Scientific writing is recognised as being difficult to read, dense and boring. Part of these criticisms come from breaking one of the core writing “rules”: use of the passive voice. Or, perhaps that should be “passive voice is used in scientific writing”. If using the passive voice isn’t “good” writing, why is it so common? This post is about the where, when, and why of passive constructions, and, importantly, identifying opportunities where it is beneficial to edit your text to use the active form.
All three of these sentences are easily understood. However, if you look at the poll results, you (presumably) will see that the “we investigated” form is the preferred option. Despite this, the two non-preferred options are more common in formal science writing. Why is that and is it a good or bad thing?
Let’s quickly deal with the fundamentals. Whenever your readers start reading a sentence, they want to get organised. They want to know whose story the sentence is telling, the “subject”. They also want to know the person/thing responsible for an action, the “agent”. When you use the active voice, the agent and the subject are the same, whereas in the passive, agency is deferred or implied. A simple way to think about this is “agent::action::outcome” = active, outcome::action::agent = passive. Perhaps even simpler is to look at the verb form, if it is “was or were” then the sentence is probably passive voice.
- Active voice- Agent::action::outcome
- Passive voice – Outcome::action::(agent)
We can apply this to our example sentences:
- Active: We investigated the role of laminins in basement membrane assembly. [whose story is it? = “we”, who is the agent? = “we”].
- Passive: The role of laminins in basement membrane assembly was investigated. [whose story? = “laminins”, agent? = not present but is implied “by us” but could be others].
- Passive: An investigation into the role of laminins in basement membranes was conducted. [whose story? = “an investigation”, agent? = not present, implied “by us”]
The active voice can be clearer, it certainly uses fewer words, and, importantly, it makes your writing feel dynamic. If you are writing for a non scientific audience (e.g. a lay summary, press release, blog post), then deliberately editing your work into the active voice is a good idea. However, using the active voice was/is frowned upon in academic scripts. Good news is that times are changing. Nature Publishing Group, for example, “prefer authors to write in the active voice… as experience has shown that readers find concepts and results to be conveyed more clearly when written directly.” It is amusing to note that “to be conveyed” is a passive construction in that statement, we all find it hard to break the habit! Therefore the obvious question is; why do we use the passive voice so often? Let’s have a look at the potential benefits of the passive voice?
Why should we use the passive voice? 4 good reasons
In the example sentences, we saw that by using the passive voice we can omit agency. In science writing, the things that we are writing about don’t have agency. The story we are telling is the story of the cells, the molecules, the proteins, the experimental organisms. It is not about who did the work but rather it is about the results of that work. Passive voice allows you to maintain a consistent perspective and, importantly, focus your readers’ attention onto the correct place. Passive voice can imbue your writing with a sense of objectivity that otherwise might not be there.
2. Continuity and Flow
Context matters. Compare these two sentences:
- 1- Active voice: LaNts regulate the proteolytic processing of laminins
- 2- Passive voice; Laminin proteolytic processing is regulated by LaNts.
Both sentences are absolutely fine on their own, but which would be best depends on the context. Sentence 1, the active version, would be used in a paragraph that is about LaNts. In contrast, the the passive voice option would be in a paragraph that is focused on laminins.
As a general rule, you should change viewpoint infrequently. At the paragraph level, the delivery of the overall message is much clearer for our readers if we maintain a consistent viewpoint. Even better, if you can maintain the same viewpoint throughout the document then your narrative will feel connected. Using passive voice might allow you to stay consistent.
3. Accuracy and precision
Making the scientist the agent in the sentence isn’t the only way to convert a sentence to the active voice, you can also assign agency to the cells/proteins. However, the meaning might change. Compare the following.
- Active voice: Elevated netrin-4 expression levels are associated with vascular disruption.
- Passive voice: Elevated netrin-4 expression levels have been associated with vascular disruption.
“Are” has changed to “have been”, and this change has dramatically changed the message. The active version is confident and definitive. It doesn’t leave any room for doubt. In contrast, the passive version is more precise but also more restricted. It allows room for alternative interpretation and for other data to reveal something different. Choosing between these types of construction allow you, as the writer, to differentiate between the strength of inferences. This is a powerful tool that you will use again and again in your literature review, and discussion sections. Your language should agree with the quality of supporting evidence. I would expect the active sentence to be supported by 3+ refs (and possibly a meta analysis) whereas the passive voice might have just one ref.
