Effects of language experience on the perception of American Sign Language

Abstract

Perception of American Sign Language (ASL) handshape and place of articulation parameters was investigated in three groups of signers: deaf native signers, deaf non-native signers who acquired ASL between the ages of 10 and 18, hearing non-native signers who acquired ASL as a second language between the ages of 10 and 26. Participants were asked to identify and discriminate dynamic synthetic signs on forced choice identification and similarity judgement tasks. No differences were found in identification performance, but there were effects of language experience on discrimination of the handshape stimuli. Participants were significantly less likely to discriminate handshape stimuli drawn from the region of the category prototype than stimuli that were peripheral to the category or that straddled a category boundary. This pattern was significant for both groups of deaf signers, but was more pronounced for the native signers. The hearing L2 signers exhibited a similar pattern of discrimination, but results did not reach significance. An effect of category structure on the discrimination of place of articulation stimuli was also found, but it did not interact with language background. We conclude that early experience with a signed language magnifies the influence of category prototypes on the perceptual processing of handshape primes, leading to differences in the distribution of attentional resources between native and non-native signers during language comprehension.

Effects of sign language experience on categorical perception of dynamic ASL pseudosigns

“…A core question is why we, as well as Newport (1982) and Morford et al (2008), failed to find the classic pattern of categorical perception of minimal handshape contrasts in native signers, whereas the other two prior studies reported finding it for some handshape contrasts Emmorey et al, 2003). Among the potential reasons for the discrepant findings, as discussed earlier, are stimulus and methodology differences.…”

“…The categorical studies have focused mainly on handshape contrasts, although they have examined a more restricted number and type of location contrasts. The few location contrasts investigated in categorical perception studies have shown neither the categorical patterns seen in speech studies nor any effects of sign language experience Morford et al, 2008;Newport, 1982). Movement contrasts, however, have not been examined yet via categorical perception techniques.…”

“…Inspection of published discrimination functions also suggests inconsistent interpretations of categoricity. Specifically, the general shape and level of discrimination functions are fairly similar (and shallow rather than steeply peaked) on A-bar versus B-bar for hearing controls, said to lack categorical perception ( ) , and for native signers, who were said to display categorical perception ( ) of that contrast Emmorey et al, 2003); but [ ] in Morford et al, 2008), as well as on 5 versus flat-O . Conversely, signers' discrimination function on A-bar versus B-bar ( ) differs from that for 5 versus 3, which yielded rather similar discrimination functions in signers ( ) and controls ( ), despite opposing claims about categoricity .…”

“…Given their aim to identify perception of phonetic contrasts per se, most categorical speech perception studies have used permissible nonword contrasts in order to minimize lexical biases, and have used computer-controlled stimulus generation to ensure physically equal step sizes and to eliminate other extraneous variation along the continuum. Morford et al (2008) did use a computer-synthesized dynamic sign continuum; however, the signs were meaningful, leaving open the possibility of lexical bias, as they acknowledged.…”

The impact of input quality on early sign development in native and non-native language learners

“…Linked to this possibility are sign perception studies by Best, Mathur, Miranda, and LilloMartin (2010) and Morford et al (2008) that suggest sparser input could discourage categorization and hence lead to maintenance of sensitivity to phonetic contrasts to a higher degree in late than in native signers.…”