Bilingualism augments memory advantage of accent congruency in word recognition.

Potential differences in word and speaker recognition, among monolinguals versus bilinguals, were investigated. Participants heard English words spoken by a male or female with a native Canadian English accent or a Chinese accent at study. Then, participants performed an old/new word recognition test with new words and half of the study words. Last, participants performed a same/different voice recognition test with the other half of the study words. Voice congruency varied so that each trial represented a same-talker, same-accent/different-gender, different-accent/same-gender, or different-accent/different-gender condition. Results indicated a word recognition benefit of accent congruency for participants fluent in the primary language of the talker. This finding suggests that familiarity with accent provides a benefit in verbal memory. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Speaker's voice as a memory cue.

Speaker's voice occupies a central role as the cornerstone of auditory social interaction. Here, we review the evidence suggesting that speaker's voice constitutes an integral context cue in auditory memory. Investigation into the nature of voice representation as a memory cue is essential to understanding auditory memory and the neural correlates which underlie it. Evidence from behavioral and electrophysiological studies suggest that while specific voice reinstatement (i.e., same speaker) often appears to facilitate word memory even without attention to voice at study, the presence of a partial benefit of similar voices between study and test is less clear. In terms of explicit memory experiments utilizing unfamiliar voices, encoding methods appear to play a pivotal role. Voice congruency effects have been found when voice is specifically attended at study (i.e., when relatively shallow, perceptual encoding takes place). These behavioral findings coincide with neural indices of memory performance such as the parietal old/new recollection effect and the late right frontal effect. The former distinguishes between correctly identified old words and correctly identified new words, and reflects voice congruency only when voice is attended at study. Characterization of the latter likely depends upon voice memory, rather than word memory. There is also evidence to suggest that voice effects can be found in implicit memory paradigms. However, the presence of voice effects appears to depend greatly on the task employed. Using a word identification task, perceptual similarity between study and test conditions is, like for explicit memory tests, crucial. In addition, the type of noise employed appears to have a differential effect. While voice effects have been observed when white noise is used at both study and test, using multi-talker babble does not confer the same results. In terms of neuroimaging research modulations, characterization of an implicit memory effect reflective of voice congruency is currently lacking.

Voice reinstatement modulates neural indices of continuous word recognition.

The present study was designed to examine listeners' ability to use voice information incidentally during spoken word recognition. We recorded event-related brain potentials (ERPs) during a continuous recognition paradigm in which participants indicated on each trial whether the spoken word was "new" or "old." Old items were presented at 2, 8 or 16 words following the first presentation. Context congruency was manipulated by having the same word repeated by either the same speaker or a different speaker. The different speaker could share the gender, accent or neither feature with the word presented the first time. Participants' accuracy was greatest when the old word was spoken by the same speaker than by a different speaker. In addition, accuracy decreased with increasing lag. The correct identification of old words was accompanied by an enhanced late positivity over parietal sites, with no difference found between voice congruency conditions. In contrast, an earlier voice reinstatement effect was observed over frontal sites, an index of priming that preceded recollection in this task. Our results provide further evidence that acoustic and semantic information are integrated into a unified trace and that acoustic information facilitates spoken word recollection.

Voice congruency facilitates word recognition.

Behavioral studies of spoken word memory have shown that context congruency facilitates both word and source recognition, though the level at which context exerts its influence remains equivocal. We measured event-related potentials (ERPs) while participants performed both types of recognition task with words spoken in four voices. Two voice parameters (i.e., gender and accent) varied between speakers, with the possibility that none, one or two of these parameters was congruent between study and test. Results indicated that reinstating the study voice at test facilitated both word and source recognition, compared to similar or no context congruency at test. Behavioral effects were paralleled by two ERP modulations. First, in the word recognition test, the left parietal old/new effect showed a positive deflection reflective of context congruency between study and test words. Namely, the same speaker condition provided the most positive deflection of all correctly identified old words. In the source recognition test, a right frontal positivity was found for the same speaker condition compared to the different speaker conditions, regardless of response success. Taken together, the results of this study suggest that the benefit of context congruency is reflected behaviorally and in ERP modulations traditionally associated with recognition memory.

Auditory evoked potentials dissociate rapid perceptual learning from task repetition without learning.

Performance improvement during an hour of auditory perceptual training is accompanied by rapid physiological changes. These changes may reflect learning or simply task repetition independent of learning. We assessed the contribution of learning and task repetition to changes in auditory evoked potentials during a difficult speech identification task and an easy tone identification task. We posited that only task repetition effects would occur in the tone task but that task repetition and learning would interact in the speech task. Speech identification improved with practice (increased sensitivity d' with a constant response bias ß). This behavioral improvement coincided with a decrease in the amplitude of sensory evoked responses (N1, P2) and a decrease in the amplitude of a slow wave (peak=320 ms after onset) over the left frontal and parietal sites. Results show rapid physiological changes associated with learning, distinct from changes related to task repetition.

Changes in sensory evoked responses coincide with rapid improvement in speech identification performance.

Perceptual learning is sometimes characterized by rapid improvements in performance within the first hour of training (fast perceptual learning), which may be accompanied by changes in sensory and/or response pathways. Here, we report rapid physiological changes in the human auditory system that coincide with learning during a 1-hour test session in which participants learned to identify two consonant vowel syllables that differed in voice onset time. Within each block of trials, listeners were also presented with a broadband noise control stimulus to determine whether changes in auditory evoked potentials were specific to the trained speech cue. The ability to identify the speech sounds improved from the first to the fourth block of trials and remained relatively constant thereafter. This behavioral improvement coincided with a decrease in N1 and P2 amplitude, and these learning-related changes differed from those observed for the noise stimulus. These training-induced changes in sensory evoked responses were followed by an increased negative peak (between 275 and 330 msec) over fronto-central sites and by an increase in sustained activity over the parietal regions. Although the former was also observed for the noise stimulus, the latter was specific to the speech sounds. The results are consistent with a top-down nonspecific attention effect on neural activity during learning as well as a more learning-specific modulation, which is coincident with behavioral improvements in speech identification.