Seeing savings differently: Can an optical illusion help small savers save more?

If someone asked you whether two identical dark circles drawn on a page are the same size, you would probably say yes. But place one inside a slightly larger ring and the other inside a much bigger ring, and your brain would almost certainly tell you the first circle is bigger. That is the Delboeuf Illusion, named after the 19th-century Belgian philosopher and mathematician Joseph Delboeuf.

According to Prodeepto Chatterjee, Deputy General Manager at the Pension Fund Regulatory and Development Authority (PFRDA), this illusion may hold a key to solving one of the most stubborn problems in personal finance: getting people, particularly small savers like gig workers, to save more.

In an article published in PFRDA's Pension Bulletin for April-June 2026, Chatterjee explains that the illusion works through two psychological principles.

• The assimilation effect: When the surrounding ring is close and only slightly larger than the central disc, the disc appears bigger than it actually is.

• The contrast effect: When the surrounding ring is far and much larger, the disc looks smaller.

Chatterjee points out that the optical illusion concept "extends far beyond simple visual puzzles." He says empirical studies have shown that "even something as mundane as the design of serving ware can affect how much food we serve ourselves."

People tend to overestimate food portion size when it is presented on plates with wider or coloured rims. Buffet plates in restaurants are often smaller than a la carte plates, an intentional design choice so that diners consume less at a fixed buffet price but order more when paying per dish.

While the Delboeuf illusion has been traditionally studied in the context of physical quantities like food portions, Chatterjee says its underlying principles of visual bias can be extended to influence the perception of abstract financial quantities and decision-making.

"If the Delboeuf illusion can make a physical quantity appear larger or smaller, it can potentially be adapted to make a numerical quantity, such as a small savings contribution, feel larger and more significant, or a substantial debt feel smaller and more manageable."

The real insight of the article is in how Chatterjee combines the ideas of Delboeuf's illusion and gamification. A small saver, he suggests, could be presented visually surrounded by a slightly larger, closely placed "goal" circle, so that the assimilation effect makes the contribution feel bigger than it is. A ₹200 saving shown as a nearly full small circle would feel like "almost done" rather than "barely started" if it were shown in a large, partially filled circle.

Similarly, a budgeting app could display ₹50 spent on dining out in a large, hollow ring, making it seem insignificant, and the same ₹50 saved in a small, filled ring, making it seem substantial, nudging the user to prioritise saving. For large debts, the contrast effect could work in reverse: presenting the debt amount inside a much larger "total financial picture" circle could make the debt feel smaller and less overwhelming, reducing financial stress and encouraging consistent repayment.

For the average small saver, the takeaway from Chatterjee's article is not about waiting for the perfect app. It is about recognising that the way we frame savings visually and emotionally changes how motivated we feel. For example, a ₹100 daily saving shown as ₹3,650 a year feels different from the same amount shown as a daily drop in an ocean. Progress bars, milestone trackers, and visual goal markers are not gimmicks; they are tools rooted in how the brain actually processes motivation.

Chatterjee says, "By making financial progress not just numerical but also visually and emotionally rewarding, this integrated approach shifts savings from a perceived chore to an engaging game."