Can we decode phonetic features in inner speech using surface electromyography?

Words as social tools (WAT): A reprise

The paper presents new evidence collected in the last five years supporting the Words As social Tools proposal on abstract concepts. We discuss findings revolving around three central tenets. First, we show that-like concrete concepts-also abstract concepts evoke sensorimotor experiences, even if to a lower extent, and that they are linked to inner experiences (e.g., interoceptive, proprioceptive, and metacognitive). Second, we present findings suggesting that linguistic and social interaction are crucial for acquiring and using abstract concepts. Specifically, rating and behavioral studies reveal that people tend to feel uncertain about the meaning of abstract concepts. On top of that, with abstract concepts, people rely more on others to ask for information, negotiate conceptual meaning, or outsource their knowledge. We propose that inner speech might contribute both to the monitoring process and the preparation to interact with others. Finally, we illustrate recent studies conducted in our lab highlighting abstract concepts variability across individuals (age, expertise), cultures, and languages.

BCI-controlled wheelchairs: end-users' perceptions, needs, and expectations, an interview-based study

PURPOSE

Brain-computer interface (BCI)-controlled wheelchairs have the potential to improve the independence of people with mobility impairments. The low uptake of BCI devices has been linked to a lack of knowledge among researchers of the needs of end-users that should influence BCI development.

MATERIALS AND METHODS

This study used semi-structured interviews to learn about the perceptions, needs, and expectations of spinal cord injury (SCI) patients with regards to a BCI-controlled wheelchair. Topics discussed in the interview include: paradigms, shared control, safety, robustness, channel selection, hardware, and experimental design. The interviews were recorded and then transcribed. Analysis was carried out using coding based on grounded theory principles.

RESULTS

The majority of participants had a positive view of BCI-controlled wheelchair technology and were willing to use the technology. Core issues were raised regarding safety, cost and aesthetics. Interview discussions were linked to state-of-the-art BCI technology. The results challenge the current reliance of researchers on the motor-imagery paradigm by suggesting end-users expect highly intuitive paradigms. There also needs to be a stronger focus on obstacle avoidance and safety features in BCI wheelchairs. Finally, the development of control approaches that can be personalized for individual users may be instrumental for widespread adoption of these devices.

CONCLUSIONS

This study, based on interviews with SCI patients, indicates that BCI-controlled wheelchairs are a promising assistive technology that would be well received by end-users. Recommendations for a more person-centered design of BCI controlled wheelchairs are made and clear avenues for future research are identified.

Internal speech is faster than external speech: Evidence for feedback-based temporal control

A recent model of temporal control in speech holds that speakers use sensory feedback to control speech rate and articulatory timing. An experiment was conducted to assess whether there is evidence in support of this hypothesis by comparing durations of phrases in external speech (with sensory feedback) and internal speech (without sensory feedback). Phrase lengths were varied by including one to three disyllabic nouns in a target phrase that was always surrounded by overt speech. An inferred duration method was used to estimate the durations of target phrases produced internally. The results showed that internal speech is faster than external speech, supporting the hypothesis. In addition, the results indicate that there is a slow-down associated with transitioning between internal and external modes of production.

Inner speech as language process and cognitive tool

Many people report a form of internal language known as inner speech (IS). This review examines recent growth of research interest in the phenomenon, which has broadly supported a theoretical model in which IS is a functional language process that can confer benefits for cognition in a range of domains. A key insight to have emerged in recent years is that IS is an embodied experience characterized by varied subjective qualities, which can be usefully modeled in artificial systems and whose neural signals have the potential to be decoded through advancing brain-computer interface technologies. Challenges for future research include understanding individual differences in IS and mapping form to function across IS subtypes.

