A three minute prompt to talk: Boosting parent-infant verbal engagement at low cost

Why talking to babies matters – and why scaling up is hard

Around the world, parents coo, sing, and soothe their babies. But fewer families engage in ‘richer talk’: responding to babbles, using varied words, and speaking in simple sentences. Yet talking to babies matters: these early conversations are critical for language and cognitive development (Monnot 1999, Weisleder and Fernald 2013).

Research shows that the amount and richness of infant-directed speech vary with socioeconomic status, both within and across societies (Hart and Risley 1995, Hoff 2003, List et al. 2021). Because these conversations play such a central role in early development, gaps in parent-infant talk are likely to compound the disadvantages faced by children in poorer families. The challenge is particularly acute in low-income countries, where over 250 million children under five are at risk of not reaching their developmental potential (Black et al. 2017). In Northern Ghana, for instance, only 11% of mothers believe parents should start talking to babies from birth (Duflo et al. 2024). If parents wait until children can respond, they miss a critical window when the brain is developing most rapidly.

A growing body of work shows that programmes encouraging ‘responsive‑caregiving’ can raise parental knowledge and shift behaviours with lasting benefits. But most of these programmes are intensive, delivered through repeated home visits, and expensive to scale (Jeong et al. 2018, Jeong et al. 2021). One key challenge now is to find approaches that work while also being affordable and scalable (Justino et al. 2023). Recent efforts, such as programmes using automated phone calls, have had mixed success (Arteaga et al. 2025).

A light-touch prompt on the importance of talking to babies

Our research (Dupas, Falézan, Jayachandran, and Walsh 2025) tested a simple idea: could a three-minute animated video plus a wall calendar with visual reminders help mothers see the value of talking to infants and encourage them to do so? To test the idea, we conducted a randomised control trial in Northern Ghana. Our intervention combined two elements:

• A three-minute animated video, shown to pregnant or new mothers during routine prenatal or postnatal visits at clinics. The video explained that infants learn from hearing words directed at them, even before they can talk back. It offered practical suggestions such as narrating daily chores, singing songs, telling stories.
• A wall calendar, handed out at the same visit, reinforced the message with images from the video and weekly stars that mothers could colour in when they talked to their baby each day.

We enrolled over 1,400 women and randomly assigned half to receive the video-plus-calendar package. The control group just received a placebo calendar without any messaging.

Early evidence of change in beliefs and behaviours

Six to eight months after the intervention, we surveyed mothers asking about their beliefs, behaviours, and infants’ development. We also added more objective checks: surveyors noted whether children babbled and conducted a short development assessment. We also used small wearable audio recorders, worn by children in a specially designed shirt, to capture a full day of the child’s auditory environment.

On self-reported outcomes, the full chain of effects appears: 

• Mothers’ beliefs: Mothers who watched the video were more likely to endorse early talking as key for development. For instance, they were 10 percentage points more likely to say parents should start talking to babies from birth.
• Parents’ behaviours: Consistent with a shift in beliefs, mothers reported doing more conversational activities, such as looking at books with their infant (+7 percentage points) and telling stories (+5 percentage points).
• Infant’s early skills: Infants scored higher on language and gestural communication. On simple vocabulary checks, mothers reported children understood 7% more words and also said more.

On objective measures, the results were positive but less precise. Surveyors were around 5 percentage points more likely to hear treated infants babble during their visit, but broader developmental indices did not show clear differences. Audio recordings also suggested increases in adult words directed to children, though budget constraints limited this sample and made estimates imprecise.

A ‘day‑after’ test shows what’s possible

A concern is that even if parents learn that talking to babies matters, this shift in beliefs may not translate into daily practice. Perhaps mothers feel awkward or find it too difficult to fit into daily routines. To test this, we conducted a within‑household ‘endline intervention’ with a subset of mothers who had not seen the video. After an initial day of recording, we showed the video and recorded again the next day. Mothers immediately increased the words they spoke to their infants by roughly 8–9%. Male adults in the household also spoke more to infants. 

This sharp short-run increase shows that mothers know how to engage once told: there is no ‘technological barrier’ to talking to babies. The challenge is sustaining the new behaviour over time.

