Classi¿ cation of Regional Language Varieties 215more confusable than non-local varieties. Geographic mobility, on the other
hand, served to create more ¿ ne-grained distinctions among different varie-
ties, perhaps reÀ ecting more robust cognitive representations of dialect vari-
ation, and attenuating the locality effect. Additional research is needed to
determine whether listeners can be trained to perform these types of tasks
more accurately, at what levels of performance they reach an asymptote, and
the relationship between speci¿ c acoustic properties and dialect classi¿ cation
performance.
- New directions
Sociophonetic research on the perception of dialect variation has revealed
several major ¿ ndings that complement earlier speech science research on the
perception of linguistic and social categories. First, the results of the vowel
identi¿ cation tasks (Labov and Ash 1998; Rakerd and Plichta 2003) suggest
that linguistic context is an important factor in the perception of shifted vowel
systems. When the semantic context is suf¿ cient to predict the target word,
recognition performance is good, regardless of the match between the dia-
lects of the talker and the listener (Labov and Ash 1998). However, when
the semantic context is ambiguous, word recognition is impaired for non-
local listeners (Labov and Ash 1998; Rakerd and Plichta 2003). Second, the
dialect classi¿ cation and discrimination studies provide evidence for poorly-
speci¿ ed perceptual dialect categories. The results of the free classi¿ cation
task (Clopper and Pisoni 2007) and the similarity ratings task (Clopper et al.
2006) in particular suggest that naïve listeners have dif¿ culty mapping acous-
tic variability to speci¿ c dialect representations.
Finally, in both the vowel identi¿ cation and dialect classi¿ cation experi-
ments, the linguistic experience of the listeners was an important factor in
determining performance. First, region of origin had a signi¿ cant effect on
the listeners’ ability to adapt to vowel shifts in the vowel identi¿ cation tasks
(Labov and Ash 1998; Rakerd and Plichta 2003). Listeners also showed greater
accuracy overall in categorizing talkers from their own dialect region in the
dialect classi¿ cation task (Clopper and Pisoni 2004), as well as a tendency to
perceive their own dialect as more similar to neighboring dialects than to more
geographically distant varieties (Clopper 2004; Clopper and Pisoni 2006).
Second, geographic mobility had a signi¿ cant effect on the listeners’ classi¿ -
cation behavior. Geographically mobile listeners were more accurate in their
categorization judgments overall (Clopper and Pisoni 2004) and exhibited
greater discrimination between their own dialects and neighboring dialects