Adding captions to the figures and tables of your documentation provides an excellent opportunity to solidify your point and help readers who are scanning the content to quickly understand the subject matter. In this short article we’ll provide some tips on how to use captions effectively in your documents.
Before we get into the content of a caption, let’s briefly talk about positioning. Generally, figure captions are placed below an image or diagram while table captions are placed above a table. The commonly‑accepted reasoning behind this is based on how the brain tends to process visual information.
It’s believed that tables are considered to be part of the “text”, and thus the brain tends to interpret them in the same way as a paragraph (left to right, top to bottom). Thus, it only makes sense that a table caption is best placed before the “text” that it introduces, in this case, text contained in a table. Images and diagrams on the other hand, are usually interpreted by the brain before text, so placement of the figure caption will be interpreted after the brain has processed the figure.
Now that we understand the psychology, let’s talk about the look (i.e. the font/style). Captions are most effective when they’re visually different from the body text. In most documentation, figure captions use a smaller font size and different style than the body text to help offset them. Thus using a font size a few points smaller than the body text and introducing a style like italics, makes for a good visual presentation of captions.
If you’re using MS Word, be sure to use the Insert Caption feature and specify the caption type (table or figure). This will not only insert the caption text for you, but will also add the “Figure” or “Table” keywords and an auto number which will be updated as new figures and tables are inserted. In addition, the caption will also be added to your document’s table of figure captions/tables if you choose to add one. Optionally, you can also select a figure or table caption style if your document supports it, as this will stylize the caption for you. Note though that this is not something the caption insertion functionality will apply for you, so you’ll need to do it manually each time you add a caption.
When it comes to content (i.e. what to write for the caption), avoid stating the obvious. For example, if the diagram in the figure shows a screenshot of selecting the File/Save as menu, avoid the temptation to create a caption which says “The File->Save As menu”. Instead, stop and think about the significance of what the figure or table is trying to communicate. For the aforementioned example, a better figure caption would be something like “Locating the Save As menu in Product X”, or “Saving a document for the first time using the Save As menu to specify a filename”. Such captions describe an action that the reader is trying to learn about, such as where they can find this menu, or that they must use this menu upon first saving to specify a name.
As both of these examples show, it’s often good to start with a verb which describes the action being communicated, though this is not mandatory. You should however try to be consistent between your captions so that they all read in a similar manner.
Likewise, table captions should also be consistent, though tables tend to summarize facts and other information, rather than show a concept. Therefore table captions tend to read more like “Summary of Data Points”, “Values for use in ….”, or “Inputs for function X”.
So that in a nutshell is how to best use captions. Two final tips I’d like to pass along before signing off are both to do with caption content: the first is that I like to add a “-“ character before my caption text which separates it from the word “Figure” or “Table” (e.g. “Figure 1 – Locating the File Menu”) . This makes the caption easier to read especially in a table of contents where the word “Figure” or “Table” is repeated on many lines. Just be sure to use this consistently and don’t mix em‑dash and en‑dash which is something I see a lot of in technical documentation.
The second tip involves capitalization. I like to capitalize each “major” word in the figure, with words of four characters in length or longer being good candidates. Again, this is not mandatory, but be sure to use this consistently between all captions. These little style elements go a long way to adding a professional touch to your documentation, and help the reader to absorb information.
In short, if you’re not using captions, they can be a great tool to help readers learn information quickly. And if you haven’t looked into using Word’s caption feature, I recommend taking a few minutes out of your day to do so. It’s fairly easy to use and will provide additional benefits such as auto numbering and updating.