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Let’s say you’re the designer for an online grocery store. You’re designing the product pages for a website or phone app. The people who will be using these product pages shop at the online store regularly. They’re familiar with the products, and they have preferences for particular products and particular brands.

There could be a lot of questions about how preferences might influence decisions, for example:

  • Are preferences more of an influence than the visual design of the page?
  • Is there anything you could do to make them choose one product over another?
  • If you show pictures of the packaging (for example, a picture of the box of crackers), could the manufacturer do anything to increase the likelihood that someone would pick their product over another brand?
  • Which is strongest: the individual’s previous brand preference or something about the page or package design?
  • Can you override an established preference based on visual design?
  • We explore some of these questions below.

Exogenous Vs. Endogenous Influencers

Influences that are outside of people are called “exogenous (external) influencers”; influences from their preferences are called “endogenous (internal) influencers.”

The “How People See” chapter described research showing that people use visual complexity and color when they are evaluating visual appeal, and that they make those judgments in less than one-half of a second (500 ms). But what happens when they’re choosing from several products?

Milica Milosavljevic (2011 and 2012) searched for the answers to these questions in a series of studies. She had people rate their preferences for different snack food products, and then showed the products to them quickly on a screen. The participants had to decide which product they wanted to purchase.

Here’s what Milosavljevic discovered:

  • The visual brightness of the product packaging (called visual saliency in the research) was more important in the choice than the participants’ preferences.
  • If Milosavljevic slowed down the responses, either by asking participants to be confident before choosing, or having them choose with their hands rather than their eye gaze, then the visual saliency effect—choosing based on the brightness of the product package—was even greater.

So the endogenous factor of product preference can actually be overridden by an exogenous factor of making one product appear brighter than others on the screen.

The manufacturer could create a brighter package that would then translate into the image at the website. Or the designer could influence choice by making the product image brighter, or using additional visual attributes (boxes, borders, highlighting) to increase the visual saliency of a particular product.

The minimal time to make a product decision is around 313 ms. That’s one-third of a second—even faster than the time to decide if a website is visually appealing.


  • When you want people to choose among different products or alternatives, make the product you want them to choose more “visually salient” than the others.
  • Use the visual salience/brightness technique when you want to overcome the target audience’s previous preference.
  • Use the visual salience/brightness technique when you want your target audience to choose a product that is unfamiliar to them.


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