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The mirror is not enough: The case of complementary actions [Quando il mirror non basta. Il caso delle azioni complementari]
No full textHuman beings come into the world wired for social interaction. As has been observed in mimicry, priming, and automatic imitation, indeed, humans are remarkably efficient at resonating with one another. In specific contexts that require incongruent, complementary (from Latin complemèntum; i.e., that fills up) rather than imitative forms of interaction, nevertheless, motor resonance with the observed action can be an unsuitable response. In the case, for example, that someone hands us a mug by its handle with a precision grip, we will automatically, without thinking, grab the mug using a whole-hand-grasp (the most suitable grasping gesture in this particular situation). The types of grasps adopted by the two interacting agents are incongruent, but functionally appropriate. This example illustrates the importance of complementary actions in the context of the action–perception domain, and it encourages us to take a look at what is taking place behind the scenes and to question the mechanisms classically thought to be involved in motor resonant responses (e.g., the mirror system). In this article I shall review recent data unveiling this aspect, which have increased our knowledge on the flexibility of the human motor system in social contexts
Acting Social Intentions
Full text linkAre intentions – and social intention, in particular – translated into motor patterns?
The present thesis provides an attempt to indagate interactive minds and the mechanisms underlying such phenomenon from a behavioural perspective, by adopting a motor control approach.
Our findings suggest that prior social intentions translate into specific motor pattern and provide evidence for the existence of differences in motor patterning depending on social context and intentions (social vs. individual, communicative vs. non communicative, cooperative vs. competitive). These differences, we surmise, may be used by the observer’s motor system to discriminate between actions serving different intentions. Prejudice biases as well have proved to influence the planning control system. As we demonstrated, ‘gender-driven’ prior intentions are reflected in the kinematics. In the last series of experiment we tested the effects of sudden social requests on the online control of action. These data suggest for the first time that the exposure to a sudden social request produces reliable changes on the action on-line control system.Le intenzioni – proprie e altrui – vengono codificate nell’atto motorio? La presente tesi costituisce un tentativo di indagare in quali modalità avvenga la traduzione delle intenzioni sociali in specifici pattern motori. Il dato emerso dai primi esperimenti è che le intenzioni sociali si riflettono direttamente nella cinematica: specifici pattern motori distinguono azioni sociali da azioni individuali e tali differenze possono essere usate da chi le osserva per discriminarle, risalendo così alle intenzioni dell’agente. Non solo, ma come abbiamo dimostrato in un successivo esperimento, cooperare con un partner che esibisce inaspettatamente l’intenzione di competere rende l’azione del soggetto molto più competitiva, e viceversa. L’intenzione del partner, quindi, modula la pianificazione e l’esecuzione delle azioni di chi vi interagisce e la cinematica del movimento è in seguito risultata sensibile anche agli stereotipi sul sesso. Scopo dell’ultima serie di studi era indagare come il sistema motorio gestisce le interazioni sociali inaspettate e implementa nuovi piani di azione per portare a termine l’esecuzione del movimento. Improvvise richieste sociali veicolate da un agente umano sembrano essere in grado di influenzare pattern motori precedentemente pianificati attraverso un monitoraggio on-line delle azioni altrui
Complementary Actions
Full text linkHuman beings come into the world wired for social interaction. At the fourteenth week of gestation, twin fetuses already display interactive movements specifically directed towards their co- twin. Readiness for social interaction is also clearly expressed by the newborn who imitate facial gestures, suggesting that there is a common representation mediating action observation and execution. While actions that are observed and those that are planned seem to be functionally equivalent, it is unclear if the visual representation of an observed action inevitably leads to its motor representation. This is particularly true with regard to complementary actions (from the Latin complementum ; i.e. that fills up), a specific class of movements which differ, while interacting, with observed ones. In geometry, angles are defined as complementary if they form a right angle. In art and design, complementary colors are color pairs that, when combined in the right proportions, produce white or black. As a working definition, complementary actions refer here to any form of social interaction
