Why Children Keep Some Toys, and What That Means for Circularity
By Sinem Halli
I am an industrial designer, and I am the mother of a preschooler. This started with my own son, long before it became research.
He went back to the same handful of toys over and over, and left the rest untouched, including the ones everyone had recommended. The ignored toys were not broken. They were well made. They just were not his. That gap nagged at the designer in me: what makes a child stay with a toy, and can we design for it?
I also have a degree in child development, so I started looking at the child and the object at the same time. And the further I went, the more this turned into a question about sustainability.
We usually talk about toy sustainability in terms of materials and end of life: what a toy is made of, whether it can be recycled, whether it can be reused or passed on. Circular economy, broadly, closes loops better than it slows them. Reuse and recycling get most of the attention, and where slowing the loop is discussed, it is usually framed materially, through durability and repairability. The behavioral side of slowing, why a person keeps using a thing, is rarely treated as a design variable (Halli & Kaya, 2026).
The use phase is where toys are lost
Toys make this gap unusually visible. Studies suggest that over 80 percent of toys are set aside within months of purchase (Nastase et al., 2022). Most are not thrown away and not broken. They sit at home, kept but unused (Champkins & Bocken, 2025).
That is a striking waste of resources when you consider what a toy is built for. Developmentally, a toy is meant to accompany its first child for two to three years; in material terms, a well-made one should be able to survive being handed down to two, three, or even more owners. By contrast, a few idle months is almost no life at all. And these toys did not fail because they broke. They failed because they stopped fitting the child.
From temperament to design
There are theories that explain why some objects hold on and others do not. Person-environment fit suggests that when a toy matches how a child plays, play lasts longer (Edwards et al., 2006; Zhang et al., 2025). Self-determination theory adds that toys supporting a child’s sense of competence and autonomy keep their attention (Koole et al., 2019). And emotional durability describes how familiarity and a sense of closeness keep a product relevant over time (Chapman, 2015; Desmet, 2002; Mugge, 2017). Together they point to the same place: an attachment that lasts because the object fits the child, not only because the material survives.
If fit drives use, the practical question is: fit to what? My answer is temperament. A child’s behavioral tendencies shape which design features keep them engaged. An extroverted child tends toward bright colors, warm tones, and interactive, social play; a more sensitive, anxious child tends toward cooler colors, soft and soothing textures, and calmer, sensory play (Halli & Kaya, 2026).
The work, then, is translation. Designers are translators by trade: we turn who someone is into something they can use. I gathered temperament research and organized it under the familiar Five-Factor vocabulary (openness, conscientiousness, extraversion, agreeableness, neuroticism), used here only as a shared language, not as a clinical label for a child. I then mapped those tendencies onto fifteen actionable toy design dimensions, such as color, texture, material, sound, interaction, and modularity (Halli & Kaya, 2026). The result is five design-facing personas: the Explorer, the Planner, the Performer, the Companion, and the Gentle.
What three studies show
Three peer-reviewed studies, with more than 650 Turkish caregivers in total, sit behind this.
The first looked at how caregivers actually choose toys, weighing eight sustainability criteria against best-selling toys on Turkish e-commerce sites, drawing on 220 caregivers (Halli et al., 2024). Educational and developmental value made up more than half of the basis for decisions, while durability and second-hand potential sat near the bottom, and price mattered less than expected. The study also found that online product pages barely communicate a toy’s sustainability and it concluded that long-term use is what really matters for sustainability in toys.
The second built a temperament-to-design framework, refined it with child-development and psychology experts, and tested it with 221 caregivers (Halli & Kaya, 2026). Caregivers whose child showed a dominant trait significantly preferred the toys the framework predicted for that trait, most clearly for extraversion and neuroticism (p < .001). Tellingly, even the best-matched toys on the market covered only 60 to 70 percent of the framework’s design profile, which says less about the framework than about how far commercial toys still fall short of temperament-aware design.
The third turned the framework into a working recommendation system, ToyMatch, and tested it with a separate sample of 214 caregivers (Halli, Kaya & Toreyin, 2025). Rather than ask caregivers to label their child, it uses a short, low-input flow built around the toys a child has already chosen, with a deliberately stereotype-neutral interface.
That last design choice matters more than it seems, and it answers a fair objection: in early childhood, the child is not the buyer. When I asked parents to describe their child’s temperament directly, the answers were noticeably biased; many reported a confident, untroubled, highly extroverted child. When I asked instead which toys the child actually reaches for, the signal was far less biased, and the matching held. The toys a child chooses are a more honest cue than a parent’s self-report.
