Parentheses (singular parenthesis) are felt to be stronger than a comma and similar in weight to an m-dash (—). Parentheses are sometimes called ’round brackets’. Other punctuation can sometimes be substituted for parenthesis, including
- Commas can be used to show an aside to show somewhat less emphasis than parentheses. Example: He finally answered, after taking five minutes to think, that he did not understand the question.
- Dashes can be used instead of parentheses to show even greater emphasis.
Example: He finally answered—after taking five minutes to think—that he did not understand the question.
1. Use parentheses to enclose words or figures that clarify or for an aside. The other possibilities include commas and dashes. Of the possible punctuation choices, parentheses show less emphasis or importance. Examples:
Numbers: I expect about two thousand dollars ($2,000) back from the IRS this year.
Acronyms, foreign words, technical terms, etc.: when establishing the meaning at first use.
The Society for the Protection of Animals (SPCA) requires that all adopted animals be spayed or neutered.
The Dutch use parentheses (variously, ronde haakjes, tussenzin, or pauze) a bit differently than we do.
When giving an example or aside:
Some birds (e.g., Alex, an African gray parrot) have displayed a verbal fluency which may rise to a level linguists would define as language (Pepperberg, 2009).
She’s been dating Nathan (the shy twin) for about six months now.
Citing publication: When citing sources, put the citation inside the sentence when only one sentence is referencing that source, but outside when more than one sentence references it or quotes from it. Important: The way cited material is laid out and handled varies with style book, so take time to check the style appropriate to your discipline. Some general examples:
Within a single sentence:
a) Patricia Kuhl and Andrew Doupe (1999) compared the mechanisms of human speech to birdsong.
b) African Grey parrots (Psittacus erithacus) show a capacity for categorization (Pepperberg, 1983a).
When citing more than one sentence quoted, paraphrased, or referenced generally from a text:
a) Directly Quoted: “The last decade has produced an explosion in neuroscience research examining young children’s early processing of language. Noninvasive, safe functional brain measurements have now been proven feasible for use with children starting at birth.” (Kuhl, 2010)
b) Paraphrased or summarized: Alex Pepperberg Irene Pepperberg strongly believes that African Grey parrots can understand complex concepts, craft unique utterances, and use such utterances in meaning-appropriate situations. She suggests that linguistic studies on non-human species should be expanded from work with the great apes and cetaceans to include various species of birds. (2009)
2. Use parentheses to enclose numbers and letters of listed items in a sentence as well as in outline format. Note: Some systems use a closing half parenthesis within a sentence or in outline format.
Within a sentence, numbers or letters sometimes are given double parentheses, and sometimes just closing parens. Check your style book. Examples:
Single: John’s first request was for an architect capable of working with a) large construction projects, b) very tall structures, and c)
Double: We need a receptionist who can (1) think quickly, (2) direct delivery personnel, and (3) make guests feel comfortable.
Full and closing parentheses are sometimes used in outlines:
I. Fred’s suitcase
a) dress shirts
b) sports shirts
(2) buttoned shirts
3. Periods go inside parentheses only if an entire sentence is inside the parentheses.
Most spare treatment within the sentence:
Please read the analysis (Attachment A). OR
More chatty, also within the sentence:
Please read the analysis (enclosed as Attachment A). OR
As a separate sentence:
Please read the analysis. (I enclosed it as Attachment A.) OR
More rarely (strikes some as a run-on, or fused, sentence):
Please read the analysis (I enclosed it as Attachment A.).
AMA Manual of Style: A Guide for Authors and Editors, 10th ed., Oxford University Press, 2007. Web. 28 June 2014. [See also: AMA Manual of Style.]
American Psychological Association. Publication Manual Of The American Psychological Association, 7th ed. Washington, DC, 2013.
Associated Press. The Associated Press Stylebook and Briefing on Media Law, Basic Books, 2013. [See also: AP Stylebook. Web. 28 June 2014.]
The Chicago Manual of Style. 16th ed. University of Chicago Press, 2010. Web. 28 June 2014. [See also: Chicago-Style Citation Quick Guide.]
The Chicago Manual of Style: Essential Guide for Writers, Editors, and Publishers. 15th ed. University of Chicago Press, 2003. Print.
The MLA Handbook for Writers of Research Papers, 7th ed., Modern Language Association of America, 2009.
MLA Style Manual and Guide to Scholarly Publishing, 3rd ed., Modern Language Association of America, 2008.
The New Oxford Dictionary for Writers and Editors. Oxford University Press, 2005. Web. 29 June 2014.
The New York Times Manual of Style and Usage, Times Books, 1999.
Purdue University. Journal Abbreviation Resources. 16 August 2004. Found 21 December 2005.
Purdue University. “The Owl at Purdue.” 2005. Found December 4, 2005.