Language for action: Motor resonance during the processing of human and robotic voices

The role of motor inhibition in implicit negation processing: two Go/No-Go behavioral studies

Several studies demonstrated that explicit forms of negation processing (e.g., "I don't know") recruits motor inhibitory mechanisms. However, whether this is also true for implicit negation, in which the negative meaning is implicated but not explicitly lexicalized in the sentence (e.g., "I ignore"), has never been studied before. Two Go/No-Go studies, which differed only for the time-windows to respond to the Go stimulus, were carried out. In each, participants (N = 86 in experiment 1; N = 87 in experiment 2) respond to coloured circle while reading task-irrelevant affirmative, explicit negative and implicit negative sentences. We aimed to investigate whether: (i) the processing of implicit negations recruits inhibitory mechanisms; (ii) these inhibitory resources are differently modulated by implicit and explicit negations. Results show that implicit negative sentences recruit the inhibitory resources more strongly when compared to explicit ones, probably due to their inferential nature, likely requiring deeper processing of the negative meaning. Implicit and inferential meaning (i.e., pragmatic information) are grounded too in the same mechanisms that integrate action with perception. Such findings provide further evidence to the embodied account of language, showing that even abstract aspects, like implicit negation, are grounded in the sensory-motor system, by means of functional link between language and motor activity.

Is motor inhibition involved in the processing of sentential negation? An assessment via the Stop-Signal Task

In the last decades, the embodied approach to cognition and language gained momentum in the scientific debate, leading to evidence in different aspects of language processing. However, while the bodily grounding of concrete concepts seems to be relatively not controversial, abstract aspects, like the negation logical operator, are still today one of the main challenges for this research paradigm. In this framework, the present study has a twofold aim: (1) to assess whether mechanisms for motor inhibition underpin the processing of sentential negation, thus, providing evidence for a bodily grounding of this logic operator, (2) to determine whether the Stop-Signal Task, which has been used to investigate motor inhibition, could represent a good tool to explore this issue. Twenty-three participants were recruited in this experiment. Ten hand-action-related sentences, both in affirmative and negative polarity, were presented on a screen. Participants were instructed to respond as quickly and accurately as possible to the direction of the Go Stimulus (an arrow) and to withhold their response when they heard a sound following the arrow. This paradigm allows estimating the Stop Signal Reaction Time (SSRT), a covert reaction time underlying the inhibitory process. Our results show that the SSRT measured after reading negative sentences are longer than after reading affirmative ones, highlighting the recruitment of inhibitory mechanisms while processing negative sentences. Furthermore, our methodological considerations suggest that the Stop-Signal Task is a good paradigm to assess motor inhibition's role in the processing of sentence negation.

On the Embodiment of Negation in Italian Sign Language: An Approach Based on Multiple Representation Theories

Negation can be considered a shared social action that develops since early infancy with very basic acts of refusals or rejection. Inspired by an approach to the embodiment of concepts known as Multiple Representation Theories (MRT, henceforth), the present paper explores negation as an embodied action that relies on both sensorimotor and linguistic/social information. Despite the different variants, MRT accounts share the basic ideas that both linguistic/social and sensorimotor information concur to the processes of concepts formation and representation and that the balance between these components depends on the kind of concept, the context, or the performed task. In the present research we will apply the MRT framework for exploring negation in Italian sign language (LIS). The nature of negation in LIS has been explored in continuity with the co-speech gesture where negative elements are encoded through differentiated prosodic and gestural strategies across languages. Data have been collected in naturalistic settings that may allow a much wider understanding of negation both in speech and in spoken language with a semi-structured interview. Five LIS participants with age range 30–80 were recruited and interviewed with the aim of understanding the continuity between gesture and sign in negation. Results highlight that negation utterances mirror the functions of rejection, non-existence and denial that have been described in language acquisition both in deaf and hearing children. These different steps of acquisition of negation show a different balance between sensorimotor, linguistic and social information in the construction of negative meaning that the MRT is able to enlighten.

