How graphics increase recall of a web page

Imagine there was a computer virus that secretly deleted all images from websites. You wake up one morning and, bam, your favorite website is all text. The content is still there but all the images are gone.
Probably most people would tolerate this situation for a few days, maybe a few weeks. But after that they would probably stop looking at webpages. Apart from some hardcore geeks they would abandon websites for other forms of entertainment.

Images are essential in communication

Images are not only important but essential in every kind of communication, including websites. That's because we are foremost a visual species. The part of our brains devoted to acquiring and processing images is larger then the area that processes other senses. Images are simply essential to our survival.

But what do I mean by images?

Images can be photos, diagrams, cartoons and any other element that is not plain text. I will refer to this diverse collection of images as "graphics".
Graphics are important in a web page because they increase recall. Many studies have demonstrated that people remember a web page better when it has images associated with text.

In this article I will discuss three attributes of images used on web pages:
- Position
- Captions
- Content

Where should graphics be positioned in a web page?

Graphics in a web page should be positioned near the text they refer to. That's because of one rule of design called rule of proximity.
The rule of proximity states that objects that are located close to each other are perceived as one single element while objects that are far from each other are perceived as unconnected, separate elements. What does this mean?

Let's look at a book. You will notice that paragraphs are separated by one or more blank line. But if the paragraph has a header, the header is positioned immediately before the start of the paragraph it refers to, with no blank line between the header and the text. This makes the header visually part of the subsequent paragraph.

The same is true for all the elements on a page. Elements that are close together belong together.
For that reason, images should always be positioned close to the text they refer to.
There's another attribute of graphics that is often forgotten but should always be present. It's the caption.

Why should graphics always have a caption?

All graphics that appear on a web page should have a caption associated with them.
The reason is that images and text together are recalled more easily than either images or text alone. By positioning a caption close to the image you will make that image more powerful and less forgettable. But how should you structure the caption?

Text in the caption should be made visually different from the main text used on the page. That's because captions belong to the image and should not be confused with the main text. By using a different font you will reinforce the difference and make the caption more closely related to the image it refers to.
Captions are a second level kind of information and should have less emphasis then the main text. Therefore they should be set in a smaller font. You can differentiate them even more if you italicize them.
But how can we make graphics even more powerful? By paying attention to image content.

What content should the graphics have?

When you surf the web you will notice that many graphics are placed in web pages for no apparent reason. Most websites use them to fill blank space or as decorative elements. It's a pity because graphics can be used powerfully to reinforce the overall message of the website.

The way graphics reinforce the message is by having content related to the text they refer to.
For example, if in a passage you are talking about an office chair, the image associated with that text should be an office chair. A regular chair won't be so powerful because it will be perceived as less associated with the text.
By using an image that has pertinent content you will reinforce the message because you will have stated your case twice: the first time with text, the second time with graphics. You will have forced your audience to look at a topic from at least two different angles, therefore making the message more effective through repetition.

But, aren't graphics slow to download?

This proposition was valid a few years ago, since most people didn't have a fast connection to the internet. These days, it's very common to have fast connections and fast computers, so graphics are not really a drag on the page anymore.
But of course it's still important that graphics be optimized for the web. When you choose a graphic to be included into a web page, make sure that the resolution is adjusted for the web and the graphics format is appropriate.

In summary

Graphics are essential in a web page if you want to increase recall of the information offered.
Graphics should be positioned near the text they refer to, they should always have a caption and their content should be consistent with and reinforce the overall message of the page.

Don't worry, there's no computer virus that deletes images from websites. But if one was discovered I am pretty sure it would be quickly deactivated. Images are too important for us as a species to suddenly disappear forever.