It’s still one of the great mysteries of the Internet: with the millions of images that bombard us on the web every day, what makes us click on one instead of another? Are some pictures universally appealing, or is art always a matter of personal opinion?

Netflix has been pondering these profound questions for years. After all, images are critical to getting you to binge: A small, compelling thumbnail could mean the difference between getting you to spend the entire weekend watching House of Cards or losing interest and bouncing over to Hulu.

Recently, Netflix—which is famously tight-lipped about its own data—has been doing experiments to better understand which images capture our attention and why, and shared some of its findings in the below post.

The power of a picture – a lesson from Netflix

Imagine having to tell your friend about the last movie you watched through a single drawing on the back of a playing card. If you had to encapsulate the entire movie into a few inches to convince your friend they’d love the movie, what would it look like?

As detailed by my colleague, Gopal Krishnan, in this technical blog post, we have been working hard the past few years to create a framework that allows us to effectively intersect big data with creative, ultimately helping members discover stories they will enjoy even faster. As a result of that work, we now have the unique ability to understand how to most effectively tell our members why a story is right for them — all through a single image.

Broadly, we know that if you don’t capture a member’s attention within 90 seconds, that member will likely lose interest and move onto another activity. Knowing we have such a short time to capture interest, images become the most efficient and compelling way to help members discover the perfect title as quickly as possible. After all, the human brain can process images in as little as 13 milliseconds.

In early 2014, we conducted some consumer research studies that indicated artwork was not only the biggest influencer to a member’s decision to watch content, but it also constituted over 82% of their focus while browsing Netflix. We also saw that users spent an average of 1.8 seconds considering each title they were presented with while on Netflix. We were surprised by how much impact an image had on a member finding great content, and how little time we had to capture their interest.

Around the same time, we launched a charming original documentary called “The Short Game” and we wanted to do everything possible to help that title find its audience. Gopal goes into more detail here on this title and how we have approached testing imagery. In the end, we saw one clear thing — using better images to represent content significantly increased overall streaming hours and engagement from our members.

Since then, we have built a system that tests a set of images for many titles on our service — helping display a compelling image to drive engagement. In developing this system, we learned many interesting things around imagery and what actually compels a member to watch a title. Here are some of the biggest trends:

Emotions are an efficient way of conveying complex nuances

It’s well known that humans are hardwired to respond to faces — we have seen this to be consistent across all mediums. But it is important to note that faces with complex emotions outperform stoic or benign expressions — seeing a range of emotions actually compels people to watch a story more. This is likely due to the fact that complex emotions convey a wealth of information to members regarding the tone or feel of the content, but it is interesting to see how much members actually respond this way in testing. An example of this is seen in the recent winning image (“winning” means it drove the most engagement) for the second season of Unbreakable Kimmy Schmidt below:

Great stories travel — but regional nuances can be powerful

While we are becoming more connected across cultures, we have seen that regional differences still exist and are important for some titles and imagery. A good example of this is Sense8, a Netflix series in which eight people can telepathically experience each other’s lives. Sense8 has diverse appeal given its many international actors and storylines, and it is a story that resonates with many different types of people. When it came to the artwork for this title, this diversity was reflected in the winning images and how much they varied between different countries and cultures: Examining regional differences helped us see that while great stories transcend borders, it is important to understand how presenting each story in different regions impacts how quickly members from around the world actually discover that story through artwork.

Nice Guys Often Finish Last

Throughout our research, we have seen that using visible, recognizable characters (and especially polarizing ones) results in more engagement. Our members respond to villainous characters surprisingly well in both kids and action genres in particular. For Dragons: Race to the Edge, the two images of villainous characters seen below significantly outperformed all others:

Less is more when it comes to cast size

One of the earliest trends we saw was an image’s tendency to win dramatically dropped when it contained more than 3 people. This directly informed our creative decisions for Orange in the New Black, as is evident when you look at the main creative for each season side by side:

This can feel counter-intuitive, particularly with shows that have an ecliptic mix of talented lead characters. But while ensemble casts are fantastic for a huge billboard on the side of a highway, they are too complex at small sizes and ultimately, not as effective at helping our members decide if the title is right for them on smaller screens.

Season 1

Season 2

Season 3

Imagery is a powerful thing — it has the ability to move people in so many different ways. Over the last few years, we have worked hard to learn how a winning combination of technology and creative helps members discover stories they will enjoy faster and ultimately, have a better Netflix experience. While the results from our research were often surprising, it is clear that an image can move people in powerful ways and done right, pictures can help people find the stories that they will love even faster.

As posted on Netflix. Written by Nick Nelson.