In the realm of interaction design, there are 2 main sciences that have a closer relationship to this field than the usually perceived graphic design, and they are - psychology and architecture.

Initially, for most people, it is quite difficult to distinguish between true interaction design and graphic design. And one of the reasons this happens is because the aesthetics of a product is one of the core features that contributes to its perceived usability.

This post is however not my attempt to clarify how interaction design is different from graphic design. Instead, I want to focus on one of the more universal laws of psychology - Getstalt laws - and how they manifest themselves in the way we interact with the products that we build and use.

Gestalt psychology was introduced in 1890, long before we had computer based interfaces. And this makes it even much more relevant in today's day and age because we should never forget that human beings evolved without being surrounded by computers. Our capacity to perceive things has been shaped more by the real and tangible aspects of this world than by the virtual applications that are so commonplace these days.

Gestalt systems deal with four fundamental principles

  • Emergence
  • Reification
  • Multistability
  • Invariance

Emergence

Emergence describes our ability to see things as a whole instead of parts. For example, when you see a car, your mind does not first see the wheels or the windows or the steering and then piece them together to conclude that the object that you are looking at is a car. What you do instead is see the whole object and instinctively compare it with the objects that you have seen before and then the perception of a car emerges out of it.

How does it relate to interaction design?

Since our mind is so efficient and comparing new experiences with past experiences, this is exactly the reason why having a consistent design and interaction language goes a long way. This principle also goes in hand with the notion of - recognition rather than recall. When things are consistent, people can quickly deduce the actions that they can perform when they encounter a new interface on an existing product. By having a design language, even if you break consistency with products of your competitors, as long as you are consistent with your own product, the perceived usability of your product will be higher due to the mere fact that you existing users would be able to repeatedly perform the right task the moment they learn how to do it once.


Reification

This is our ability to construct missing pieces of information from parts.

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Coming back to our car example, notice how your brain does not require all the pieces of the car to be present for you to understand that what you are seeing is actually a car. For example, even if you see a car that has a missing wheel or a steering or any other critical component, you will still recognize it as a car. Your brain is able to successfully fill in the missing information and help you make sense of what you are looking at.

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How does it relate to interaction design?

Ever heard of the saying - 'less is more'? Well this is the epitome of that saying. Although this saying applies to several other concepts and not just visual perception. Imagine how you could exploit our innate ability to see things that don’t really exit on screen, design the minimal and let your users fill in the gaps. Not only can it help you from avoiding clutter, it can also turn into an opportunity to delight your users.

Just to elaborate on the saying - ‘less is more’, this is mainly to encourage the ‘removal’ of features and interactions that are redundant for performing a given activity. Many products suffer from a disease called ‘featuritis’. Although having a large set of features is a good thing, having all of them get in each other’s way when a user is trying to interact with one of them is not really a good idea.


Multistability

This is probably one of those principles that you want to keep in mind because you want to avoid such a thing to happen in your design. Multistability is our ability to simultaneously form multiple perceptions for the same visual stimuli.

The most common example of this is the Necker’s cube.

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How does it relate to interaction design?

One has to be very careful about multistability because often the designer himself might not be aware of the multistable nature of the design since (s)he is accustomed to see only one stable perception of the visual stimuli. A great, or should I say bad, example of the manifestation of multistability can be found in the below banner advertisement. You can also read fastcompany's article about it.

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The designer probably did not pay proper attention to kerning (the spacing between the characters) which led to an ambiguous representation of the word ‘click’. In this example, the word click exhibits multistability when observed from a slightly different viewing angle.


Invariance

This is our ability to recognize objects even if they have been distorted. The best example of its usage in real life is in animation where human beings and animals have exaggerated features yet we are able to identify them as their real life counterparts.

How does it relate to interaction design?*

A large aspect of interaction design revolves around attention management. Good interactions help people complete their task smoothly with minimal interruption of a user’s attention. However in order to perform a task, one has to also design visual elements that appropriately attract the user’s attention. One mostly achieves this through icons and images. But the mere fact that an item in the real world can be represented by multiple icons, even though they might be a slightly distorted or exaggerated form of the real thing is living proof of this principle in daily web browsing.

A simple google search for the keywords phonebook icons shows you several icons of the concept of a phone book. They are all different from one another, however users are easily able to associate them with the original concept irrespective of which icon they come across.

As an interaction designer, you will occasionally want to evaluate your designs and interactions with these psychological principles. It may either open a window of opportunity in your designs or save you a tonne of embarrassment, the former being more likely than the latter.