The cot–caught merger or merger, formally known in linguistics as the low back merger, is a sound change present in some dialects of English where speakers do not distinguish the vowel phonemes in "cot" and "caught". "Cot" and "caught" (along with "bot" and "bought", "pond" and "pawned", etc.) is an example of a minimal pair that is lost as a result of this sound change. The phonemes involved in the cot–caught merger, the low back vowels, are typically represented in the International Phonetic Alphabet as and , respectively (in the U.S., co-occurring with the father–bother merger, as and ). The merger is typical of most 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 "palm" , "lot" , and "thought" . However, as in "North" is generally not merged. In dialects with the north-force merger, this can be phonemicized as , thus . 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 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 (with the father–bother merger) Much of New England English towards (in Boston, particularly towards ), and Northern New England generally, however traditionally not Southern New England Western American English (with the father–bother merger) towards Cajun English, Upper Midwestern English, and Chicano English (with the father–bother merger) towards Nearly all Canadian English, including: Standard Canadian English towards (with the father–bother merger) Maritimer and Newfoundland English, towards (with the father–bother merger) Much Indian English towards or Some Singaporean English North American English Nowhere is the shift more complex than in North American English. The presence of the merger and