Pure tone discrimination with cochlear implants and filter-band spread

For many cochlear implant (CI) users, frequency discrimination is still challenging. We studied the effect of frequency differences relative to the electrode frequency bands on pure tone discrimination. A single-center, prospective, controlled, psychoacoustic exploratory study was conducted in a tertiary university referral center. Thirty-four patients with Cochlear Ltd. and MED-EL CIs and 19 age-matched normal-hearing control subjects were included. Two sinusoidal tones were presented with varying frequency differences. The reference tone frequency was chosen according to the center frequency of basal or apical electrodes. Discrimination abilities were psychophysically measured in a three-interval, two-alternative, forced-choice procedure (3I-2AFC) for various CI electrodes. Hit rates were measured, particularly with respect to discrimination abilities at the corner frequency of the electrode frequency-bands. The mean rate of correct decision concerning pitch difference was about 60% for CI users and about 90% for the normal-hearing control group. In CI users, the difference limen was two semitones, while normal-hearing participants detected the difference of one semitone. No influence of the corner frequency of the CI electrodes was found. In CI users, pure tone discrimination seems to be independent of tone positions relative to the corner frequency of the electrode frequency-band. Differences of 2 semitones can be distinguished within one electrode.

Energy optimization during walking involves implicit processing

ABSTRACT Gait adaptations, in response to novel environments, devices or changes to the body, can be driven by the continuous optimization of energy expenditure. However, whether energy optimization involves implicit processing (occurring automatically and with minimal cognitive attention), explicit processing (occurring consciously with an attention-demanding strategy) or both in combination remains unclear. Here, we used a dual-task paradigm to probe the contributions of implicit and explicit processes in energy optimization during walking. To create our primary energy optimization task, we used lower-limb exoskeletons to shift people's energetically optimal step frequency to frequencies lower than normally preferred. Our secondary task, designed to draw explicit attention from the optimization task, was an auditory tone discrimination task. We found that adding this secondary task did not prevent energy optimization during walking; participants in our dual-task experiment adapted their step frequency toward the optima by an amount and at a rate similar to participants in our previous single-task experiment. We also found that performance on the tone discrimination task did not worsen when participants were adapting toward energy optima; accuracy scores and reaction times remained unchanged when the exoskeleton altered the energy optimal gaits. Survey responses suggest that dual-task participants were largely unaware of the changes they made to their gait during adaptation, whereas single-task participants were more aware of their gait changes yet did not leverage this explicit awareness to improve gait adaptation. Collectively, our results suggest that energy optimization involves implicit processing, allowing attentional resources to be directed toward other cognitive and motor objectives during walking.

Native language, L2 experience, and pitch processing in music

The current study investigated how the role of pitch in one’s native language and L2 experience influenced musical melodic processing by testing Turkish and Mandarin Chinese advanced and beginning learners of English as an L2. Pitch has a lower functional load and shows a simpler pattern in Turkish than in Chinese as the former only contrasts between presence and the absence of pitch elevation, while the latter makes use of four different pitch contours lexically. Using the Musical Ear Test as the tool, we found that the Chinese listeners outperformed the Turkish listeners, and the advanced L2 learners outperformed the beginning learners. The Turkish listeners were further tested on their discrimination of bisyllabic Chinese lexical tones, and again an L2 advantage was observed. No significant difference was found for working memory between the beginning and advanced L2 learners. These results suggest that richness of tonal inventory of the native language is essential for triggering a music processing advantage, and on top of the tone language advantage, the L2 experience yields a further enhancement. Yet, unlike the tone language advantage that seems to relate to pitch expertise, learning an L2 seems to improve sound discrimination in general, and such improvement exhibits in non-native lexical tone discrimination.

Dissociation of tone merger and congenital amusia in Hong Kong Cantonese

While the issue of individual variation has been widely studied in second language learning or processing, it is less well understood how perceptual and musical aptitude differences can explain individual variation in native speech processing. In the current study, we make use of tone merger in Hong Kong Cantonese, an ongoing sound change that concerns the merging of tones in perception, production or both in a portion of native speakers, to examine the possible relationship between tone merger and musical and pitch abilities. Although a previous study has reported the occurrence of tone merger independently of musical training, it has not been investigated before whether tone-merging individuals, especially those merging tones in perception, would have inferior musical perception and fine-grained pitch sensitivities, given the close relationship of speech and music. To this end, we tested three groups of tone-merging individuals with various tone perception and production profiles on musical perception and pitch threshold tasks, in comparison to a group of Cantonese speakers with congenital amusia, and another group of controls without tone merger or amusia. Additionally, the amusics were compared with tone-merging individuals on the details of their tone discrimination and production profiles. The results showed a clear dissociation of tone merger and amusia, with the tone-merging individuals exhibiting intact musical and pitch abilities; on the other hand, the amusics demonstrated widespread difficulties in tone discrimination yet intact tone production, in contrast to the highly selective confusion of a specific tone pair in production or discrimination in tone-merging individuals. These findings provide the first evidence that tone merger and amusia are distinct from each other, and further suggest that the cause of tone merger may lie elsewhere rather than being driven by musical or pitch deficits. We also discussed issues arising from the current findings regarding the neural mechanisms of tone merger and amusia.

