4 psychological principles to make products and services more human
Designing products and services for the human brain
Huge thanks to Diogo Gonçalves at Nudge Portugal for collaborating on this article.
I’ve seen a lot of clients who have brought in (very) expensive technology, only to find 12 months in that they are using a fraction of the features they’re paying for. I have countless others who have come to us, totally confused as to why their customers aren’t making the full use of the products and services they’ve painstakingly designed. It made me wonder, what lessons can we draw on from psychology to help people build more intuitive product and service experiences?
Might the key to driving adoption of innovative new technologies lie hidden in plain sight, in a pair of scissors?
Let’s start with the humble scissors.
Ah, the scissors, a masterpiece of design. Immediately after you look at them you know that the number of possible actions is limited.
- We know we can put something into the holes, and the only logical thing that will fit are fingers. The holes are affordances: they allow the fingers to be inserted.
- The size of the holes provides constraints to limit the number of fingers: the big hole suggests several fingers, the small hole only one.
- The mapping between holes and their movements is clear and originates an immediate understanding, easily learned and always remembered.
- Finally the sum of our experiences alerts us to the convention that to cut through something thick, we need to apply just a little more pressure to force the blades together.
And snip. That’s it.
A scissor is an example of good design and usability: it’s visible structure provides clear clues to how it works, through its affordances, constraints, mappings and conventions . Unfortunately, the world is full of poorly designed objects that cannot be understood, and interfaces that lead to error.
In what follows, we will describe how having in mind the behavioral principles of affordance, constraint, mapping and convention, can help us to shape products and services that feel intuitively more human.
1. Affordances — The Psychology of Materials
In 1959, Harry Harlow began a series of heart-wrenching experiments that mapped the impact of separating infants from their mothers (using Rhesus Monkeys).
Get the tissues out, this ain’t pretty.
Harlow separated infant monkeys from their mothers a few hours after birth, then arranged for the young animals to be “raised” by two kinds of surrogate machines, both equipped to dispense milk. One mother was made out of bare wire mesh. The other was a wire mother covered with soft terry cloth. He found that monkeys who had a choice of ‘mothers’ spent far more time clinging to the terry cloth surrogates, even when their physical nourishment came from bottles mounted on the bare wire mothers.
Although it’s a little hard to stomach (those poor little monkeys right?) their suffering wasn’t in vein. Harlow’s work provided some of the first experimental evidence for prioritizing psychological over biological parenthood, creating a cultural reassurance that love really is all you need when it comes to parenting.
No one wants to cuddle a cage.
Quite by accident these experiments also provided evidence about the Psychology of Materials, and the affordances of two types of materials as different as terry cloth and bare wire. Bare wire mothers cannot afford to fulfill emotional and psychological nourishment — let’s face it, no one wants to cuddle a cage.
So what do we mean by “Affordance”?
A chair affords (i.e., is for) support and, therefore, affords sitting. An umbrella affords us to stay dry, a pen to write letters and draw pictures. Paper is for writing on. Glass is for seeing through. Rubber is for stretching. Buttons are for pushing. Knobs are for turning. Slots are for inserting things into. Affordances provide strong clues for the operation of things.
When affordances are used properly, the user knows what to do just by looking: no picture, label, or instruction is required.
2. Constraints — Knowledge in the world
We’ve all had the “was-that-a-glitch-in-the-matrix” experience of trying to insert a USB pen drive, getting it the wrong way round, flipping it (still wrong) then flipping back again only to find what feels like the original configuration now works. A phenomenon the Reddit community have dubbed “Schrodinger’s USB Port”.
This happens because there are no visible cues on the device (i.e., there is no knowledge in the world), and most of the times there is no knowledge in the head of the person using it (which side is up anyway?).
It’s no wonder that Apple led the abandoned of this format in favour of an ‘any way works’ approach, to remove those daily moments of frustration where you invariably get it the wrong way round (multiple times).
What do we mean by “Constraint”?
Knowledge for using products and services can be distributed, partly in the head, partly in the world (visual, auditory, tactile), and partly in the constraints of the world. Let’s take the example of designing a motorbike.
- Physical constraints define ‘allowed behavior’, because the physical properties of objects constrain possible operations: the way things can or can’t move, transform or combine. A forward facing seat means the rider can face only one way comfortably.
- Semantic constraints rely upon the meaning of the situation to control the set of possible actions. For a motorcycle, there is only one meaningful location for the handlebars, in front of them in the direction they wish to travel
- Cultural constraints determine for example determine that red stop lights should be placed at the rear of the bike rather than green ones
- Logical constraints dictated, in the case of the motorcycle, that with two tyres to fit, if one is already in place at the front of the vehicle, the other must then go in the mirrored location at the rear
Failed constraints: The 2000 US Presidential Election
The year is 2000 and Al Gore and George Bush are head to head with everything coming down to a key swing state, Florida.