Why does behaviour fade? Norms give way, habits are hard

When we asked about barriers, newly informed mothers most often mentioned fear of social scorn. Months later, that concern had largely dissipated, but many still said the main challenge was forming a habit. First‑time mothers—who lack entrenched routines—were less likely to report habit‑formation as a barrier and tended to show larger gains. Colouring the weekly stars on the calendar correlated with bigger effects, consistent with the need for habit support.

What it costs – and how it compares

In our trial, the intervention cost around $3 per child. At scale, using existing clinic staff, the cost would fall to just $0.45 per child. This makes it one of the cheapest tested ways to improve early language development. If we compute costs relative to the improvements we measure, the programme comes out as highly cost-effective.

For comparison, a recent review of 12 early-childhood programmes found the median programme cost $328 to deliver similar developmental gains (Verguet et al. 2022). Even if the real-world impact were only a fraction of what we estimate, this light-touch approach would still be far more cost-effective than most existing programmes.

Policy takeaways for early childhood development

• Use routine clinic visits as a delivery platform. A short video and visual reminder can be slotted easily into existing maternal and child health visits, keeping costs minimal.
• Pair information with habit support. Information ‘lands’ immediately, mothers respond immediately to the video, but sustaining change is hard. Simple habit supports such as weekly check‑off calendars or commitment prompts would likely help make daily talk a habit.

What we learned about designing ‘light‑touch’ parenting interventions

Our study shows that tiny, well-timed information prompts can shift beliefs and parenting practices in a low-income context – and plausibly improve early language development – at low cost per child. One key insight is that information matters, but may not be sufficient: the remaining challenge is helping parents turn new intentions into lasting habits.

For policymakers, the lesson is clear: existing clinic visits can be used to deliver low-cost videos and reminders. Testing simple habit tools – such as planning prompts or brief follow-up messages – could make effects last. With over 250 million children worldwide at risk of not reaching their developmental potential, scaling such light-touch approaches offers a promising way to close early gaps affordably.

References

Arteaga, I, A de Barros, and A J Ganimian (2025), “The challenges of scaling up effective child-rearing practices using technology in developing settings: Experimental evidence from India,” Journal of Research on Educational Effectiveness.

Black, M M, S P Walker, L C H Fernald et al. (2017), “Early childhood development coming of age: Science through the life course,” The Lancet 389(10064): 77–90.

Duflo, E, P Dupas, E Spelke, and M Walsh (2024), “The intergenerational effects of secondary education: Experimental evidence from Ghana,” Unpublished manuscript.

Dupas, P, C Falezan, S Jayachandran, and M Walsh (2025), “Informing mothers about the benefits of conversing with infants: Experimental evidence from Ghana,” American Economic Journal: Economic Policy 17(2): 388–417.

Hart, B, and T R Risley (1995), “Meaningful differences in the everyday experience of young American children,” Paul H. Brookes Publishing.

Hoff, E (2003), “The specificity of environmental influence: Socioeconomic status affects early vocabulary development via maternal speech,” Child Development 74(5): 1368–1378.

Jeong, J, H O Pitchik, and A K Yousafzai (2018), “Stimulation interventions and parenting in LMICs: A meta-analysis,” Pediatrics 141(4): e20173510.

Jeong, J, E E Franchett, C V R de Oliveira, K Rehmani, and A K Yousafzai (2021), “Parenting interventions to promote early child development,” PLoS Medicine 18(5): e1003602.

Justino, P, M Leone, P Rolla, M Abimpaye, C Dusabe, D Uwamahoro and R Germond (2023), “Improving Parenting Practices for Early Child Development: Experimental Evidence from Rwanda”, Journal of the European Economic Association 21(4): 1510-1550.

List, J A, J Pernaudet, and D Suskind (2021), “It all starts with beliefs: Addressing the roots of educational inequities by shifting parental beliefs,” Unpublished manuscript.

Monnot, M (1999), “Function of infant-directed speech,” Human Nature 10(4): 415–443.

Verguet, S, S Bolongaita, A Morgan, N Perumal, C R Sudfeld, A K Yousafzai, and G Fink (2022), “Priority setting in early childhood development: An analytical framework for economic evaluation of interventions,” BMJ Global Health 7(6): e008926.

Weisleder, A, and A Fernald (2013), “Talking to children matters: Early language experience strengthens processing and builds vocabulary,” Psychological Science 24(11): 2143–2152.