The law of uniform connectedness: what looks connected is read as a unit
Elements connected visually tend to be perceived as related.
In ecommerce, an interface does not exist in isolation. It exists within a specific task: finding something, understanding it, comparing it, deciding whether it is worth it, and completing an action. That is why a UX principle only becomes useful when it can be translated into observable behaviour.
01 / THE PRINCIPLE
Elements connected visually tend to be perceived as related.
The important idea is not to turn the principle into a mechanical rule. It is to use it as a lens for looking at an experience and identifying where the design is making a task easier and where it is transferring unnecessary work to the person.
02 / WHEN IT APPEARS IN ECOMMERCE
A product card, its variant selector and its price need to show clearly what belongs together. Poor visual connection can cause selection errors even when all the data is correct.
In a digital store, the same principle can appear on the homepage, in a category, on a product page, in the cart or after purchase. Its effect changes according to the context because the person's goal changes too.
03 / THREE COMMON SITUATIONS
- A price sits too far from the variant that changes it.
- A CTA appears to belong to the wrong product.
- A promotion looks linked to several products when it applies to only one.
04 / THE DESIGN MISTAKE
The common mistake is to apply the principle as a recipe. A designer identifies a rule, turns it into a component and considers the problem solved. But behaviour does not work that way.
The same decision can help in one situation and hurt in another. Highlighting an element can improve attention or turn a page into noise. Reducing options can make a decision easier or hide necessary alternatives. Adding information can increase trust or increase cognitive load.
That is why the principle must remain subordinate to the task.
05 / WHAT THE SYSTEM SHOULD DO
Use proximity, lines, backgrounds and grouping to express real relationships. The interface should make the structure of the data visible.
The question is not simply what the interface can do. The question is what work the system should take on so that the person can devote their attention to the decision that actually matters.
In ecommerce, this often means organising before showing, explaining before asking, preserving before making people repeat themselves, and providing feedback before doubt appears.
06 / FROM PRINCIPLE TO BEHAVIOUR
A good application of the principle should be observable in something concrete.
A person may find a product sooner. They may revisit the same pages fewer times. They may make fewer errors. They may complete a form with fewer corrections. They may abandon less often during checkout. Or they may understand more clearly why one alternative is appropriate.
If we cannot connect the design change to a behaviour, we are probably still talking about aesthetics or opinion rather than experience.
07 / WHAT TO MEASURE
Measure selection errors, variant changes, CTA clicks and questions about terms.
Not every metric has to improve at the same time. A reduction in time can be positive if it preserves decision quality, but negative if it leads to incorrect purchases or more returns. The metric must be interpreted within the business objective and the behaviour we are trying to facilitate.
08 / A SIMPLE CASE
Imagine a category with fifty products.
The system can show all fifty from the beginning and rely on the user to find the right one. It can also help them define a need, reduce the set of alternatives and then present the relevant differences.
Both systems contain the same products.
The difference lies in how much work the person has to do to reach them.
That is where the principle stops being theory and becomes design.
09 / THE UNCOMFORTABLE QUESTION
Can someone understand what belongs together without reading every word?
This is the question worth bringing into a UX review because it forces us to move from “I like how this is designed” to “I know what behaviour I am trying to produce and why”.
10 / CONCLUSION
UX principles are not magic conversion buttons.
They are models for observing how people interact with systems.
In ecommerce, that observation has a concrete consequence: every interface decision changes the effort required to buy.
Better design does not mean eliminating all effort.
It means reserving effort for the decisions that actually deserve it.
Reference principle
This article is based on the corresponding principle published by Laws of UX and develops it originally from the perspective of UX, behaviour and ecommerce.
The conceptual reference does not replace research into the actual behaviour of each product or business.