What Do Second Language Listeners Know About Spoken Words? Effects of Experience and Attention in Spoken Word Processing

With a goal of investigating psycholinguistic bases of spoken word processing in a second language (L2), this study examined L2 learners' sensitivity to phonological information in spoken L2 words as a function of their L2 experience and attentional demands of a learning task. Fifty-two Chinese learners of English who differed in amount of L2 experience (longer vs. shorter residence in L2 environment) were tested in an auditory word priming experiment on well-known L2 words under two processing orientation conditions (semantic, control). Results revealed that, with more L2 experience, learners become more sensitive to phonological detail in spoken L2 words but that attention to word meaning might eliminate this sensitivity, even for learners with more L2 experience.     

Nicotinic modulation of tone-evoked responses in auditory cortex reflects the strength of prior auditory learning

Nicotinic acetylcholine receptors (nAChRs) contribute to sensory-cognitive function, as demonstrated by evidence that nAChR activation enhances, and nAChR blockade impairs, neural processing of sensory stimuli and sensory-cognitive behavior. To better understand the relationship between nAChR function and behavior, here we compare the strength of nAChR-mediated physiology in individual animals to their prior auditory behavioral performance. Adult rats were trained on an auditory-cued, active avoidance task over 4 days and classified as “good,” “intermediate” or “poor” performers based on their initial rate of learning and eventual level of performance. Animals were then anesthetized, and tone-evoked local field potentials (LFPs) recorded in layer 4 of auditory cortex (ACx) before and after a test dose of nicotine (0.7 mg/kg, s.c.) or saline. In “good” performers, nicotine enhanced LFP amplitude and decreased response threshold to characteristic frequency (CF) stimuli, yet had opposite effects (decreased amplitude, increased threshold) on responses to spectrally distant stimuli; i.e., cortical receptive fields became more selective for CF stimuli. In contrast, nicotine had little effect on LFP amplitude in “intermediate” or “poor” performing animals. Nicotine did, however, reduce LFP onset latency in all three groups, indicating that all received an effective dose of the drug. Our findings suggest that nicotinic regulation of cortical receptive fields may be a distinguishing feature of the best-performing animals, and may facilitate sensory-related learning by enhancing receptive field selectivity.     

Motivationally neutral stimulation of the nucleus basalis induces specific behavioral memory

The cholinergic system has been implicated in learning and memory. The nucleus basalis (NB) provides acetylcholine (ACh) to the cerebral cortex. Pairing a tone with NB stimulation (NBstm) to alter cortical state induces both associative specific tuning plasticity in the primary auditory cortex (A1) and associative specific auditory behavioral memory. NB-induced memory has major features of natural memory that is induced by pairing a tone with motivational reinforcers, e.g., food or shock, suggesting that the cholinergic system may be a “final common pathway” whose activation promotes memory storage. Alternatively, NB stimulation might itself be motivationally significant, either rewarding or punishing. To investigate these alternatives, adult male rats (n = 7) first formed a specific NB-induced memory (CS = 8.0 kHz, 2.0 s paired with NBstm, ISI = 1.8 s, 200 trials), validated by post-training (24 h) frequency generalization gradients (1–15 kHz) of respiration interruption that were specific to the CS frequency. Thereafter, they received the same level of NBstm that had induced memory, while confined to one quadrant of an arena, and later tested for place-preference, i.e., avoidance or seeking of the quadrant of NBstm. This NBstm group exhibited neither preference for nor against the stimulated quadrant, compared to sham-operated subjects (n = 7). The findings indicate that specific associative memory can be induced by direct activation of the NB without detectable motivational effects of NB stimulation. These results are concordant with a memory-promoting role for the nucleus basalis that places it “downstream” of motivational systems, which activate it to initiate the storage of the current state of its cholinergic targets.     

Empirical evaluation of a model of global psychophysical judgments: III. A form for the psychophysical function and intensity filtering

In part I, a concept of ratio estimation is defined and it is shown that if such estimates depend only upon the physical ratio of the signal to the reference signal, the psychophysical function must be a power function. Assuming the same exponents for each component, an invariance condition, equivalent to a sum of power functions, is studied empirically for binaural loudness. It is fully or partially sustained for 19 of 22 respondents. Since failures may be attributable to different exponents in the two ears, the ratio of the two exponents is estimated but that fails to explain the failures. Other possible explanations are suggested. In part II, an intensity filtering model is presented, accounting for the phenomenon where monaural loudness matches show a bias depending on the matching ear. We show (a) that the existence of such a bias does not alter the prior experimental results; and (b) assuming the power function, that five respondents attenuate the opposite ear and two enhance it.     

