Hi, this is Karen McKee, author and retired scientist.
Today, I'm going to talk about active versus passive voice in scientific writing.
Let me start with what is meant by active voice.
Some people misunderstand, and think that active voice only involves a first-person
pronoun.
A famous example is the first sentence of Watson and Crick's 1953 paper.
We wish to suggest a structure for the salt of deoxyribose nucleic acid (D.N.A.).
This sentence uses active voice, but not because of the first-person pronoun, we.
It's active because the subject of the sentence is doing the action.
This sentence is also written in active voice.
Squirrels ate the acorns.
A sentence written in passive voice, on the other hand, has the subject acted upon by
the verb.
The acorns were eaten by squirrels.
Here's another example.
Salinity reduced plant growth is active.
Plant growth was reduced by salinity is passive.
If you're still confused, there is a handy tip that copy editors use.
If you can append the phrase, by zombies, to the end of a sentence and it still makes
sense, it's passive.
For example, the soil samples were collected by zombies.
This sentence makes grammatical sense, which means it is passive.
Sometimes a passive sentence will omit the actor entirely in an attempt to highlight
a problem without assigning blame.
The laboratory door was left open.
Samples were lost.
Mistakes were made.
In scientific writing, the passive voice is used because it supposedly sounds more scholarly
and imparts a tone of detachment and humility.
But use of the passive voice in scientific writing is a big part of why technical writing
can sound stilted and robotic.
The active voice makes sentences come alive.
And also tends to require fewer words.
For example, consider this.
The leaves were subjected to isotopic analysis to assess plant nutrient sources.
Versus.
Isotopic analysis of leaves revealed plant nutrient sources.
The active construction in the latter sentence is more dynamic and requires fewer words.
However, there are instances in which the passive voice is the proper choice.
For example, use passive voice when it makes sense to emphasize the receiver of the action.
Readers expect a unit of discourse such as a sentence to be a story about whoever or
whatever is mentioned first, that is, in the topic position.
The example I gave earlier was squirrels ate the acorns, which is active construction.
Versus acorns are eaten by squirrels, which is passive.
The active version suggests the focus is on squirrels, whereas the passive version indicates
the focus is on oak trees or seed dispersal.
If your topic is oak trees and acorns, you want to use the passive voice version because
this tells the reader that you are going to be talking mainly about acorns, not squirrels.
You might also use passive voice for variety or when the flow of the paragraph would be
improved.
For example.
One aspect of plant flood tolerance can be understood through an examination of root
airspace tissue.
Passive voice is also often used in the Methods or Experimental section of a paper.
As such, passive construction is not only appropriate but often preferred in describing
the methods.
Passive voice can also be used effectively in an abstract, in combination with active
constructions.
Here, for example, is an excerpt from an abstract.
Experimental plots were established in spatially equivalent positions.
Of course, you could also say that we established experimental plots.
But first-person pronouns often put the emphasis on the researcher rather than on the research.
Use such pronouns sparingly.
To summarize, you can use active voice to liven up your writing and be less wordy at
the same time.
These considerations must be balanced, however, against what subject you wish to emphasize
and if passive construction is more appropriate.
The key is to make your selections coincide with the reader's needs and expectations.
I hope you will feel more confident now about using both active and passive voice in your
scientific writing.
Thanks for watching and please like my video if you found it informative.