second, replacing a third, in a complete chain). In the Atlas of North American English (2006), he and his co-authors find three major divergent chain shifts taking place today: a Southern Shift (in Appalachia and southern coastal regions); a Northern Cities Vowel Shift affecting a region from Madison, Wisconsin, east to Utica, New York; and a Canadian Shift affecting most of Canada, as well as some areas in the Western and Midwestern (Midland) United States, in addition to several minor chain shifts in smaller regions. Among Labov's well-known students are Charles Boberg, Anne H. Charity Hudley, Penelope Eckert, Gregory Guy, Robert A. Leonard, Geoffrey Nunberg, Shana Poplack, and John R. Rickford. His methods were adopted in England by Peter Trudgill for Norwich speech and K. M. Petyt for West Yorkshire speech. Labov's works include The Study of Nonstandard English (1969), Language in the Inner City: Studies in Black English Vernacular (1972), Sociolinguistic Patterns (1972), Principles of Linguistic Change (vol.I Internal Factors, 1994; vol.II Social Factors, 2001, vol.III Cognitive and Cultural factors, 2010), and, with Sharon Ash and Charles Boberg, The Atlas of North American English (2006). Labov was awarded the 2013 Benjamin Franklin Medal in Computer and Cognitive Science by the Franklin Institute with the citation "[f]or establishing the cognitive basis of language variation and change through rigorous analysis of linguistic data, and for the study of non-standard dialects with significant social and cultural implications." Language in use In "Narrative Analysis: Oral Versions of Personal Experience", Labov and Joshua Waletzky take a sociolinguistic approach to examine how language works between people. This is significant because it contextualizes the study of structure and form, connecting purpose to method. His stated purpose is to "isolate the elements of narrative". This work focuses exclusively on oral narratives. Labov describes narrative as having two functions: referential and evaluative, with its referential functions orienting and grounding a story in its contextual world by referencing events in sequential order as they originally occurred, and its evaluative functions describing the storyteller's purpose in telling the story. Formally analyzing data from orally generated texts obtained via observed group interaction and interview (600 interviews were taken from several studies whose participants included ethnically diverse groups of children and adults from various backgrounds), Labov divides narrative into five or six sections: Abstract – gives an overview of the story. Orientation – Labov describes this as "referential [free clauses that] serve