by Chelsea Lee
Academic writing is full of little conventions that may seem opaque to the uninitiated. One of these is the Latin phrase et al., an abbreviation meaning “and others.” It is used to shorten lists of author names in text citations to make repeated referencing shorter and simpler. Note that et al. is italicized in this post when I am using it as a linguistic example, but it should not be italicized when you are using it as part of a reference citation.
General Use of Et Al.
Below is a chart showing when to use et al., which is determined by the number of authors and whether it is the first time a reference has been cited in the paper. Specifically, articles with one or two authors include all names in every in-text citation; articles with three, four, or five authors include all names in the first in-text citation but are abbreviated to the first author name plus et al. upon subsequent citations; and articles with six or more authors are abbreviated to the first author name plus et al. for all in-text citations.
|
Number of authors |
First text citation (either parenthetical or narrative) |
Subsequent text citations (all) |
|
One or two |
Palmer & Roy, 2008 |
Palmer & Roy, 2008 |
|
Three, four, or five |
Sharp, Aarons, Wittenberg, & Gittens, 2007 |
Sharp et al., 2007 |
|
Six or more |
Mendelsohn et al., 2010 |
Mendelsohn et al., 2010 |
Avoiding Ambiguity
However, sometimes abbreviating to the first author name plus et al. can create ambiguity. Here are two example references, as also discussed in a previous post about reference twins.
| Marewski, J. N., Gaissmaier, W., & Gigerenzer, G. (2010). Good judgments do not require complex cognition. Cognitive Processing, 11, 103–121. doi:10.1007/s10339-009-0337-0 |
| Marewski, J. N., Gaissmaier, W., Schooler, L. J., Goldstein, D. G., & Gigerenzer, G. (2010). From recognition to decisions: Extending and testing recognition-based models for multi-alternative inference. Psychonomic Bulletin & Review, 17, 287–309. doi:10.3758/PBR.17.3.287 |
The first in-text citations to each of these would be as follows:
- (Marewski, Gaissmaier, & Gigerenzer, 2010)
- (Marewski, Gaissmaier, Schooler, Goldstein, & Gigerenzer, 2010)
For the subsequent in-text citations we would usually abbreviate these studies to the first author name plus et al.; however, doing so here would produce two Marewski et al. (2010) citations, leaving the reader unable to tell which one you mean (if the citations were from different years we would not have this problem, because the years would tell them apart). The solution here is to spell out as many names as necessary (here, to the third name) upon subsequent citations to tell the two apart:
- (Marewski, Gaissmaier, & Gigerenzer, 2010)
- (Marewski, Gaissmaier, Schooler, et al., 2010)
Notice that for the first reference, this means that all citations to this source include all three names. For the second reference, the two remaining names can be abbreviated to et al.
A Quirk of Et Al.
Finally, be careful of a quirk of et al., which is that it is plural—that is, it must replace at least two names (or, put another way, it cannot stand for only one name). So, if you have worked through a reference and only one name is left to abbreviate, you must spell out all the names every time to tell the two apart. Here is an example with three authors, although the principle holds no matter how many total authors there are:
| Berry, C. J., Henson, R. N. A., & Shanks, D. R. (2006). On the relationship between repetition priming and recognition memory: Insights from a computational model. Journal of Memory and Language, 55, 515–533. doi:10.1016/j.jml.2006.08.008 |
| Berry, C. J., Shanks, D. R., & Henson, R. N. A. (2006). On the status of unconscious memory: Merikle and Reingold (1991) revisited. Journal of Experimental Psychology: Learning, Memory, and Cognition, 32, 925–934. doi:10.1037/0278-7393.32.4.925 |
The correct in-text citations would be written as follows for all citations of these two references:
- (Berry, Henson, & Shanks, 2006)
- (Berry, Shanks, & Henson, 2006)
Avoid the following common incorrect ways of citing these references in text:
- (Berry, Henson, et al., 2006), (Berry et al., 2006a)
- (Berry, Shanks, et al., 2006), (Berry et al., 2006b)
A Final Note
If it happens that all the author names are exactly the same and the studies were published in the same year as well, the method of citation described in the reference twins post applies. Namely, use et al. as usual but also include lowercase letters after the year (2010a, 2010b, etc.) to tell the references apart.
For more information and examples on citing references in text, see Chapter 6 of our sixth edition Publication Manual (pp. 174–179). You may also be interested in our primer on how in-text citations work and our piece on common et al.-related errors.