining of the term “30-million-word gap” (Hart & Risley, 1995; Hirsh-Pasek et al., 2015) is a vivid representation of such disparities and is something that we should be very concerned about in achieving more equitable educational outcomes. 

What could have caused the difference? Caregivers from families of lower socioeconomic status are often confronted with obstacles in creating enriching language environments, characterised by the usage of fewer words, limited vocabulary, and less sophisticated language during interactions with their children. On top of that, the learners from these families have fewer formal opportunities for language learning in contrast to their privileged peers.

That is why we play a very important role in bridging such differences. Apart from our direct work with students to narrow this gap, it is also beneficial to channel our efforts into fostering a strong parent-teacher partnership to support our parents in this endeavour.

8. Maintenance in quantity and quality of input received is important in the maintenance of proficiency.

Much of the research on quantity and quality of input may converge on the significance of input matters at the early age. In other words, it can create the impression that input during the early years is the key determining factor of latter language development.

Not to dispute that – I have shared many findings from longitudinal research that point to the value of language input rich in both quantity and quality in child language to be associated with the language educational outcomes later on.

However, when scholars sought to distinguish whether early-age input effects last till later stages in life when either quantity or quality is reduced, the findings seem to suggest that sustenance of input in both quantity and quality is required on a long term to maintain the same level of proficiency, if not improving it (Hoff, 2020; Huang et al., 2020).

In essence, language proficiency is not a static entity, but a dynamic skill that requires regular practice and meaningful exposure to avoid degeneration. This is very much aligned with the research on language attrition (link), though the interacting forces with competing languages for bilinguals / multilinguals may also play a role. For a target language to be “kept alive”, it needs continued sustenance both in quantity and quality to enable the neural networks related with using that language to be actively stimulated. This can be an inherent challenge if our target language belongs to a language minority within the society (e.g. heritage language). 

9. Parents and Language educators make a real difference to the various aspects of quantity and quality of language input.

Ok, this is not exactly an unexpected insight. I would be surprised if we are not cognisant of this. Nevertheless, it is still a critical insight to then emphasise the crucial role of investing in professional learning pertaining to language input and its incorporation into our language teaching methodologies. Equally vital is our collaborative engagement with parents, conducted with the aim of offering a supportive experience rather than burdening ourselves or them.

But there may be gems in this critical insight that I have not mentioned earlier and are less straightforward. First, the nuances for parents below:

• Parent-child shared book reading is extremely important as it augments the quantity and quality of parental input when there is “dialogic reading” involved – abundant interactive question-and-answering between parent and child (Golinkoff et al., 2019; Reynolds et al., 2019);
• Pertaining to the quality and quantity of parental linguistic input, there are some significant differences between mother-provided input and father-provided input generally in terms of length, vocabulary use, complexity of language, and the type of questions – fathers tend to provide less in amounts, use rarer vocabulary but shorter sentences, and more open-ended wh-questions (Pancsofar & Vernon-Feagans, 2006); and
• Most findings highlight parental linguistic input (from both fathers and mothers) to significantly predict language (e.g. child vocabulary, morphosyntax) and overall educational development (e.g. math ability) in the child later on, although some found the variance in father-provided input to play a larger role (Pancsofar & Vernon-Feagans, 2006; Reynolds et al., 2019).

For language educators, we can celebrate that we do make a difference. Let’s work on the following though:

• We should aim to provide various types of language input that are tailored to our learners’ current needs as they can potentially expedite the rate of acquisition (Barcroft & Wong, 2013; Benati, 2016; Doughty, 2003);
• While language input provided in the classrooms has a role in learning second language or foreign language, learners would need to guided to access and sustain the attention to naturalistic input in out-of-classroom contexts for longer-term development (Huang et al., 2020);
• Attending to content in language input as part of language learning has potential benefits, although we can hardly assert that content-based instruction is thus more superior than form-focused instruction (Saito & Hanzawa, 2018);
• Teacher talk that provides opportunities for further interaction and extends the negotiation of meaning beyond the immediate apparent context (e.g. illustrating an object with details that are not seen in the immediate image) has higher potential of effecting quality language growth (Kane et al., 2023); and that
• We should seek to provide more input through talking (e.g. increasing quantity) in the early years if our learners are not acquiring the target language as a first language and to also maintain consistency and simplicity instead of expanding diversity or deepening complexity in language use (e.g. managing quality), although we could slowly calibrate accordingly as our learners develop their language abilities (Unsworth, 2016).

To bring it all together, let’s remind ourselves that we can have a significant impact on the quantity and quality of language input that our learners receive. Striking the right balance, considering individual learner differences, and providing meaningful and engaging experiences are crucial for optimal language acquisition. By staying informed and continuously improving our teaching practices, while also factoring in our learners’ home language input environment, we can truly enhance the language learning experience of our  learners.

Conclusion: Which is more important for LANGUAGE INPUT – QUANTITY or QUALITY?

By this point, I hope the answer to this question is very salient: both quantity and quality are important. Where the amount of input is so impoverished, we should aim to augment the quantity as the first priority; and when there is some quantity – even if limited, we should pay attention to the quality suited to our learner profiles. So indeed, quantity and quality of language input are as important, especially since both are correlated (Degotardi & Han, 2020; Hirsh-Pasek et al., 2015; Montag, Jones & Smith, 2018; Piske & Young-Scholten, 2009a; Unsworth, 2016; Reynolds et al., 2019).

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