Learning of across- and within-task contingencies modulates partial-repetition costs in dual-tasking

Dual-task costs might result from confusions on the task-set level as both tasks are not represented as distinct task-sets, but rather being integrated into a single task-set. This suggests that events in the two tasks are stored and retrieved together as an integrated memory episode. In a series of three experiments, we tested for such integrated task processing and whether it can be modulated by regularities between the stimuli of the two tasks (across-task contingencies) or by sequential regularities within one of the tasks (within-task contingencies). Building on the experimental approach of feature binding in action control, we tested whether the participants in a dual-tasking experiment will show partial-repetition costs: they should be slower when only the stimulus in one of the two tasks is repeated from Trial n − 1 to Trial n than when the stimuli in both tasks repeat. In all three experiments, the participants processed a visual-manual and an auditory-vocal tone-discrimination task which were always presented concurrently. In Experiment 1, we show that retrieval of Trial n − 1 episodes is stable across practice if the stimulus material is drawn randomly. Across-task contingencies (Experiment 2) and sequential regularities within a task (Experiment 3) can compete with n − 1-based retrieval leading to a reduction of partial-repetition costs with practice. Overall the results suggest that participants do not separate the processing of the two tasks, yet, within-task contingencies might reduce integrated task processing.

Disentangling Doubt and Checking Behaviors and Examining Their Association With Obsessive Compulsive Symptoms

Experiencing doubt in an uncertain situation has been theorized to be an antecedent of compulsive checking. However, whether and when obsessive compulsive (OC) symptoms are associated with experiencing doubt and increased checking is unclear. In this study, we investigated the relationship between OC symptoms, the experience of doubt, and checking in a tone-discrimination task. Doubt was measured using mouse tracking, an indirect, unobtrusive measure. The results of two studies ( N = 119) showed that OC symptoms were associated with elevated experiences of doubt when uncertainty was low. However, OC symptoms were not associated with increased checking, but doubt was. Results highlight the utility of mouse-tracking measures to capture the tendency of individuals with OC symptoms to experience doubt even under neutral conditions. The unexpected null results concerning checking suggest some specific directions for research to determine the conditions under which doubt evolves into checking in obsessive compulsive disorder.

Selection in working memory is resource-demanding: Concurrent task effects on the retro-cue effect

In a retro-cue paradigm, after memorizing a set of objects, people are cued to remember only a subset. Improved memory from the retro-cue suggests that selection processes can benefit items stored in working memory. Does selection in working memory require attention? If so, an attention-demanding task should disrupt retro-cue effects. Studies using a dual-task paradigm have found mixed results, with only one study (Janczyk & Berryhill, Attention, Perception, and Psychophysics, 76 (3), 715–724, 2014) showing a decreased retro-cue effect by a secondary task. Here we explore a potential issue in that study – the temporal overlap of the secondary task response with the memory test presentation. This raises questions about whether the secondary task was impairing selection processes in memory or was impacting the memory response. We replicated their paradigm by inserting a tone discrimination task at the retro-cue offset, but we also included a condition in which the tone task and the memory test were temporally separated. In Experiment 1, performing the tone task did not impair the retro-cue effect. In Experiment 2, we added an articulatory suppression task as in Janczyk and Berryhill’s study, and we found that the requirement to execute the tone task impaired retro-cue effects. This impairment was independent of whether the tone and memory tasks overlapped. These findings suggest that internal prioritization can be impaired by dual-task interference, but may only occur when such interference is robust enough, for example, due to switching between multiple tasks.

Episodic-like memory of rats as retrospective retrieval of incidentally encoded locations and involvement of the retrosplenial cortex

To examine episodic memory in rats, we trained rats to perform two tasks and tested them for memory of past self-behavior without making them expect to be asked about the memory later when encoding. One of the trained tasks was a delayed matching-to-position task in which the rats were required to remember the location of a presented lever. The other was a tone discrimination task in which the rats were required to discriminate between two pure tones. After learning both tasks, the rats were unexpectedly asked the location of the pressed lever after responding to the cue tone in probe trials during test sessions. The rats demonstrated a response bias that suggests that they have the ability to retrospectively recollect their self-behavior, i.e., episodic memory. We next made excitotoxic lesions in the retrosplenial cortex (RSC) and investigated the effects of the lesions on the unexpected recollection. In the rats with lesions of the RSC, the response bias disappeared. This suggests that the RSC has a role in retrospectively answering unexpected questions about self-behavior.