Lifespan learning of speech perception in native and non-native listeners

Lifespan learning of speech perception in native and non-native listeners Matthew Davis1 , Samuel Evans1,2*, Kathleen McCarthy1,3*, Anastasia Giannakopoulou1,4*, Lindsey Evans1 * and Joanne Taylor1 1. University of Cambridge 2. Institute for Cognitive Neuroscience, University College London 3. Department of Speech, Hearing and Phonetic Sciences, University College, London 4. University of Bedfordshire Accent differences between early and late second language learners suggest that perception and production of speech has reduced plasticity in adulthood. To explore the nature and cause of these developmental changes we tested perceptual acuity for speech in >2000 visitors to the Science Museum in London. We used an adaptive 3I-2AFC task with two sets of 60 minimal word (e.g. bear-pear), and 60 word-nonword pairs (bag-pag) generated by audio-morphing a number of different phonetic contrasts. Speech was presented with variable proportions of natural acoustic differences and we estimated the Proportion of Acoustic Difference Required for Identification (PADRI): 80% accuracy in deciding which syllable was correct. This PADRI measure shows significant increases of perceptual acuity with age (better acuity for adults), lexical-status (better for word pairs) and language-status (better for native-English listeners). Results suggest that perceptual Wednesday 16 April am 27 Wednesday 16 April am development continues into adolescence and early adulthood. Furthermore, significant interactions between lexical-status and age or language-status suggest that changes in perceptual acuity are most apparent when tested with word-word continua. That both developmental and experience-dependent changes depend on listeners using knowledge of spoken words to guide perception suggests that greater lexical experience may contribute to age-related changes in perceptual plasticity.