The psychology of design: human memory

What is user experience design psychology?

‘User experience design psychology’ or ‘UX design psychology’ for short, is the study of how a user interacts with a product. UX design psychology considers the nature of the target end user: who they are, how they behave, and even how they think. At least, that is the ‘user experience’ and ‘psychology’ part: the ‘design’ part of ‘UX design psychology’ is how engineers and manufacturers act on the nature of the end user. In particular, it is the question of how such designers may implement hardware and/or software that accommodates the psychology of the target end user.

In this article, such a ‘target end user’ will mean the intended consumer of a manufacturer’s electronic devices (namely smartphones). Because while UX design psychology can also refer to companies’ websites, branding, and so on, this piece aims to consider human psychology in the context of consumer electronics. With that said, the next section covers one of the many core areas of human psychology that designers must act on in their production of consumer products: memory.

Memory

The target end user’s memory, particularly their short-term and long-term memory, is a vital consideration in both the hardware and software design of smartphones.

At its earliest stage, human memory is one’s initial experience of a stimulus or stimuli, through any combination of these senses: sight, hearing, and touch (plus – although they are less relevant to consumer electronics and UX design psychology – taste and smell). Such a list of senses is why the very first stage of memory is called ‘sensory memory’.

Sensory memory in smartphone hardware

In terms of hardware, designers are increasingly acting on the importance of sensory memory: they have a clear interest in appealing to the target end user’s sense of touch by not only using physical buttons on the side of their phones, but also introducing haptic feedback on their touchscreens to mimic such an experience of pressing physical buttons.

A crucial appeal to sensory memory can be seen in Apple’s use of vibrations whenever the user opens their Apple Wallet app. Namely, the motors in the newer models of iPhones generate a small but unmistakable series of vibrations – which form the response known as haptic feedback – to help notify the user that the phone is ready to carry out a contactless payment. Haptic feedback is best used to reinforce sensory memory when it is always associated with the stimulus, as Apple itself explains on its developer.apple.com page. “Use haptics consistently,” Apple advises designers and other developers. “It’s important to build a clear, causal relationship between each haptic and the action that causes it so people learn to associate certain haptic patterns with certain experiences.”

Apple goes on to explain that haptic feedback’s combination of visual, auditory, and tactile interfaces are the difference between the end user's clear memory of (and therefore ability to navigate) the smartphone's on-screen information – and outright confusion. After all, consider how dispiriting it may feel if you only receive that reassuring vibration every so often. In such instances, the target end user may feel that part of the hardware or software has failed. Altogether, the use of haptic feedback reflects the importance of using a consistent stimulus to appeal to sensory memory (and ultimately short-term and long-term memory) in UX design psychology.

(More information on the human desire for a cause-and-effect relationship between associated stimuli and memory formation can be found by looking up ‘Pavlovian Conditioning’.)

Short-term memory in smartphone software

With the link between tactile user experiences and sensory memory now considered at the hardware level, let’s move on to another form of memory, namely short-term memory, in terms of smartphone software. In particular, the focus will now be on the core user interface of a phone: the app menu (an example of which is pasted below).

As the above photo of an iPhone shows, there are only a handful of apps on-screen, and the most important apps – just four of them – are in a dedicated, highlighted spot at the bottom of the smartphone monitor. This is known as the ‘app dock’ and a zoomed-in photograph of it is below.

These four apps form arguably the most crucial software on a smartphone: left to right, they are the call, text messaging, photo album, and camera apps. But why are those apps right at the bottom of the screen and each limited to being one of four assigned slots?

The answer is that short-term memory in humans is very limited. One of the most well-known theories of memory refers to the fact that humans’ short-term memories can only hold around five to nine items in a list. And in fact, as a National Library of Medicine paper explains, such memory capacity is often even fewer than five. The study, entitled ‘The Magical Mystery Four: How is Working Memory Capacity Limited, and Why?’, refers to short-term memory as "a central memory store limited to three to five meaningful items".

It is unsurprising, then, that iPhones have been designed with just four assigned slots in the app dock: five or more slots would be less palatable because humans prefer to have a small number of easily-recognisable, core options at their fingertips. Put simply, the best UX designs appeal to the phrase, ‘less is more’. And this consideration of limiting the number of buttons in a user interface is just one example of a subset of UX design: information architecture.

Appealing to short-term memory with information architecture

Information architecture (IA) is a core principle of both user experience and user interface design: it is the science of organising digital content that is as human-readable as possible. As such, it is often used to relate to how websites are designed; but again, it is just as relevant to the operating systems of smartphones.

In the case of smartphones (as well as other smart consumer electronics, like tablets), information architecture draws on the question of how the target end user’s apps, widgets, and other inputs, may be designed in a way that is as accessible and memorable to them as possible. A good IA designer would probably agree that the best formation of buttons on a smartphone menu is one that is grid-based and able to offer a filing system so that multiple apps may be categorised together. After all, like with so many other aspects in life, our memory of how to navigate various systems requires good organisation: no one wants to trawl through a cluttered user interface, let alone remember how to use it!

Memory in user experiences, interfaces, and information architecture

The need to introduce intuitive hardware, simple interfaces, and a good understanding of information architecture draws on a key part of UX design psychology: memory. By complementing the user experience with a smartphone system defined by tactile input, low-maintenance app menus, and an altogether readable interface, designers may appeal to the sensory, short-term, and long-term memory of their end users.

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