The chronometry of mental ability: An event-related potential analysis of an auditory oddball discrimination task

The relation between intelligence and speed of auditory discrimination was investigated during an auditory oddball task with backward masking. In target discrimination conditions that varied in the interval between the target and the masking stimuli and in the tonal frequency of the target and masking stimuli, higher ability participants (HA) displayed more accurate discriminations, faster response time, larger P300 amplitude, and shorter P300 and mismatch negativity (MMN) latency than lower ability participants (LA). Task difficulty effects demonstrated with variation in mask type indicate that the mask does not interfere with the detection of the deviant target stimulus, but rather that the target and mask are integrated as a single compound stimulus. The temporal effects suggest that the speed of accessing short-term memory is faster for HA than LA and, on the basis of the MMN latency, the effect is accomplished automatically, without focused attention. Moreover, the pattern of results obtained with these data support the view that the accuracy effects are determined by processing speed rather than discrimination ability. Comparator models that accommodate these effects are discussed.     

Rate and duration memory of naturalistic sounds

Research has shown that the tempi of familiar songs are remarkably well-remembered with a high degree of accuracy. The goal of the present research was to determine whether this ability generalizes to various types of ecological sounds and, if so, how rate information is encoded into the cognitive system. Across three experiments, participants were familiarized with a set of sounds and later asked to remember the rate of each. Experiment 1 revealed that the inherent rate of sounds is incidentally learned such that subsequent recognition is comparable across both prospective and retrospective paradigms. Experiment 2 confirmed these findings through an adjustment task and further demonstrated that memory for event rate remains highly accurate regardless if attending is initially directed toward a sound's rate and/or pitch qualities. Lastly, Experiment 3 assessed the ability to recognize event rate vs. duration when the two dimensions systematically co-vary with one another and revealed that rate variations influence duration recognition but not vice versa. These overall findings are discussed relative to a framework that emphasizes the role of event structure in time judgment behavior.     

The role of auditory context in action-effect-related motor adaptation

Previous research indicates that adding auditory effects to a (silent) action can lead to substantial efficiency gains in the performance of the action, while compromising the connection between the motor and the auditory event (e.g., by removing, or by delaying the auditory effects), leads the agent to compensate for the loss of auditory feedback by executing actions in a way which increases the probability of success or enhances feedback in other modalities, thus departing from the optimal action performance. The current study explored how this motor adaptation was affected when the quality of auditory feedback was reduced by contextual factors, while keeping the physical link between the action and auditory effect intact. In two experiments, participants elicited pure tones by pinching a force sensitive resistor (FSR). In some of the conditions action-effect contingency was reduced by intermixing externally initiated tones with the self-induced ones. Pinch-force measurements indicated that action optimization was affected by contextual factors. The influence of auditory context was the most pronounced when the discrimination of self-induced and external tones was made difficult by the similarity and temporal proximity of the self-induced and external tones. In these conditions, tone eliciting actions were more forceful in comparison to conditions in which no external tones were presented, and in comparison to conditions in which the external tones were easily distinguishable from self-induced ones. This suggests that contextual factors can induce similar motor adjustments as manipulating the physical connection between the action and its sensory consequences.     

ERP Evidence for the Rapid Assignment of an (Appropriate) Antecedent to PRO

Event-related brain potentials were recorded while subjects listened to sentences containing a controlled infinitival complement. Subject and object control items were used, both with 2 potential antecedents in the upper clause. Half of the sentences had a gender agreement violation between the null subject of the infinitival complement and an adjective predicated of it. The rapid detection of this anomaly would indicate that the parser had established the coreference relation between the null subject and an antecedent, and that the processor had rapidly consulted verb control information to select the proper antecedent of the null subject. The results showed that for both subject and object control items ungrammatical adjectives elicited a P600 effect. These data imply that the processor has coindexed the null subject with an antecedent, and that the antecedent has been selected on the basis of control information. These results are compatible with parsing models that emphasize the rapid influence of verb-specific information on sentence processing.     

Auditory joint attention skills: Development and diagnostic differences during infancy

To date, joint attention skill assessments have focused on children’s responses to multimodal bids (RJA) and their initiation of bids (IJA) to multimodal spectacles. Here we gain a systematic view of auditory joint attention skills using a novel assessment that measures both auditory and multimodal RJA and IJA. In Study 1, 47 typically developing (TD) children were tested 5 times from 12 to 30 months to document auditory joint attention skill development. In Study 2, 113 toddlers (39 TD, 33 autism spectrum disorder [ASD], and 41 non-ASD developmental disorders [DD]; average age 22.4 months) were tested to discern the effects of ASD. Our findings fit well within the established depiction of joint attention skills with one important caveat: auditory items were far more difficult to execute than multimodal ones. By 24 months, TD children passed multimodal RJA items at the near-ceiling level, an accomplishment not reached even by 30 months for auditory RJA items. Intentional communicative IJA bids also emerged more slowly to auditory spectacles than to multimodal spectacles. Toddlers with DD outperformed toddlers with ASD on multimodal RJA items but toddlers in both groups rarely passed any auditory RJA items. Toddlers with ASD often monitored their partner’s attention during IJA items, albeit less often than toddlers with DD and TD toddlers, but they essentially never produced higher-level IJA bids, regardless of modality. Future studies should investigate further how variations in bids and targets affect auditory joint attention skills and probe the relation between these skills and language development.