These results are retrospective: the toys that stay in play longest tend to fit the child’s temperament. Whether recommending a fitting toy actually makes play last longer is the prospective question I am testing next, with a comparison group and play tracked over time.
Not only about toys
I do not think this is really about toys. A behavioral profile, a set of translation rules, and a library of design features: that pattern is not specific to temperament or to toys. My published work already points to adjacent areas where developmental fit matters, such as educational tools, child-centered furniture, and children’s apparel (Halli & Kaya, 2026). Where else do we need to translate who someone is into what an object should offer? I find that an open and useful question for circular design.
There is a production side to this as well. If a brand can see which children a toy actually fits, it can design and stock closer to real demand, and make fewer of the things that end up sitting unused. Reading behavior, rather than guessing at it, turns the same fit logic into a way to reduce overproduction, which is where the use-phase argument meets SDG 9 on resilient infrastructure, inclusive and sustainable industrialization, and innovation (Halli & Kaya, 2026).
For a circular economy, the shift is small but real. It moves the first question from “Is this product recyclable?” to “Does this product fit the person who will use it?” Recyclability still matters. But a toy that a child keeps playing with is, quietly, already doing the most circular thing a toy can do: staying in use.
I would be glad to discuss any of this, and to share the studies with anyone working across design, child development, and circularity.
Sinem Halli is an industrial designer and PhD researcher in the Department of Industrial Design at Istanbul Technical University (ITU), specializing in sustainable design. She holds a Master’s degree in Brand Communication Management, a B.Sc. in Industrial Design from ITU, and a B.Sc. in Child Development. An award-winning designer recognized internationally, including as one of Design Spirit Istanbul’s “40 Designers Under 40,” she has worked with global brands as both an industrial designer and a brand communication specialist, integrating sustainability across product and brand design. Contact: sinem@sinemhalli.com, sinemhalli@gmail.com
References
Champkins, M., & Bocken, N. (2025). Stimulating circulation in the circular economy: A case study of value generation for a resale platform for LEGO bricks. Journal of Cleaner Production, 516, Article 145505. https://doi.org/10.1016/j.jclepro.2025.145505
Chapman, J., 2015. Emotionally durable design. In: Emotionally Durable Design. Routledge, pp. 21–22.
Desmet, P., 2002. Designing emotions. Des. J. 6, 61–62.
Edwards, J.R., Cable, D.M., Williamson, I.O., Lambert, L.S., Shipp, A.J., 2006. The phenomenology of fit: linking the person and environment to the subjective experience of person-environment fit. J. Appl. Psychol. 91, 802–827. https://doi. org/10.1037/0021-9010.91.4.802
Halli, S., Kaya, C., & Arslanli, K. Y. (2024). Sustainability factors affecting caregivers’ toy preferences: An evaluation of e-commerce best sellers in Turkey. Journal of Consumer Behaviour, 23(3), 1285–1300. https://doi.org/10.1002/cb.2265
Halli, S., & Kaya, C. (2026). Temperament-based toy design for preschoolers: A persona profiling framework for cleaner production and consumption through emotional durability. Cleaner and Responsible Consumption, 22, 100434. https://doi.org/10.1016/j.clrc.2026.100434
Halli, S., Kaya, C., & Toreyin, B. U. (2025). ToyMatch: a temperament-aligned toy recommendation system for circular design in early childhoods. Frontiers in Sustainability, 6, 1668084. https://doi.org/10.3389/frsus.2025.1668084
Koole, S.L., Schlinkert, C., Maldei, T., Baumann, N., 2019. Becoming who you are: an integrative review of self-determination theory and personality systems interactions theory. J. Pers. https://doi.org/10.1111/jopy.12380.
Mugge, R., 2017. A consumers' perspective on the circular economy. In: Chapman, J. (Ed.), Routledge Handbook of Sustainable Product Design. Routledge, pp. 374–390.
Nastase, I. A., Negrutiu, C., Felea, M., Acatrinei, C., Cepoi, A., & Istrate, A. (2022). Toward a circular economy in the toy industry: The business model of a Romanian company. Sustainability, 14. https://doi.org/10.3390/su14010022
Zhang, Z., Zhang, W., Zhang, S., Chen, Y., Wang, X., Fujii, Y., Furuya, N., 2025. Person- environment fit theory in built environment: a scoping review. J. Asian Architect. Build Eng. 24, 2447–2463. https://doi.org/10.1080/13467581.2024.2373824.