Neural correlates of embodied action language processing: a systematic review and meta-analytic study

The neural correlates of action language processing are still debated within embodied cognition research and little is known about the flexible involvement of modality-specific pre-motor system and multimodal high-level temporo-parietal regions as a function of explicit and implicit tasks. A systematic review and the Activation likelihood estimation (ALE) meta-analyses on functional neuroimaging studies were performed to identify neural correlates of action language processing activated during explicit and implicit tasks. The contrast ALE meta-analysis revealed activation of modality-specific premotor area and inferior frontal areas during explicit action language tasks while a greater activation of posterior temporo-occipital areas emerged for implicit tasks. The conjunction analysis revealed overlap in the temporo-parietal multimodal high-level regions for both types of tasks. Functional specialization of the middle temporal gyrus was found where the more posterior-occipital part resulted activated during implicit action language tasks whereas the antero-lateral part was involved in explicit tasks. Our findings were discussed within a conceptual flexibility perspective about the involvement of both the modality-specific and multimodal brain system during action language processing depending on different types of tasks.

Communicative And Affective Components in Processing Auditory Vitality Forms: An fMRI Study

In previous studies on auditory vitality forms, we found that listening to action verbs pronounced gently or rudely, produced, relative to a neutral robotic voice, activation of the dorso-central insula. One might wonder whether this insular activation depends on the conjunction of action verbs and auditory vitality forms, or whether auditory vitality forms are sufficient per se to activate the insula. To solve this issue, we presented words not related to actions such as concrete nouns (e.g.,“ball”), pronounced gently or rudely. No activation of the dorso-central insula was found. As a further step, we examined whether interjections, i.e., speech stimuli conveying communicative intention (e.g., “hello”), pronounced with different vitality forms, would be able to activate, relative to control, the insula. The results showed that stimuli conveying a communicative intention, pronounced with different auditory vitality forms activate the dorsal-central insula. These data deepen our understanding of the vitality forms processing, showing that insular activation is not specific to action verbs, but can be also activated by speech acts conveying communicative intention such as interjections. These findings also show the intrinsic social nature of vitality forms because activation of the insula was not observed in the absence of a communicative intention.

The neural bases of tactile vitality forms and their modulation by social context

People communicate using speech, gestures, and, less frequently, touches. An example of tactile communication is represented by handshake. Customs surrounding handshake vary in different cultures. In Western societies is mostly used when meeting, parting, as a sign of congratulations or at the end of a successful business. Despite its importance in social life, the neural mechanism underlying the affective components conveyed by handshake ("tactile vitality forms") is unknown. Here we combined functional magnetic resonance imaging (fMRI) and electromyography (EMG), to investigate the neural affective activations during handshakes. We demonstrated that handshake conveying gentle or aggressive tactile vitality forms produces a stronger activation of the dorso-central insula. The simultaneous presence of emotional facial expressions modulates the activation of this insular sector. Finally, we provide evidence that the cingulate cortex is involved in the processing of facial expressions conveying different vitality forms.

How attitudes generated by humanoid robots shape human brain activity

During interpersonal interactions, people perform actions with different forms of vitality, communicating their positive or negative attitude toward others. For example, a handshake can be "soft" or "vigorous", a caress can be 'kind' or 'rushed'. While previous studies have shown that the dorso-central insula is a key area for the processing of human vitality forms, there is no information on the perception of vitality forms generated by a humanoid robot. In this study, two fMRI experiments were conducted in order to investigate whether and how the observation of actions generated by a humanoid robot (iCub) with low and fast velocities (Study 1) or replicating gentle and rude human forms (Study 2) may convey vitality forms eliciting the activation of the dorso-central insula. These studies showed that the observation of robotic actions, generated with low and high velocities, resulted in activation of the parieto-frontal circuit typically involved in the recognition and the execution of human actions but not of the insula (Study 1). Most interestingly, the observation of robotic actions, generated by replicating gentle and rude human vitality forms, produced a BOLD signal increase in the dorso-central insula (Study 2). In conclusion, these data highlight the selective role of dorso-central insula in the processing of vitality forms opening future perspectives on the perception and understanding of actions performed by humanoid robots.

Action verb processing specifically modulates motor behaviour and sensorimotor neuronal oscillations

Understanding action-related language recruits the brain’s motor system and can interact with motor behaviour. The current study shows MEG oscillatory patterns during verb-motor priming. Hand and foot verbs were followed by hand or foot responses, with faster reaction times for congruent conditions. In ROIs placed in the hand/arm and foot/leg portions of the sensorimotor cortex, this behavioural priming effect was accompanied by modulations in MEG oscillatory patterns preceding the responses. Power suppression in the alpha/beta frequency bands was reduced in congruent conditions in the body-part-specific ROIs. These results imply that the verb-motor priming effect may be a direct consequence of motor cortex contributions to action word processing.

