Cot–caught merger

The cot–''caught merger, also known as the merger or low back merger, is a phonological phenomenon present in some dialects of English where speakers do not distinguish the vowel phonemes in words like cot versus caught. Cot and caught, along with bot and bought, pond and pawned, etc., are examples of minimal pairs that are lost as a result of this sound change; i.e. each of these pairs of words is pronounced the same. The phonemes involved in the cot–caught merger, the low back vowels, are typically represented in the International Phonetic Alphabet as and or, for United States English, as and. The merger is typical of most Indian, Canadian, and Scottish English dialects as well as some Irish and U.S. English dialects.
An additional vowel merger, the father–bother merger, which spread through North America in the eighteenth and nineteenth centuries, has resulted today in a three-way merger in which most Canadian and many U.S. accents have no vowel difference in words like lexical set|, , and .
However, before does not undergo the merger, participating in a separate phenomenon in most English dialects worldwide: the merger, wherein for instance words like cord and cored are pronounced the same, while card'' is pronounced distinctly.

Overview

The shift causes the vowel sound in words like cot, nod and stock and the vowel sound in words like caught, gnawed and stalk to merge into a single phoneme; therefore the pairs cot and caught, stock and stalk, nod and gnawed become perfect homophones, and shock and talk, for example, become perfect rhymes. The cot–''caught'' merger is completed in the following dialects:

Some English of the British Isles, outside of England:
*Most Scottish English, towards
*Broad and traditional Irish English, towards
*Some northern Ulster English including in conservative mid Ulster English towards and in Ulster Scots English towards
Much of the English of North America:
*Certain varieties of American English, including:
**Pittsburgh English, towards
**Much of New England English towards , and Northern New England generally, but traditionally not Southern New England
**Western American English towards
** Upper Midwestern English, Chicano English, and some Western New England English towards
*Nearly all Canadian English, including:
**Standard Canadian English towards
**Maritimer and Newfoundland English, towards
Much Indian English towards or
Some Singaporean English

or '	'	IPA
bobble	bauble
body	bawdy
bot	bought
box	balks
chock	chalk
clod	clawed
cock	caulk
cod	cawed
collar	caller
cot	caught
don	dawn
fond	fawned
hock	hawk
holler	hauler
hottie	haughty
knot	nought
knotty	naughty
nod	gnawed
not	nought
odd	awed
pod	pawed
pond	pawned
rot	wrought
sod	sawed
sot	sought
stock	stalk
tot	taught
wok	walk

North America

The presence of the merger and its absence are both found in many different regions of the North American continent, where it has been studied in greatest depth, and in both urban and rural environments. The symbols traditionally used to transcribe the vowels in the words cot and caught as spoken in American English are and, respectively, although their precise phonetic values may vary, as does the phonetic value of the merged vowel in the regions where the merger occurs.
Even without taking into account the mobility of the American population, the distribution of the merger is still complex; there are pockets of speakers with the merger in areas that lack it, and vice versa. There are areas where the merger has only partially occurred, or is in a state of transition. For example, based on research directed by William Labov in the 1990s, younger speakers in Kansas, Nebraska, and the Dakotas exhibited the merger while speakers older than 40 typically did not. The 2003 Harvard Dialect Survey, in which subjects did not necessarily grow up in the place they identified as the source of their dialect features, indicates that there are speakers of both merging and contrast-preserving accents throughout the country, though the basic isoglosses are almost identical to those revealed by Labov's 1996 telephone survey. Both surveys indicate that, as of the 1990s, approximately 60% of American English speakers preserved the contrast, while approximately 40% merged the phonemes. Further complicating matters are speakers who merge the phonemes in some contexts but not others, or merge them when the words are spoken unstressed or casually but not when they are stressed.
Speakers with the merger in northeastern New England still maintain a phonemic distinction between a fronted and unrounded and a back and usually rounded , because in northeastern New England, the cot–''caught merger occurred without the father–bother merger. Thus, although northeastern New Englanders pronounce both cot and caught as, they pronounce cart as.
Labov et al. also reveal that, for about 15% of respondents, a specific – merger before but not before is in effect, so that Don and dawn are homophonous, but cot and caught are not. In this case, a distinct vowel shift is taking place, identified as the Don–dawn'' merger.

Resistance

According to Labov, Ash, and Boberg, the merger in North America is most strongly resisted in three regions:

The "Inland North", encompassing the eastern and central Great Lakes region
The "Northeast Corridor" along the Atlantic coast, ranging from Baltimore to Philadelphia to New York City to Providence. However, the merger is common in Boston and further northern New England.
The "South", somewhat excluding Texas and Florida.

In the three American regions above, sociolinguists have studied three phonetic shifts that can explain their resistance to the merger. The first is the fronting of found in the Inland North, in which the vowel is advanced as far as the cardinal , thus allowing the vowel to lower into the phonetic environment of without any merger taking place. The second situation is the raising of the vowel found in Providence, New York City, Philadelphia, and Baltimore, in which the vowel is raised and diphthongized to, or, less commonly,, thus keeping that vowel notably distinct from the vowel. The third situation occurs in the South, in which vowel breaking results in being pronounced as upgliding, keeping it distinct from. None of these three phonetic shifts, however, is certain to preserve the contrast for all speakers in these regions. Some speakers in all three regions, particularly younger ones, are beginning to exhibit the merger despite the fact that each region's phonetics should theoretically block it.
African-American Vernacular English accents have traditionally resisted the cot–''caught merger, with pronounced and traditionally pronounced, though now often. Early-2000s research has shown that this resistance may continue to be reinforced by the fronting of, linked through a chain shift of vowels to the raising of the,, and perhaps vowels. This chain shift is called the "African American Shift". However, there is still evidence of AAVE speakers picking up the cot–caught'' merger in Pittsburgh, Pennsylvania, in Charleston, South Carolina, in Florida and Georgia, and in parts of California.

Origin

In North America, the first evidence of the merger comes from western Pennsylvania as far back as the data shows. From there, it entered Upper Canada. In the mid-19th century, the merger also independently began in eastern New England, possibly influencing the Canadian Maritimes, though the merger is in evidence as early as the 1830s in both regions of Canada: Ontario and the Maritimes. Fifty years later, the merger "was already more established in Canada" than in its two U.S. places of origin. In Canadian English, further westward spread was completed more quickly than in English of the United States.
Two traditional theories of the merger's origins have been longstanding in linguistics: one group of scholars argues for an independent North American development, while others argue for contact-induced language change via Scots-Irish or Scottish immigrants to North America. In fact, both theories may be true but for different regions. The merger's appearance in western Pennsylvania is better explained as an effect of Scots-Irish settlement, but in eastern New England, and perhaps the American West, as an internal structural development. Canadian linguist Charles Boberg considers the issue unresolved. A third theory has been used to explain the merger's appearance specifically in northeastern Pennsylvania: an influx of Polish- and other Slavic-language speakers whose learner English failed to maintain the distinction.