What Makes Lexical Tone Special: A Reverse Accessing Model for Tonal Speech Perception

Representational level matters for tone-word recognition: Evidence from form priming

In a form priming experiment with a lexical decision task, we investigated whether the representational structure of lexical tone in lexical memory impacts spoken-word recognition in Mandarin. Target monosyllabic words were preceded by five types of primes: (1) the same real words (/lun4/-/lun4/), (2) real words with only tone contrasts (/lun2/-/lun4/), (3) unrelated real words (/pie3/-/lun4/), (4) pseudowords with only tone contrasts (*/lun3/-/lun4/), and (5) unrelated pseudowords (*/tai3/-/lun4/). We found a facilitation effect in target words with pseudoword primes that share the segmental syllable but contrast in tones (*/lun3/-/lun4/). Moreover, no evident form priming effect was observed in target words primed by real words with only tone contrasts (/lun2/-/lun4/). These results suggest that the recognition of a tone word is influenced by the representational level of tone accessed by the prime word. The distinctive priming patterns between real-word and pseudoword primes are best explained by the connectionist models of tone-word recognition, which assume a hierarchical representation of lexical tone.

Neurophysiological evidence for goal-oriented modulation of speech perception

Speech perception depends on the dynamic interplay of bottom-up and top-down information along a hierarchically organized cortical network. Here, we test, for the first time in the human brain, whether neural processing of attended speech is dynamically modulated by task demand using a context-free discrimination paradigm. Electroencephalographic signals were recorded during 3 parallel experiments that differed only in the phonological feature of discrimination (word, vowel, and lexical tone, respectively). The event-related potentials (ERPs) revealed the task modulation of speech processing at approximately 200 ms (P2) after stimulus onset, probably influencing what phonological information to retain in memory. For the phonological comparison of sequential words, task modulation occurred later at approximately 300 ms (N3 and P3), reflecting the engagement of task-specific cognitive processes. The ERP results were consistent with the changes in delta-theta neural oscillations, suggesting the involvement of cortical tracking of speech envelopes. The study thus provides neurophysiological evidence for goal-oriented modulation of attended speech and calls for speech perception models incorporating limited memory capacity and goal-oriented optimization mechanisms.

The Roles of Consonant, Rime, and Tone in Mandarin Spoken Word Recognition: An Eye-Tracking Study

This study investigated the relative role of sub-syllabic components (initial consonant, rime, and tone) in spoken word recognition of Mandarin Chinese using an eye-tracking experiment with a visual world paradigm. Native Mandarin speakers (all born and grew up in Beijing) were presented with four pictures and an auditory stimulus. They were required to click the picture according to the sound stimulus they heard, and their eye movements were tracked during this process. For a target word (e.g., tang2 "candy"), nine conditions of competitors were constructed in terms of the amount of their phonological overlap with the target: consonant competitor (e.g., ti1 "ladder"), rime competitor (e.g., lang4 "wave"), tone competitor (e.g., niu2 "cow"), consonant plus rime competitor (e.g., tang1"soup"), consonant plus tone competitor (e.g., tou2 "head"), rime plus tone competitor (e.g., yang2 "sheep"), cohort competitor (e.g., ta3 "tower"), cohort plus tone competitor (e.g., tao2 "peach"), and baseline competitor (e.g., xue3 "snow"). A growth curve analysis was conducted with the fixation to competitors, targets, and distractors, and the results showed that (1) competitors with consonant or rime overlap can be adequately activated, while tone overlap plays a weaker role since additional tonal information can strengthen the competitive effect only when it was added to a candidate that already bears much phonological similarity with the target. (2) Mandarin words are processed in an incremental way in the time course of word recognition since different partially overlapping competitors could be activated immediately; (3) like the pattern found in English, both cohort and rime competitors were activated to compete for lexical activation, but these two competitors were not temporally distinctive and mainly differed in the size of their competitive effects. Generally, the gradation of activation based on the phonological similarity between target and candidates found in this study was in line with the continuous mapping models and may reflect a strategy of native speakers shaped by the informative characteristics of the interaction among different sub-syllabic components.