Dissertation: Perception of Handshape in ASL

[Mark A. Mandel]

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  Message 1: The Perception of Handshape in American Sign Language

   Date: Fri, 27 Feb 2004 09:53:48 -0500 (EST)
   From: sbaker <sbaker at dartmouth.edu>
   Subject: The Perception of Handshape in American Sign Language

Institution: University of Delaware
Program: Department of Linguistics
Dissertation Status: Completed
Degree Date: 2002

Author: Stephanie Ann Baker

Dissertation Title: The Perception of Handshape in American Sign
Language

Linguistic Field: Applied Linguistics, Phonolgy, Psycholinguistics

Subject Language: American Sign Language (code: ASE)

Dissertation Director 1: William James Idsardi
Dissertation Director 2: Roberta Golinkoff
Dissertation Director 3: Irene Vogel
Dissertation Director 4: Laura-Ann Petitto

Dissertation Abstract:

Categorical perception (CP) refers to the finding that certain stimuli
from a continuum are perceived as members of discrete categories.
Thus, despite the fact that the stimuli vary continuously, they are
perceived discretely.  In adults, CP for speech sounds has also been
shown to be language-specific and a result of linguistic experience
with the particular speech contrast being tested.  Additional research
demonstrated that some non-human mammals exhibited CP for certain
speech contrasts (e.g., Kuhl, 1981), and that humans also exhibited CP
for non-linguistic stimuli such as colors (Bornstein, 1987) and faces
(Beale & Keile, 1995; Etcoff & Magee, 1992).  The current view
of CP is that it is driven by domain general processing mechanisms
(Kuhl, 2000).  The role of linguistic experience for CP remains an
unresolved issue, however.  If linguistic experience were of no
importance in CP, then the effects for speech stimuli should not be
language-specific.  The fact that at least some cases of CP are
language-specific raises the potential that humans have developed
special abilities for perceiving distinctions that are relevant to
their native language.

The focus of the research for this dissertation is the role of
linguistic experience for a set of contrasts that is simultaneously
perceptual (visual) and linguistic.  One experiment with two tasks
investigated whether Deaf signers or hearing nonsigners exhibit CP for
handshape contrasts in American Sign Language (ASL).  CP performance
was measured using forced choice identification and AX discrimination
paradigms with digital images of a native signer articulating the
handshapes.

The results showed that only the ASL signers exhibited categorical
perception for the handshape contrasts.  These results suggest that
the ASL signers have developed unique abilities for perceiving
distinctions that are relevant to ASL, similar to the abilities that
hearing speakers have developed for perceiving spoken language.  These
results also suggest that linguistic CP is a result of dedicated
mechanisms that are language-specific rather than general-perceptual,
since only the ASL signers, who had linguistic experience with the
stimuli, exhibited CP for the handshapes.