- Active voice: Laminin a3 bound to b4 integrin with high affinity.
- Passive voice: b4 integrin was bound by laminin a3 with high affinity.
The strengths and limitations of your experimental design should be reflected by the language used to describe it. The active voice here is stronger, but this a situation where the origin of the data determines the answer. If this sentence was describing the results from an assay where one of the proteins was immobilised on a substrate and then the other protein added in solution over the top, then the sentence construction would have to reflect that design (passive voice, was bound). However, if the same experiment was repeated with the positions reversed then the active voice could become the better option. We usually aim for “triangulation” in science; asking the same question in multiple ways to increase our confidence in the results. However, that isn’t always possible and we are forced into passive constructions.
4. When you don’t have a choice!
The fourth time to use passive voice instead of active is when there are official rules and you can’t change them! In our case, materials and methods sections. The only potential agency in methods is the “we” as the scientists doing the work, but the rules are that you must write methods sections in the third person. It is possible to give agency to things, but you can only assign agency where it is accurate. Experimental animals simply don’t have agency if it is the scientist who is in control; “mice were mated”. Even human subjects in an observational study are still being observed! Be aware, that the passive voice for methods rule continues to apply when you are using any rationale statements. You must say something like “Conditions were selected…” rather than “We selected…”. [note for new writers, rationale statements aren’t usually required in a methods section. If you need them, they often work better within the results section.] Methods section writing guide here.
Science writing opportunities to use the active voice (or are they?)
OK, so we should acknowledge that passive voice is necessary but active sounds better. Therefore, we should ask when can we use active. Let’s try a few small polls to discover what you think about specific situations. Click your answer, and you will see how others have responded
My opinion: Most often, the experimental hypotheses will have been established based on prior literature or previous results, and not purely from your thinking. You shouldn’t claim ownership to others thoughts; therefore, the default position is the passive voice. Science (with a capital S) doesn’t care who did the “hypothesising”. However, there can be rare occasions when active voice not only is appropriate but also works best. For example, it could be a compare/contrast situation “Although the data suggest X, we hypothesised Y”.
In grant applications or project proposals, ownership of a thought process is relevant to your readers and, where justified, is likely to be the best choice. The big difference in these situations, of course, is that the funders are supporting the people in addition to the project. You are relevant!
My opinion: either is fine but here I would lean toward the active. Although it doesn’t matter who did the work, in this type of sentence it doesn’t distract from the narrative and there is benefit from being a little more dynamic and accessible.
A note of caution. I do not recommend back-to-back “we” sentences; “We aimed to determine….”/ “therefore we …..”. Remember that the transition to accepting active voice in science writing is relatively recent and your work will be read and reviewed by people who still consider it entirely wrong to use first person constructions. On that basis, I suggest a limit of one “we” per results subsection to ensure you don’t go too far and annoy your readers. Results writing guide here.
My opinion: the “the findings described here”. This is true despite it being longer and clunkier! The findings in a manuscript are not yours, they belong to Science (I’m really loving that capital S). Simple as that. Both are active voice, so you actually don’t gain much by using “our” in this context anyways, except projecting a poor understanding of why research is done!
Is there an exception? Perhaps one could argue that a situation of “our findings suggest X, whereas work from Author et al, showed Y”. That is a nice clean sentence to highlight controversy, but you could also do so by saying; “the findings reported here suggest X, whereas previous work has shown Y”. In a discussion or a literature review these sorts of side-by-side comparisons are common, so watch out for times where a little edit can help you to sound more objective.
#1 suggestion, as always, write your first draft without worrying about any of this. Don’t worry about sentence-level edits until later in the process. However, once you are at the stage where the structure and narrative flow are set, then making small edits to turn passive constructions into active voice can make your writing more dynamic and enjoyable for your reader, or turning active into passive can make your writing objective and precise.
in science writing:
- Put the agency in the Science rather than the scientists.
- Don’t disrupt your paragraph/document flow when passive voice allows you to keep the viewpoint consistent.
- Check that use of active voice is supported by your experimental design.
- Use passive voice for all materials and methods.
- Don’t claim ownership of things that can’t be owned (results).
Check out the previous editing for impact post on applying emphasis:
Or you might like some of our other writing resources…