In the US voting is done by physical cards and voters are required to ‘punch’ a hole in their card to represent their vote. In this particular state, there were not sufficient physical constraints to deliver the ‘clear outcome’ objective of the voting process. Let’s take a look.
While the vote for Bush was clear, many voters believed that the second hole would be for for Al Gore, when in fact the second hole was actually for Pat Buchanan.
What complicated this further was a second constraint failure. Citizens are required to punch through the card, completely removing the ‘chad’ (the bit of paper that falls out). But what happens if someone partially punches through? If just the corner is attached, does this count? Is this a mistake or is this a vote?
In the end these outliers have to be judged manually, by humans, who take a view on the intention of the voter. In Florida, Bush won by a margin of just 537 votes, and the rest is history.
Successful constraints: The Anti-Bench
A great example of intentional physical constraint is the famous Camden Bench, known as a masterpiece of ‘unpleasant design’.
This bench was designed by Camden Council, in London, specifically to prevent a smorgasbord of anti-social behaviours. There is no space underneath to place a bag, removing the possibility of thieves sneaking up to steal them from behind. The angles along the top of the bench make it impossible for a skatboarder to slide across it’s edges. There isn’t sufficient space to lie on because of its undulating shape, removing the possibility of homeless people using it as a bed for the night. Finally, it’s waterproof/anti-paint surface makes graffiti an impossibility.
When constraints are used to proper effect, the user is funnelled towards a set of interactions to arrive at a desired outcome
3. Mappings — the relationship between controls and results
A natural mapping takes advantage of the spatial of functional layout of components and the things they affect or are affected by. If two switches control two lights, the left switch should work the left light, the right switch the right lights. If the lights are mounted one way and the switches another, the natural mapping is destroyed.
So what do we mean by “Mappings”?
Some natural mappings can be cultural and biological, as the universal standard that a rising level represents more, a diminishing level, less. Other natural mappings can follow from the principles of perception and allow for the natural grouping or patterning of controls and feedback (see below).
Natural mappings have the power to reduce the need for information in memory. Consider the experience of using someone else’s laptop and finding that when you scroll down, the document scrolls up instead. Technology brands go to great lengths to build natural mappings into their products for exactly this reason — we swipe up to bring up a control panel, we slide down to turn down the volume, we swipe across to move through our photos.
When mappings are used to proper effect, the persons’ working memory experiences less ‘load’ because the layout, orientation or interaction ‘store’ some of that information
4. Conventions — The learned expectations between interactions and outcomes
A convention draws on the learned expectations a user has over the history of their interactions with an object, or interface, to create predictable outcomes.
Interaction Conventions.
Let’s take music interfaces. Conventions for music controls were culturally established in the 1960s, with Grundig’s 1961 cassette tape player.
We know the forward facing arrowhead instructs us to ‘press play’, our two vertical lines let us pause and our square helps us ‘stop’. When we press play on our iPhones we’re interacting with a design convention that is almost 60 years old.
Category Conventions
These conventions can be for interfaces, or they can be developed at a category level. Take the example of a travel website. We have expectations about it’s format, content and functionality — there is a shared visual language that makes these sites feel familiar and gives us confidence to interact when we encounter a new one.
An ‘innovator’ may want to create something totally new, but the risk is we introduce a learning curve that may that may cause them to abandon the site, and therefore losing the sale.
The increasing pace of change creates a challenge for an evolving mental lexicon of design conventions as new interactions take their place in our lives. How do we innovate and introduce new product and service experiences and yet remain familiar?
Take voice and natural language interaction and the trend towards a conversational or ‘no interface’ default with technology.
Google report that 10% of all searches are conducted by voice and expect this to grow to circa. 40–50% by 2020.
With the introduction of Siri, Amazon’s Alexa and Google Home to name a few, we are in the process of creating new cultural design conventions around voice interaction. We will come to expect to be able to command our technology to create outcomes, much in the same way we have a learned interaction/outcome when we communicate with people.
Conclusions — User-Centered Design
Using these behavioral principles will allow companies to design for usability and understanding, and make the experience of their products feel more familiar and human-like. The main principles to achieve a good user-centered design are:
- Use constraints to make it easy to determine what actions are possible at any moment
- Make things visible, including the conceptual model of the system, the alternative actions, and the results of the actions
- Make it easy to evaluate the current state of the system
- Follow natural mappings between intentions and the required actions, between actions and the resulting effect, and between the information that is visible and the interpretation of the system state
- Lean on conventions to help people apply their knowledge from other products to quickly make sense of the interactions you want them to take with yours.