Neural processing of social interaction: Coordinate-based meta-analytic evidence from human neuroimaging studies

While the action observation and mentalizing networks are considered to play complementary roles in understanding others' goals and intentions, they might be concurrently engaged when processing social interactions. We assessed this hypothesis via three activation-likelihood-estimation meta-analyses of neuroimaging studies on the neural processing of: (a) social interactions, (b) individual actions by the action observation network, and (c) mental states by the mentalizing network. Conjunction analyses and direct comparisons unveiled overlapping and specific regions among the resulting maps. We report quantitative meta-analytic evidence for a "social interaction network" including key nodes of the action observation and mentalizing networks. An action-social interaction-mentalizing gradient of activity along the posterior temporal cortex highlighted a hierarchical processing of interactions, from visuomotor analyses decoding individual and shared intentions to in-depth inferences on actors' intentional states. The medial prefrontal cortex, possibly in conjunction with the amygdala, might provide additional information concerning the affective valence of the interaction. This evidence suggests that the functional architecture underlying the neural processing of interactions involves the joint involvement of the action observation and mentalizing networks. These data might inform the design of rehabilitative treatments for social cognition disorders in pathological conditions, and the assessment of their outcome in randomized controlled trials.

A Peircean account of concepts: grounding abstraction in phylogeny through a comparative neuroscientific perspective

The nature of concepts has always been a hotly debated topic in both philosophy and psychology and, more recently, also in cognitive neuroscience. Different accounts have been proposed of what concepts are. These accounts reflect deeply different conceptions of how the human mind works. In the last decades, two diametrically opposed theories of human cognition have been discussed and empirically investigated: the Computational Theory of Mind, on the one hand (Fodor 1983 The modularity of mind: an essay on faculty psychology; Pylyshyn 1984 Computation and cognition: toward a foundation for cognitive science), and Embodied Cognition (Barsalou 2008 Annu. Rev. Psychol.59, 617-645. (doi:10.1146/annurev.psych.59.103006.093639); Gallese & Lakoff 2005 Cogn. Neuropsychol.22, 455-479 (doi:10.1080/02643290442000310); Shapiro 2011 Embodied cognition), on the other hand. The former proposes that concepts are abstract and amodal symbols in the language of thought, while the latter argues for the embodied nature of concepts that are conceived of as grounded in actions and perception. The embodiment of both concrete and abstract concepts has been challenged by many (e.g. Mahon & Caramazza 2008 J. Physiol.102, 59-70. (doi:10.1016/j.jphysparis.2008.03.004); Caramazza et al 2014 Annu. Rev. Neurosci.37, 1-15. (doi:10.1146/annurev-neuro-071013-013950)). These challenges will be here taken seriously and addressed from a comparative perspective. We will provide a phylogenetic and neurobiologically inspired account of the embodied nature of both abstract and concrete concepts. We will propose that, although differing in certain respect, they both might have a bodily foundation. Commonalities between abstract and concrete concepts will be explained by recurring to the Peircean notions of icon and abductive inference (CP 2.247). According to Peirce, icons are the kind of signs on which abductive inferences rest (Peirce CS 1931 in Collected papers of Charles S. Peirce, Hartshorne C, Weiss P, Burks AW. (eds), 40; Peirce CS 1997 In The 1903 Harvard lectures on pragmatism (ed. A. Turrisi)). It will be claimed that the mechanism of Embodied Simulation (Gallese & Sinigaglia 2011 Trends Cogn. Sci.15, 512-519. (doi:10.1016/j.tics.2011.09.003)) can be described as an icon (Cuccio V & Caruana F. 2015 Il corpo come icona. Abduzione, strumenti ed Embodied Simulation. Versus, n. 119, 93-103), and it will then be suggested that on these, basic natural signs rest, both phylogenetically and ontogenetically, the capacity to conceptualize.This article is part of the theme issue 'Varieties of abstract concepts: development, use and representation in the brain'.

The role of the motor system in action understanding and communication: Evidence from human infants and non-human primates

There is growing evidence that activation of the motor system during observation of actions, a phenomenon first observed in non-human primates, underlies action understanding and even communication. This review (a) examines the evidence on motor system activity as an underlying neural correlate of action understanding; (b) reviews the theoretical and empirical work linking action understanding and the development of communication, with a specific focus on the role that gestures play as an intermediary; and (c) discusses the research on and existing opportunities for understanding the link between the motor system and communication in both humans and non-human primates, through the lens of action perception. Bringing together findings and perspectives from developmental social cognition in both humans and non-human primates and applying recent neuroscientific perspectives will help to elucidate the processes underlying the ability to understand and communicate with others.