several portraits on top of white textile




Let’s return to Jim, who was looking into buying a new car. He’s debating whether to get a small budget sedan or a larger sport utility vehicle with lots of bells and whistles. Psychologists have had two competing theories—the prototype theory and the exemplar theory—about how people think about decisions like these.

The prototype theory states that people have memories of different experiences, and that they create a general overview of those memories for a specific category. For example, if Jim thinks about deciding to buy the small sedan, he’ll make that decision based on a general category overview of “small sedan.”

The exemplar theory starts with the same idea—people have memories of different experiences—but it states that decisions are based not on a conglomerate overview category of memories, but on one or two specific memories. For example, if Jim thinks about deciding to buy the small sedan, he’ll make that decision based on his memory of the road trip he took with his friend Linda in her small sedan and his mom’s small sedan from when he was in high school.

The competing prototype and exemplar theories have been around for over 30 years. It was very difficult to devise an experiment to figure out which model was true until fMRI brain scanning became available. Michael Mack (2013) used fMRI brain scanning to test the two theories.

If the prototype theory is true, then the fMRI imaging would show activity patterns in some parts of the brain. If the exemplar theory is true, then the activity should show in different areas.

And The Answer Is…

A majority of the participants in the study showed brain patterns during decision tasks that matched the pattern you would expect if people were making decisions based on the exemplar model. (For any of you who get into the details of brain science, Mack found that the posterior parietal cortex was the critical brain area for these memory/decision tasks.

His theory is that the parietal cortex plays a critical role in encoding and retrieving exemplar memories for decisions.)

What does this mean for design? When people are making a decision, they’re using specific memories to think about their decision. They’re basing their decision not on generalities, but on specifics. If you know about their specific memories, you’ll be better able to predict and even influence their decision.

For example, if you know that the only sedan your potential customer owned in the past was a gray Honda Accord, then you can assume that when he thinks about a sedan he’s thinking about that gray Honda Accord. If he liked the gray Honda Accord, then you can talk to him about the new Honda Accords, or show him cars that are like them. You could show him photos of the new gray Honda Accord. If you know that he didn’t like the gray Honda Accord, and that he went on a fishing trip he really enjoyed with his friend in his friend’s blue sport utility vehicle, then you can show him photos of a blue sport utility vehicle. His decision will be influenced by these specific memories.

You might be thinking: “Wait, I’m designing a website. I don’t know what every visitor’s memories of cars are. How can I possibly build that into the website”?

I admit that this takes a different way of thinking about design, and it requires some interesting changes. But imagine for a moment you’ve designed an interactive experience where a person comes to your car-buying website and is prompted to create a “past car parade.” You ask him to talk about his first car. (Or if you don’t want to go as futuristic as talking about his first car, then you can ask him questions that he answers just by choosing fields on the screen). Based on his answers, you bring up a picture of that car. You can also find out if he liked the car, and if he has good or bad memories of it. Then you go to the next car he owned or drove or spent time in. You keep going until there is a picture on his screen of all the cars he has had “relationships” with and liked.

If your customer is young and hasn’t previously owned a car, then the car parade could include cars in which he had adventures, perhaps a parent’s car or a friend’s car.

Next, you could take him through a series of choices about the next car adventure he wants. You can start with photos from the car parade and, based on these photos and questions, you can predict, show, and help him refine the car he wants.

By doing this you’re triggering specific memories and using those memories to guide him to a decision.


  • In your design flow, ask people about specific memories and experiences with products or services in the past that match the products or services they’re deciding on.
  • Provide a summary of these experiences to trigger specific memories while they’re making a decision.


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