Traditional writing guidelines are clear on the use of passive voice:
Worst: The passive voice should be avoided.
Bad: The passive voice should be avoided by writers.
Better: Writers should avoid using passive voice.
Best: Writers should use active voice.
When structuring a sentence, active voice ("Actor does X to Object") is usually better than passive voice ("Object has X done to it by Actor") because it more directly represents the action. As a result, readers don't have to jump through as many cognitive hoops when trying to understand what's going on.
For the same reason, it's usually better to write a positive statement ("do X") than a negative statement ("avoid Y") , and it's almost always horrible to use double negatives ("avoid not doing X" ). Again, the simpler the translation between the text and the user's mental model, the easier the writing is to understand.
Typically, it's even harder for readers to understand passive sentences that don't explicitly state the actor. This style can also lead to additional usability problems if users misinterpret who's doing the action. For example, if you write "Social security taxes must be paid monthly" readers might think that employees have to pay the tax. In contrast, "Employers must pay social security taxes monthly" is clear and easy to read.
Usability increases when users need fewer mental transformations to convert a sentence into actionable understanding.
Writing style impacts website profitability: the easier the writing is to understand, the more likely customers are to plow through your words. Users don't like doing hard work. That is, users prefer effortless reading (to state it positively, and thus improve readability).
When Passive Voice = $$$
Here's the first draft of my summary for a recent Alertbox column, entitled "Tabs, Used Right":
Yahoo Finance follows all 13 design guidelines for tab controls, but usability suffers due to AJAX overkill and difficult customization.
Active voice, yes sir.
Fairly well written, check.
Complete sentence, not a fragment; no disapproving squiggles in Word.
All systems go, except for one nagging question: Does this blurb perform its main job — to attract users who scan SERP listings (search engine results pages) or other lists of possible destinations? No. It fails this mission horribly.
Don't pass Go , don't collect $200.
Users scan Web content in an F-pattern, and often read only the first 2 words of a paragraph. What are the first two words of my draft deck? "Yahoo Finance" — which has zero information scent for article's target audience.
The column in question is about application design, so it needs to attract readers who care about GUI widgets. People who are interested in Yahoo or investments are not the targets.
(I used Yahoo Finance purely as an example in the column; I don't actually discuss the site. I have written about Yahoo as a portal and about investor relations. However, those articles are at other URLs; users attracted by the misleading information scent created by leading with "Yahoo Finance" wouldn't find them.)
Here's the rewritten summary, using passive voice to pull the payoff keywords to the front :
13 design guidelines for tab controls are all followed by Yahoo Finance, but usability suffers due to AJAX overkill and difficult customization.
Because "13" is sufficiently short, users will likely fixate on the first 3 words, not just the first 2, when they initially scan the blurb. Also, numerals beat words when referring to specifics, so starting with "13" is even better at attracting the scanning eye.
So, why not start with "tab controls"? After all, these two words carry the most information for the article and the target audience. The reason is simple: The blurb will always display below the article's headline, which starts with the word "tabs."
Given that users often read only a couple of words from each text element, you should reduce duplication of salient keywords .
Don't use the same initial keywords in your headline and summary. You have 4 words to make your point, so use 4 different words. (Okay, I do bend this guideline a bit for this very article: it leads with "passive voice" in the headline and "active voice" in the summary. But in this case, "voice" is not a keyword on its own — it's not an article about vocalization — and I need to grab people scanning for either active voice or passive voice, and both are 2-word concepts.)
Avoid repeating any headline words in the summary, except for the most important one or two keywords. You can repeat these halfway through the summary to reinforce them for people who scanned past them in the headline.
ROI from Passive vs. Active Voice
Simple sentence structure, active voice, and positive statements have been key Web-writing guidelines for more than a decade. I don't want you to abandon these good ideas. They do improve content usability in most cases, particularly for body text.
However, recent findings from our eyetracking research emphasized the overwhelming importance of getting the first 2 words right, since that's often all users see when they scan Web pages. Given this, we have to bend the writing guidelines a bit, especially for elements that users fixate on when they scan — that is, headlines, subheads, summaries, captions, hypertext links, and bulleted lists.
Words are usually the main moneymakers on a website. Selecting the first 2 words for your page titles is probably the highest-impact ROI-boosting design decision you make in a Web project. Front-loading important keywords trumps most other design considerations.
Writing the first 2 words of summaries runs a close second. Here, too, you might want to succumb to passive voice if it lets you pull key terms into the lead.
The importance of good page titles and summaries goes far beyond traditional search engine optimization (SEO) and its narrow focus on getting a high GYM rating (that is, a high ranking on Google, Yahoo, and Microsoft search listings). Usable and scannable results in your site's own search engine greatly impacts your website's conversion rate. And search usability is key for intranet productivity .
Most text should use simple sentence structure. But sometimes, passive voice can increase ROI. Use it. Carefully.
Full eyetracking report on how users read on the web is available for download.