Task A: Understanding active and passive voice

What will I learn?

• To understand active and passive voice
• Why the passive voice is useful in scientific writing
• Not to overuse the passive voice

What are active and passive voices?

In the active voice, the agent of the sentence (which is the thing doing the action) is before the verb.

For example:

1. Contaminated stock solution caused the death of the population.
    

   The agent (contaminated stock solution) is before the verb (caused).

2. Parasitic worms infected the entire flock.
   
   The agent (parasitic worms) is before the verb (infected).

In the passive voice, the agent of the sentence is after the verb (and is usually preceded by the word ‘by’).

For example:

1. The death of the population was caused by contaminated stock solution.
    

   The agent in this sentence, (contaminated stock solution) is after the verb (caused).�

2. The entire flock was infected by parasitic worms.
   
   The agent (parasitic worms) is after the verb (infected).

In some passive sentences, there is no agent.

For example:

1. The cannula was inserted.
    

   This sentence does not refer to the agent – (the person who inserted the cannula). If it were relevant, the agent may have been included at the end of the sentence, for example:
   The cannula was inserted by the laboratory technician.

2. Measurements of sixteen skulls were taken.
    

   This sentence does not refer to the agent – (the person who took the measurements). If it were relevant, the agent may have been included at the end of the sentence, for example:
   Measurements of sixteen skulls were taken by the researcher.

 

Why the passive voice is useful in scientific writing

Much scientific writing uses the passive voice because it focuses the reader's attention on the object of an action rather than the agency (or doer) of an action.

For example:

1. Contaminated stock solution caused the death of the population.
    

   This sentence, expressed in the active voice, puts the focus on the contaminated stock solution.

2. The death of the population was caused by contaminated stock solution.
    

   This sentence, expressed in the passive voice, emphasises the death of the population.

Using the passive voice and the third person is common, particularly in the Method section of scientific reports. Here the required emphasis is on what was done, rather than who did it. 

For example:

Passive: The rheostat was added to the circuit. 

Active: I added the rheostat to the circuit.

In the second example above, the active voice uses the word ‘I'. In science writing, it is still conventional (if debatable) to avoid using ‘I’ and ‘we’, and this is achieved by using the passive voice.

 

Don’t overuse the passive voice

Overusing the passive voice can make your writing dull, cumbersome and difficult to read. The active voice usually results in shorter, more direct and more precise sentences and for these reasons should be used where appropriate.

Sometimes, the passive voice is ‘distorted’ by adding redundant verbs. The more redundant words you use to express an idea, the more difficult it is to read your writing.

For example:

Active: Water droplets dispersed the spores.

Passive: The spores were dispersed by water droplets.

Passive: Dispersal of the spores was carried out by the action of water droplets.

Where passive voice is used to avoid using the first person, the sentence can sometimes become cumbersome, ambiguous or indirect.

For example:

Passive, 3^rd person: An analysis conducted by the investigator, differed from standard procedure.

Active, 1^st person: I conducted an analysis which differed from standard procedure.

Although it is still very common to use the passive voice, in cases such as the example above, the active voice more honestly acknowledges the human researcher behind the science. Also, it often results in shorter, more direct and more precise sentences, which makes its use preferable (Silyn-Roberts, H. (1996). Writing for Science, Auckland, NZ: Addison Wesley Longman).