wherein two (or more) individuals complete each other’s actions in a balanced way. Successful complementary interactions are founded on the abilities: (1) to simulate another person’s movements; (2) to predict another person’s future action/ s; (3) to produce an appropriate congruent/ incongruent response that completes the other person’s action/ s; and (4) to integrate the predicted effects of one’s own and another person’s actions. It is the neurophysiological mechanism that underlies this process which forms the main theme of this chapte
Shadows in the mirror
Full text linkMirror neurons are a class of visuo-motor neurons activated by both the execution and passive observation of object-related actions. Evidence for the existence of mirror neurons in the human brain comes in part from transcranial magnetic stimulation studies showing that observation of an action causes subliminal activation of corresponding corticospinal pathways within the motor system. During daylight and lighted conditions movement is nearly always preceded, accompanied, and followed by shadows. Shadows that are cast as someone observes a biological movement could potentially provide information for action recognition. The objective of this study was to assess the mirror system's ability to resonate with shadowed movements. Primary motor cortex excitability was evaluated here by motor-evoked potentials elicited during single-pulse transcranial magnetic stimulation and recorded from two hand muscles as participants observed a prehensile action performed in two illumination conditions: one in which the observed action was fully illuminated and one in which a moving body part was partially shadowed. It will be shown that overall modulation of the primary motor cortex excitability during action observation is significantly lower for the shadowed with respect to the fully illuminated condition. Processing shadows determines a modulation of corticospinal excitability, suggesting that the mirror system is finely tuned to that visual aspect of biological movements
Incontri prenatali. I feti gemelli e la genesi dell'interazione sociale
Full text linkSaper interagire con gli altri è uno dei presupposti delle nostre abilità sociali. Non ci sarebbe apprendimento né un adeguato adattamento all’ambiente in cui viviamo senza interazioni e scambi reciproci di informazioni.
Secondo un’analogia diffusa tra cervello biologico e artificiale, esisterebbe una sorta di wiring – un circuito – alla base della propensione umana per le interazioni sociali. Nasciamo già corredati di un meccanismo che ci predispone a tale tipo di interazioni. Fin dai primi giorni di vita, infatti, i neonati si sforzano di imitare alcune espressioni facciali di chi si prende cura di loro (Meltzoff et al., 1983; 1989). Ma tale propensione è già presente prima della nascita o si acquisisce con le prime esperienze post parto? Questa stimolante domanda ci ha indotti a condurre uno studio evolutivo sui feti gemelli, che condividono per mesi l’utero materno (Castiello et al., 2010). Un’opportunità unica e preziosa, questa, per studiare la genesi e l’evolversi di un possibile meccanismo pro-sociale.
Se l’evoluzione di un tale meccanismo precede la nascita, allora dovremmo trovarne traccia nei feti gemelli, laddove esistono i presupposti per un’azione sociale, ovvero rivolta verso un altro individuo. Alcuni studi sui feti singoli hanno messo in luce l’esistenza di prime forme di pianificazione del movimento a 22 settimane di gestazione (Zoia et al., 2007). Ad oggi, però, nessuno studio aveva indagato l’esistenza di movimenti pianificati ed eseguiti nell’utero materno con il preciso scopo di raggiungere e toccare il proprio gemello. E il termine “pianificati” non è casuale. Sta ad indicare la peculiarità di tali gesti, che si differenziano dai meri riflessi e si avvicinano invece al concetto di “azioni”. Mentre i riflessi sono comunemente noti per essere del tutto automatici, fissi e fuori dal nostro controllo volontario, le azioni sono intese come movimenti coordinati e diretti a uno scopo, con vari gradi di intenzionalità.
