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How do people decide what to buy?

Want to learn the secret to making more sales? Come to our lightning talk on "Messy Middle" and discover how to understand the consumer decision-making process and use that knowledge to your advantage. We'll see you at the Google booth on April 27th at 11:15 AM!


The way people make decisions is messy — and it’s only getting messier. Still, there are a few things we know about purchase behaviour. We know that what happens between trigger and purchase decision-making is not linear. We know there is a complicated web of touchpoints that differs from person to person. What is less clear however, is how shoppers process all of the information and choice they discover along the way. And what is critical, is how that process influences what people ultimately decide to buy.

As the internet has grown, it has transformed from a tool for comparing prices to a tool for comparing, well, everything. That’s clear in how we’ve seen purchase behaviour change over the years on Google Search. Take the terms “cheap” and “best.” Worldwide, search interest for “best” has far outpaced search interest for “cheap.” Those same dynamics hold true in countries around the world, like Germany, India, and Italy, for instance, when “cheap” and “best” are translated into local languages.






The precise value of “cheap” may vary between individuals, but it still carries a singular meaning. “Best,” on the other hand, can have a wide range of meanings, including value, quality, performance, or popularity.

This is the kind of research behaviour that happens in the “messy middle” between trigger and purchase.



Applying behavioural sciences principles to the purchase decision process


Consumer insights team at Google set out to update our perspective on consumer decision-making. They conducted literary reviews, shopping observation studies, search trend analyses, and a large-scale experiment. The aim was to understand how consumers make decisions in an online environment of abundant choice and limitless information.



What happens in the messy middle? Two mental modes


Through the research, an updated decision-making model began to take shape. In the center of the model lies the messy middle — a complex space between triggers and purchase, where customers are won and lost.

People look for information about a category’s products and brands, and then weigh all the options. This equates to two different mental modes in the messy middle: exploration, an expansive activity, and evaluation, a reductive activity. Whatever a person is doing, across a huge array of online sources, such as search engines, social media, aggregators, and review websites, can be classified into one of these two mental modes.







People loop through these twin modes of exploration and evaluation, repeating the cycle as many times as they need to make a purchase decision.

Cognitive biases that influence purchase behaviour and decision-making


As people explore and evaluate in the messy middle, cognitive biases shape their shopping behaviour and influence why they choose one product over another. While many hundreds of these biases exist, six were prioritized:



These biases formed the basis for the large-scale shopping experiment with real in-market shoppers simulating 310,000 purchase scenarios across financial services, consumer packaged goods, retail, travel, and utilities.

In the experiment, shoppers were asked to pick their first and second favourite brands within a category, and then a range of biases were applied to see if people would switch their preference from one brand to another. To test an extreme scenario, the experiments also included a fictional brand in each category, to which shoppers had zero prior exposure.

If you want to learn how the experiment went and how you can put the theory about "Messy Middle" into practice, come to the lightning talk at Google booth on April 27th at 11:15 AM!


This article was adapted from the ‘Think with Google’ article. You can find the full version here.

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