passive and active voice

An author may write a sentence in one of two "voices"—active or passive.The active voice emphasizes the performer (or agent) of the action:Wind disperses plant seeds.Smith et al. investigated the relationship.We have analyzed the results.The active voice is direct (performer–verb–receiver), vigorous, clear, and concise. The reader knows who is responsible for the action.

The passive voice, in contrast, emphasizes the receiver (or product) of the action:Plant seeds are dispersed [by wind].The relationship was investigated [by Smith et al].The results have been analyzed [by us].The passive voice is indirect (receiver–verb–performer) and can be weak, awkward, and wordy. Passive voice uses a form of the verb to be followed by a past participle (e.g., dispersed, investigated) and a by phrase. If the by phrase is omitted (the truncated passive), the reader will not directly know who or what performed the action.A particularly awkward and ambiguous form of the passive voice occurs when an author uses it as the receiver rather than the first-person pronouns I or we:It is concluded that the treatment is effective.These types of passive-voice sentences are a form of hedging.In addition to being awkward, sentences written in the passive voice, if not constructed carefully, may contain grammatical errors such as dangling modifiers.Changing from passive to active voice corrects the error and strengthens the sentence:Dangling: To investigate the source of nutrients, eggshell membranes were compared. (incorrect passive)Correction: To investigate the source of nutrients, we compared eggshell membranes. (active)Dangling: After analyzing the samples, the plants were measured daily. (incorrect passive)Correction: After analyzing the samples, we measured the plants daily. (active)Despite these disadvantages, the passive voice has a legitimate place in writing. In addition to allowing an author to vary the sentence structure, the passive voice has other important functions. To learn more, see "The Value of the Passive Voice."

Tradition and the Passive Voice

More than a century ago, scientists typically wrote in an active style that included the first-person pronouns I and we. Beginning in about the 1920s, however, these pronouns became less common as scientists adopted a passive writing style.Considered to be objective, impersonal, and well suited to science writing, the passive voice became the standard style for medical and scientific journal publications for decades.There were exceptions, however. For instance, in 1953, one elegantly written paper began:

Here are examples of sentences written in both the active voice and the passive voice, with the active voice sentence appearing first:

1.andi  ate six shrimp at dinner. (active)

  At dinner, six shrimp were eaten by Harry. (passive)

2.Beautiful giraffes roam the savannah. (active)

  The savannah is roamed by beautiful giraffes. (passive)

3.Sue changed the flat tire. (active)

  The flat tire was changed by Sue. (passive)

4.We are going to watch a movie tonight. (active)

  A movie is going to be watched by us tonight. (passive)

5.I ran the obstacle course in record time. (active)

  The obstacle course was run by me in record time. (passive)

6.The crew paved the entire stretch of highway. (active)

  The entire stretch of highway was paved by the crew. (passive)

7.Mom read the novel in one day. (active)

  The novel was read by Mom in one day. (passive)

8.e critic wrote a scathing review. (active)

  A scathing review was written by the critic. (passive)

9.I will clean the house every Saturday. (active)

  The house will be cleaned by me every Saturday. (passive)

10.The staff is required to watch a safety video every year. (active)

  A safety video will be watched by the staff every year. (passive)

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