Numbers Speak Louder Than Words
As an optimiser I’ve conducted many Conversion Rate Optimisation (CRO) audits over the years. Heuristic rules are practical guidelines based on general observations about usability backed up by evidence. For example, above the fold content (i.e. content that doesn’t require users to scroll) is in many cases more likely to be seen and engaged with than content where the visitor has to scroll.
This is not universal, but it’s provable in many cases because evidence from scrollmapping software (e.g. Hotjar, Clarity, Mouseflow etc) often shows a proportion of visitors who don’t scroll at all. So a heuristic rule might be ‘key content like value propositions or calls to action should be above the fold’ because we know that not all users scroll.
One informal heuristic rule I’d used is that ‘numerically led USPs are easier to consume than text based USPs’. Examples of numerically led USPs might include:
- “Established since 1998”
- “Over 10,000 satisfied customers”
- “98% satisfaction rating”
It SOUNDS logical. But then I realised that I didn’t have any research to back this heuristic theory up. So I decided to do some investigation. It turns out there are a few pieces of academic research that support this rule.
1. Dual-Coding Theory
According to Dual-Coding Theory by Allan Paivio (1971), information is processed in two ways: verbally (words) and non-verbally (images or symbols). Numbers, because they are visually distinctive, can be encoded both verbally and visually, making them easier to recall compared to text alone. They create a “visual anchor” that provides a cognitive advantage in terms of memory retention.
For example, "98% satisfaction rating" may be remembered more easily than just "high satisfaction rating," as the number "16" provides a specific, quantifiable image in the mind.
2. Cognitive Load Theory
Cognitive Load Theory posits that information that is easy to process or "chunk" reduces the cognitive load on working memory. Numbers are processed more efficiently because they offer clear, succinct, and unambiguous meaning, allowing users to grasp the essential message quickly.
For instance, "100+ schools" immediately conveys scale and scope without requiring further interpretation, making it faster and easier to scan compared to a phrase like "a large number of schools."
3. Distinctiveness Effect
The Von Restorff Effect (also called the "Isolation Effect") explains that items that stand out from their surroundings are more likely to be remembered. Numbers in a text-heavy context are visually distinctive, often appearing in bold or larger fonts. This distinctiveness helps attract attention, making them more memorable than words.
A series of digits (like "5 steps" or "16 countries") stands out visually from the surrounding words and provides a natural focal point for the user’s attention.
4. Processing Fluency
Processing fluency refers to the ease with which information is processed. Numerical information tends to be more fluently processed because it is direct, unambiguous, and concise. High processing fluency leads to increased favorability in decision-making and more effortless cognitive absorption, which could explain why users might perceive numerically-led USPs as more appealing and easier to digest.
5. Impact on Decision-Making
Studies on bounded rationality and decision heuristics (e.g., Tversky & Kahneman) suggest that people rely on heuristics, like quantifiable metrics, to simplify complex decisions. Numerical claims such as “100+ schools” offer concrete, easily comprehensible data that reduce the effort required to compare alternatives. This suggests that numbers not only make information easier to process but also facilitate faster decision-making.
6. Numerosity Effect
The Numerosity Effect refers to the tendency for people to perceive numerical quantities as more significant than non-numerical descriptions. This means that numbers inherently carry weight and authority in the eyes of users, making them both easier to scan and more impactful on memory and decisions.
Empirical Evidence
Research on online behavior and eye-tracking studies shows that users tend to skim content rather than read it in detail. Numbers provide natural "visual hooks" that break up large blocks of text, leading to higher engagement and faster comprehension.
Font size, boldness, and spacing around numbers are often optimized in digital interfaces, making them more scannable than lengthy descriptions or paragraphs. While this may not always be specifically tied to memory, it certainly influences usability and attention.
In Summary
- Numbers create visual distinctiveness and make content more scannable.
- They are easier to process cognitively due to their concise and unambiguous nature.
- Memory recall is often improved because numbers can be visually and verbally encoded, and they benefit from the Von Restorff Effect.
- They can also aid decision-making by providing concrete, comparable data.