The psychology of persuasive product design

Here are my notes from an interesting conference talk that I heard by the psychologist Nathalie Nahai and some points from Nir Eyal’s book Hooked. The notes refer to common psychology principles used in some digital products.

Whenever you work with these principles it’s important to understand that there is a fine line between facilitation, helping people achieve their goals, and coercion and manipulation. Where we sit on that line is usually to do with our intent. As designers of products and services it’s important to understand that we are the architects of a future that we want to live in.

Endowed Progress

Here’s an interesting case study. Psychologists gave people at a car wash a loyalty card, get the whole card stamped and you get a free car wash. One group was given a loyalty card with 8 circles in it, the other with 10 but 2 had already been pre-stamped. Which group had the higher redemption rate? The second group had twice the redemption rate. Even though there were the same amount of steps required by both to get a free car wash the second group saw it as a process that’s already started but incomplete. Companies take advantage of this online by firing up popups that already have a 50% incomplete progress bar on there. Even LinkedIn had a progress bar saying your profile is x% incomplete.

So how does this work? It appears that people who have been given a small artificial advancement towards a goal are much more likely to work harder than those that have not been. We’re naturally more motivated to complete tasks that we have already started, whether you give yourself the start or someone else gives it to you. It’s not just about a little push at the beginning, proximity is also important. So the closer we get to a goal the more likely we’ll put in the extra effort to complete it. This concept can be easy to build into products, so giving out a simple card with 2 holes punched in it was enough to give people that initial push and to create the proximity effect.

Daniel Kahneman’s prospect theory says that losses loom larger than gains. We have all probably experienced this before on eBay where we pay over the odds for something just because we’re about to lose an auction. Especially if we’ve have already pictured ourselves with the item and feel like it’s owner before we even get it

Sunk Cost Fallacy

Players are much more likely to return to a game like Farmville when they feel like they have something to take care of. A rational person would ignore the sunk cost (i.e. The time, effort and money) and as soon as the novelty is over they might think I’m not going to waste anymore time on this. But it appears in reality it’s very hard to walk away from a sunk cost. In video games, players are very reluctant to discontinue something that they have put effort into, because the sunk cost of having planted all the tomatoes in Farmville makes you want to come back (there’s other factors at play also like social dynamics because your friends are doing it too so there’s a reinforcement from them)

Appointment Dynamic

An appointment dynamic is where companies say to people you’re a player and your participating in our product so we’re going to give you a reward to keep you coming back. So customers come back for more, creating habitual patterns of use. The simplest example of this is when you get up each morning and you look at your phone to see those red symbols and notifications on the app icons.

So how do some of these principles work together? Endowed progress at the beginning gives your customers an artificial push. Once you’ve done that and they keep using the product, the consistency principle kicks in and they’re much more likely to complete said goal. By then they have already spent some time on it, so that creates a sunk cost and encourages further investment. At the end you give them a reason to come back so the appointment dynamic kicks in and this is how you create habitual cycles. If you want to use this model the first thing you have to do is research what motivates your users. Once you know what motivates them give them some of it for free and then map out the user journey so you can see where to introduce the appointment dynamic.

Opportunity Cost

This refers to the benefits that you have forgone through a particular use of resources. There are 3 main costs when It comes to digital products:

  • Attention
  • Time
  • Money

The best way to get a customer’s attention is through an emotional response, this is why apps like tinder work so well. The other way to grab attention is through social reinforcement, we all want to be liked and valued. This is why a Facebook like, a retweet or a favourite work so well in digital products. The other way is to give people small rewards (especially if they don’t know when they are going to get them, or how big they are going to be) their dopamine levels will spike and they’re more likely to continue hunting for that kick, so it creates a habit loop and we keep going until we get that dopamine kick. In his book Hooked, Nir Eyal says this is why we like to scroll down a page of tweets, the unexpected element of what we might find gives us small dopamine kicks.

The other cost is that of time. One of the main reason why people use certain apps is because they are bored or alone. You can minimise time costs by understanding the customers incentive for using the product and also by understand their usage patterns through analytics. King understood how people using the tube or metro have 15–20 mins to kill and developed Candy Crush around that user journey.

The third cost is the cost of money. Research has found something as simple as removing the pound sign from the cost of a product makes people more likely to part with their cash. Some companies make you wait longer for a product e.g you might have to wait longer to download something, or games like Clash of Clans make you wait longer to build a certain wall, and then they give you the option to buy yourself out of that pain. Research has found adding an intermediary currency between the customer and real money reduces our ability to asses the value of a transaction, the game Sim City for instance lets you buy gems, and you spend the gems in the game losing touch with how much they originally cost. So to reduce the cost of money companies create a fun pain, making people wait, and use something like an intermediary currency allowing them buy their way out of that pain.

Hedonic Adaptation

Say you have two groups, you give the first group a massage for 160 seconds. You give the second group an 80 seconds message, then a break, and then the message for another 80 seconds. Which group will report a higher satisfaction rate and will be willing to pay more for the product? It’s group B — because they experience a loss. They get the massage, then in the break they feel I was really enjoying that, and then when they get it again feel the high, and research shows it’s even better than before the break. This is also the same with unpleasant experiences. So if someone is hoovering and the noise is loud, and they stop and come back it feels even worse. Or if there’s a bad smell in the room and you leave the come back it seems to smell worse. You see this with games like Angry Birds, where they release a game and the excitement is awesome and then it fades and you lose interest. So what they do is release a new one, and they try to keep you in this constant excited state. You’re continuously engaged and they are hacking your hedonic adaptation response.

How does hedonic adaptation work? People become accustomed to a positive or negative stimulus and the response is attenuated over time, so basically you become desensitised. But there are several mental hacks you can use to reduce the drop off:

  • Updating products so that you create a feeling of novelty, but not so much that you increase the customer’s cognitive load.
  • Changing the layout or structure slightly. But not dramatically overnight and risk people hating it (eBay took 40 days to change their background colour from yellow to gradually white but because it took that long no one noticed it and got upset)
  • Alter the user experience: one of the best methods is to make the rewards unpredictable.

Key takeaways from the talk:

  1. If you want to build successful products you have to understand what are the key psychological pressures for your users or customers.
  2. Endowed progress — so giving people a slight artificial boost towards a goal makes people want to continue and feel like they want to put in that extra effort towards that goal.
  3. Sunk cost fallacy — people are unwilling to abandon something that they have already invested in.
  4. Appointment dynamic — if you’ve got them in that consistent use, give them a time for which you will reward them for using your product
  5. Opportunity cost — make sure that you are reducing the perceived cost of time, attention and money.
  6. Hedonic adaptation — try and find ways to hack the natural hedonic adaption.