All things that have been designed communicate, but using redundancy to convey this information through different sensory modalities can improve user experience.

A world without redundancy


One of my favorite moments of the day is the train journey from home to the office. During that time I try to sleep. Some months ago, however, something was missing. Suddenly I realized that the voice announcing the next station didn’t work. This forced me to open my eyes continuously to check if I had already arrived to my station.


Some weeks ago, I downloaded a meditation app to my smartphone. I connected the headphones, turned off the lights and initiated the application. One day, however, I decided to change the order of these steps: First, I turned off the lights and then I connected the headphones. Problem: My headphones have two outputs, one for audio and one for the microphone. In the dark I wasn’t able to distinguish which one was the audio.


I sometimes work in the living room. I like its warm soft light. I turn my laptop on and when I try to plug it … I always have to use a flashlight because it’s impossible to see the orientation in which I have to connect the plug.

Electric vehicle

Electric cars are extremely quiet and they are almost completely silent when they’re moving slowly. The US, Japan and the European Union have approved legislation that requires the use of alert sounds for all new electric vehicles to allow pedestrians to detect them.

Redundancy, error and noise

The train, the headphones, the socket and the electric vehicles are examples in which the interaction between product and user fails due to the absence of redundancy.

In communication, redundancy refers to the information that appears more than once. It’s usually associated with inefficiency, as it consists of repeating the same piece of information. However, far from being superfluous or unnecessary, redundancy is essential to reduce confusion and ambiguity.

Any system in which information is transmitted from a sender to a receiver must face two problems: errors and noise. Errors occur when part of the information is incorrect, while noise refers to external information that interferes with the message. Both distort the original message and hinder its correct interpretation by the receiver.

Redundancy allows us to correct errors and reduce the impact of noise because, by repeating the information, a system ensures that at least the essential part of the message will come to the receiver, so that it will still be possible to be understood.

Even the DNA uses redundancy to reduce the impact of possible errors (mutations) generated in the genetic code. Examples of redundancy are also found in the written language, where many of the letters, in fact, do not provide essential information. That is why you can read correctly this sentence:

If u cn rd ths msg…

Redundancy in design

Products and services also communicate. Whether intentionally or not, all things that have been designed convey information about what they are for and how we can use them. Thus, a glass “tells us” that its function is to contain liquids (and many others things) and tells us that we can hold it by the handle, if there is one. A computer is turned on by pressing the button with an icon universally known and, in any case, it includes a user’s guide.

In the four cases we have seen previously, all the objects convey information. For example, the train tells us which will be the next station in two ways: by announcing it over loudspeakers or through the signs of the train station. Thus, I can know if I must get off the train either by paying attention to the audio message or the visual one.

Instead, the headphones, the socket and the electric vehicle only communicated information through visual channels. In these cases, when for some reason an error occurs or there is interference in the transmission of information (we cannot see) the user doesn’t know how behave.

In design, redundancy consists of conveying the same information using different sensory modalities (sight, sound, touch, smell, taste, hearing and location) to maximize the efficiency of an object or service. Thus, when the user cannot receive or properly understand the information emitted by the object through one channel, they can resort to other modalities.

ipad buttons

Both the home and volume buttons of this iPad can be seen and detected by touch. The former is slightly concave to accommodate the index finger and the latter highlights the ends where +/- are located.

But redundancy in design also can be based on the same sensory modality used in different ways. In fact, this is very common. For example, signs combining icons and text are useful when we want to ensure that people from different cultural backgrounds won’t misunderstand the icons and people who cannot read or don’t speak our language will be able to understand the message by using the icons.


Toilet sign and Shower sign at airport Hamburg.

typeform buttons

Typeform uses buttons that change of color and physical shape to communicate a status change.

Redundancy applied to product and service design, however, differs from other contexts in one important respect. It not only ensures the correct reception of the information, but it also can enrich the user experience. By combining different sensory modalities, redundancy can create multisensory and even immersive (virtual reality) experiences.

On Sunday mornings I like to go out for a walk. In particular, I like to walk down a street where there is a bakery. I love it because long before I see it I can smell their wonderful fresh bread. At the bakery, I stop a few seconds to see the wide variety of bread and admire how it is presented. This bakery uses two sensory channels: smell and sight.

The Three rules to apply redundancy in design

That said, we must be careful how we apply redundancy. More doesn’t mean better. Adding more sensory modalities willy-nilly won’t make our products and services better. Redundancy should be designed following three basic rules:

1. Coherence. The messages conveyed through the different sensory modalities must avoid conflicting messages, being all them perceived by the user as a coherent whole.

A good example of coherence in the use of redundancy is the traffic lights of the following video. They convey the same information (when passersby are allowed to cross the road) three times through two different sensory channels: visually (icon and countdown) and with sound. Paying attention solely to the intensity of the beep, we are not only able to know when we can cross the road but also when we should hurry up.

2. Integration. All sensory impressions should support the concept of the product or service. That is to say, the different sensory messages not only must be coherent among them, but also with the product itself.

Audi and Mercedes’ engineers know the importance of integration. Their technicians have been engineering the sound of the doors as they lock. Both have teams who fine-tune their own signature sound. Mercedes even has designed variations for different cars. The reason is simple. They know that the sound of a slamming door is as iconic as their cars.

3. Balance. The sensory information should be properly presented in quantity and quality. So harmful is the hyper stimulation as a fluctuating stimulation or the absence of it.

We have all experienced at some time bad designed redundancy. A common example is the keyboard click sound on smartphones. I ignore its utility, but I suppose that designers wanted to reproduce the natural click sound on PC keyboards. However, the artificial click on smartphones is unnecessary and really annoying. This is the reason why turning off this feature is the first thing people do when they buy a new phone.