Concepts, abstractness and inner speech

We explore the role of inner speech (covert self-directed talk) during the acquisition and use of concepts differing in abstractness. Following Vygotsky, inner speech results from the internalization of linguistically mediated interactions that regulate cognition and behaviour. When we acquire and process abstract concepts, uncertainties about word meaning might lead us to search actively for their meaning. Inner speech might play a role in this searching process and be differentially involved in concept learning compared with use of known concepts. Importantly, inner speech comes in different varieties-e.g. it can be expanded or condensed (with the latter involving syntactic and semantic forms of abbreviation). Do we use inner speech differently with concepts varying in abstractness? Which kinds of inner speech do we preferentially use with different kinds of abstract concepts (e.g. emotions versus numbers)? What other features of inner speech, such as dialogicality, might facilitate our use of concepts varying in abstractness (by allowing us to monitor the limits of our knowledge in simulated social exchanges, through a process we term inner social metacognition)? In tackling these questions, we address the possibility that different varieties of inner speech are flexibly used during the acquisition of concepts and their everyday use. This article is part of the theme issue 'Concepts in interaction: social engagement and inner experiences'.

Imagined speech increases the hemodynamic response and functional connectivity of the dorsal motor cortex

Objective. Decoding imagined speech from brain signals could provide a more natural, user-friendly way for developing the next generation of the brain-computer interface (BCI). With the advantages of non-invasive, portable, relatively high spatial resolution and insensitivity to motion artifacts, the functional near-infrared spectroscopy (fNIRS) shows great potential for developing the non-invasive speech BCI. However, there is a lack of fNIRS evidence in uncovering the neural mechanism of imagined speech. Our goal is to investigate the specific brain regions and the corresponding cortico-cortical functional connectivity features during imagined speech with fNIRS.Approach. fNIRS signals were recorded from 13 subjects' bilateral motor and prefrontal cortex during overtly and covertly repeating words. Cortical activation was determined through the mean oxygen-hemoglobin concentration changes, and functional connectivity was calculated by Pearson's correlation coefficient.Main results. (a) The bilateral dorsal motor cortex was significantly activated during the covert speech, whereas the bilateral ventral motor cortex was significantly activated during the overt speech. (b) As a subregion of the motor cortex, sensorimotor cortex (SMC) showed a dominant dorsal response to covert speech condition, whereas a dominant ventral response to overt speech condition. (c) Broca's area was deactivated during the covert speech but activated during the overt speech. (d) Compared to overt speech, dorsal SMC(dSMC)-related functional connections were enhanced during the covert speech.Significance. We provide fNIRS evidence for the involvement of dSMC in speech imagery. dSMC is the speech imagery network's key hub and is probably involved in the sensorimotor information processing during the covert speech. This study could inspire the BCI community to focus on the potential contribution of dSMC during speech imagery.

Dissociating facial electromyographic correlates of visual and verbal induced rumination

Previous research showed that mental rumination, considered as a form of repetitive and negative inner speech, is associated with increased facial muscular activity. However, the relation between these muscular activations and the underlying mental processes is still unclear. In this study, we tried to separate the facial electromyographic correlates of induced rumination related to either i) mechanisms of (inner) speech production or ii) rumination as a state of pondering on negative affects. To this end, we compared two groups of participants submitted to two types of rumination induction (for a total of 85 female undergraduate students without excessive depressive symptoms). The first type of induction was designed to specifically induce rumination in a verbal modality whereas the second one was designed to induce rumination in a visual modality. Following the motor simulation view of inner speech production, we hypothesised that the verbal rumination induction should result in a higher increase of activity in the speech-related muscles as compared to the non-verbal rumination induction. We also hypothesised that relaxation focused on the orofacial area should be more efficient in reducing rumination (when experienced in a verbal modality) than a relaxation focused on a non-orofacial area. Our results do not corroborate these hypotheses, as both rumination inductions resulted in a similar increase of peripheral muscular activity in comparison to baseline levels. Moreover, the two relaxation types were similarly efficient in reducing rumination, whatever the rumination induction. We discuss these results in relation to the inner speech literature and suggest that because rumination is a habitual and automatic form of emotion regulation, it might be a particularly (strongly) internalised and condensed form of inner speech. Pre-registered protocol, preprint, data, as well as reproducible code and figures are available at: https://osf.io/c9pag/.