Come è emerso recentemente in studi su soggetti adulti, le azioni svolte in isolamento si differenziano dalle stesse azioni svolte con intento sociale (Becchio et al., 2010). I risultati, infatti, evidenziano come sia possibile distinguere, dal punto di vista dell’organizzazione del movimento, azioni individuali fini a se stesse, dalle stesse azioni eseguite in ambito sociale, e come la pianificazione delle azioni sia influenzata dal contesto sociale (si veda, a tal proposito, quanto descritto nel Box riportato a pagina seguente “Il lato sociale delle azioni”)
Attention in (Joint) Action
No full textObserving actions performed by others can activate the corresponding motor representations in the primary motor cortex (M1), the so-called direct matching. However, it has been proved that in interactive social contexts this imitative tendency could turn into readiness to perform a dissimilar complementary action. To date, whether or not the observation-execution transformation is automatic (i.e. occurs without attention) is debated. In the present study we aim to bring an increase in the literature by assessing the role of spatial attention during observation of social and non social actions. The stimuli used were action sequences eliciting (or not) complementary responses (i.e. incongruent to the observed action) and spatial attention was manipulated by means of a red dot cue. First, eye-tracking procedures were used to measure the spontaneous allocation of overt spatial attention during action observation. Second, we combined transcranial magnetic stimulation (TMS) over M1 and electromyography recordings to assess the excitability of corticospinal projections to hand muscles while participants were observing the action stimuli. Results show that the allocation of spatial attention towards an observed body part is crucial for direct matching to occur. Conversely, the allocation of spatial attention plays no role when the observed action evokes an interactive complementary motor response. Overall, the present research provides one of the first evidence that social motor preparation is impervious to spatial attentional allocation
Motor cortex excitability is tightly coupled to observed movements
No full textAlthoughfacilitationofthecorticospinal(CS)systemduringactionobservationisawidelyaccepted
phenomenon,itisstillcontroversialiffacilitationreflectsthereplicaofobservedmovementkinematics
or thetensiontoachieveaparticulargoal.Inthisstudy,transcranialmagneticstimulation(TMS)-
inducedmotorevokedpotentials(MEPs)wererecordedfromtheabductordigitiminimi(ADM)andthe
first dorsalinterosseus(FDI)muscleswhileparticipant–volunteersobservedamodelgraspingasmall
target elicitingaprecisiongriporalargetargetelicitingawholehandgraspdirectedtowardanisolated
object orflankedbydifferentsizedobjects(i.e.,distractor).Adetailedmovementanalysisrevealedthat
the model’skinematicswereinfluencedbythedistractor’ssize.Videoclipsfilmingthescenewere
edited insuchawaythatthedistractorwasremovedfromthescene.Participant–volunteerswere
asked toobserveactionscharacterizedbythesamegoalbutperformedusingdifferentkinematical
patterns.Althoughthedifferencesinmovementkinematicswerenotnoticedbytheparticipant-
volunteers,theynonethelesseliciteddistinctconfigurationsofcorticospinalactivation.Detailedmotor
matchingseemstorecruitthesamemusclesintheonlookerasinthepersonactuallycarryingoutthe
action duringobservationofgraspingactions.Theseeffectsappeartobeelicitedbyverysubtle,
imperceptibleaspectsofobservedactionspointingtoafinelytunedmechanismthatspecifically
encodesbodyparts
The role of spatial attention during action observation: the case of complementary actions
No full textBackground: Interactive social contexts often require to perform actions dissimilar to those observed (i.e., complementary actions). To date, the role of attention in this endeavor is still unexplored.
Methods: In the present research we aimed to study the role of spatial attention during action observation. The stimuli used were action sequences eliciting (or not) complementary responses in the participant’s hand. Spatial attention was manipulated by means of a red dot cue superimposed on the video clips. First, eye-tracking procedures were used to measure the spontaneous allocation of overt spatial attention during action observation. Second, we recorded motor-evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) to assess the excitability of corticospinal projections to hand muscles while participants were observing the action stimuli.
Results: Results showed that the allocation of spatial attention plays no role when the observed action evokes an interactive complementary motor response. Overall, the present research provides one of the first evidence that social motor preparation is impervious to spatial attentional allocation
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