Forward effects from action observation: the role of attentional focus.

After viewing an image representing an action on an object, we recognize the forward states of the seen action faster than the backward states. The present study exploits a variant of a new experimental paradigm to investigate cognitive mechanisms underlying this effect. Participants viewed a series of still photos of unfolding actions on objects, each followed by a photo depicting either one of three (instead of two of the original paradigm) different and temporally distant moments after the image or one moment before the image, along with photos of different actions. Experiment 1 revealed the classical forward effects in this new context: when the task was to judge whether the action in the second photo was the same as in the first photo, evaluations were faster for all forward photos than for backward photos. In Experiment 2, we examined the role of participants' attention to the object alongside the role of attention to action kinematics in triggering these "forward effects" by manipulating participants' attentional focus. As the results showed, evaluations were faster for all forward photos when the focus was on the action kinematics, but when the focus was on the object, evaluations were faster only for the last forward photo showing the final action state. These results seem to suggest that focusing on the object triggers a representation of the action goal and thus modulates the mental simulation underlying action anticipation.

Explicit and implicit memory for the QWERTY keyboard: the role of motor simulation and deictic gestures.

In three experiments, we investigated explicit and implicit knowledge about the location of letters on the QWERTY keyboard in young students, and the mechanisms involved. Participants completed a verbal report task in which they were asked to locate the 21 letters of the Italian alphabet on a blank QWERTY keyboard (explicit memory). Subsequently, they carried out a motor production task, i.e., typing letters on a blank keyboard (implicit memory). Consistent with previous studies and several theories emphasizing the importance of implicit knowledge in typing, results showed that explicit knowledge about the QWERTY keyboard is systematically worse than procedural knowledge (Experiment 1). These two types of knowledge, however, are related. Second, we showed that explicit memory for letter position was affected when participants were engaged in a secondary task that required hands/arms movements. Specifically, loading participants' sensorimotor resources led to a decrease in explicit memory performance when the secondary task required hand/arm movements (hand/arms tapping) compared to when it required legs-feet movements (control condition). This result suggests that explicit knowledge is modulated by sensorimotor simulation (Experiment 2). Third, compared to a purely verbal response, pointing to the key on the keyboard did not improve explicit memory accuracy (Experiment 3). Taken together, the results indicate that sensorimotor simulation, and not just gestures, modulates the accessibility to explicit mental representations of verbal/spatial material, like letters on a keyboard.

Action and posture influence the retrieval of memory for objects.

The embodied approach states that memory traces are retrieved, at least in part, through a sensorimotor simulation of the original events, i.e., during retrieval we use our body and its sensorimotor pathways to simulate what happened during encoding. Thus, body manipulations that are incongruent with the motor elements involved at encoding should modulate memory performance. To test this hypothesis, we devised two experiments. In Experiment 1, participants had to observe (observation task) or observe and also perform an action on (enactment task) a series of objects. At recognition, they recognised the enacted objects faster and more accurately than the observed ones. Crucially, in Experiment 2, we manipulated body posture during recognition: one group was asked to hold their hands/arms in front of them (non-interfering group), and the other group was asked to block their hands/arms behind their back (interfering group). The results on reaction times, but not those on accuracy, showed a critical interaction: while the noninterfering group recognised enacted objects faster than observed objects, this advantage disappeared for the interfering group. This suggests that adopting a posture inconsistent with action at encoding could influence the time needed to correctly recognise the objects, but not the accuracy of the recognition.

The implicit effect of action mental simulation on action evaluation.

The main assumption underlying the present investigation is that action observation elicits a mandatory mental simulation representing the action forward in time. In Experiment 1, participants observed pairs of photos portraying the initial and the final still frames of an action video; then they observed a photo depicting the very same action but either forward or backward in time. Their task was to tell whether the action in the photo portrayed something happened before or after the action seen at encoding. In this explicit task, the evaluation was faster for forward photos than for backward photos. Crucially, the effect was replicated when instructions asked only to evaluate at test whether the photo depicted a scene congruent with the action seen at encoding (implicit task from two still frames, Experiment 2), and when at encoding, they were presented a single still frame and evaluated at test whether a photo depicted a scene congruent with the action seen at encoding (implicit task from single still frame; Experiment 3). Overall, the results speak in favour of a mandatory mechanism through which our brain simulates the action also in tasks that do not explicitly require action simulation.

Motor imagery and engagement favour spatial reasoning.

Based on the assumption that spatial reasoning relies on the construction of mental models of the states of affairs described in the premises, and on evidence that sensory-motor imagery can enhance cognitive abilities, we hypothesised that imagining moving the objects mentioned in the premises to the specific spatial locations should favour spatial reasoning. The results of Experiment 1 confirmed the prediction: when participants imagined moving the objects mentioned in the premises (dynamic-engagement condition), they drew accurate inferences faster compared with participants who merely read the premises (static-non-engagement condition). Experiment 2 was in part a replication of Experiment 1 but included two additional experimental conditions to control for possible effects of self-engagement in reasoning: in one condition, participants imagined that someone else was moving the objects (dynamic-non-engagement condition), and in the other condition, participants imagined that they were observing the objects (static-engagement condition). The results revealed an interaction between motor imagery and engagement in decreasing response times to spatial problems. We discuss the practical implications of the current results.

Observer's body posture affects processing of other humans' actions.

Action observation triggers by default a mental simulation of action unfolding in time. We assumed that this simulation is "embodied": the body is the medium through which observer's sensorimotor modalities simulate the observed action. The participants in two experiments observed videos, each depicting the central part of an action performed by an actress on an object (e.g., answering the phone) and soon after each video they observed a photo portraying a state of the action not observed in the video, either depicting the initial part or the final part of the whole action. Their task was to evaluate whether the photo portrayed something before (backward photo) or after the action in the video (forward photo). Results showed that evaluation of forward photos was faster than evaluation of backward photos (Experiment 1). Crucially, participants' body posture modulated this effect: keeping the hands crossed behind the back interfered with forward simulations (Experiment 2). These results speak about the role of the observer's body posture in processing other people's actions.

Embodied cognition: So flexible as to be "disembodied"?

This review aims to explore what I call the "Embodiment Cost Hypothesis" (ECH), according to which, when humans "embody" a part of the world other than their bodies, a measurable cost is detectable on their real bodies. The review analyzes experimental evidence in favor of the ECH by examining studies from different research fields, including studies of action observation (2), tool-use (3), rubber hand illusion (4), and full-body illusions (5). In light of this literature, this review argues that embodiment effects can profitably be seen as phenomena associated with both benefits (resulting from the embodiment of external objects/bodies) and costs (resulting from the disembodiment at various levels of the subject's own body). Implications are discussed in relation to the ongoing debate on the embodied cognition (EC) approach.

Correction to: Embodied memories: Reviewing the role of the body in memory processes.

This paper omitted a reference: Dutriaux, L., & Gyselinck, V. (2016). Learning is better with the hands free: The role of posture in the memory of manipulable objects. PLOS ONE, 11(7), e0159108. doi:10.1371/journal.pone.0159108.

Embodied memories: Reviewing the role of the body in memory processes.

This review aims at exploring the role of the body and its sensorimotor processes in memory. Recent theories have suggested that memories can profitably be seen as mental simulations consisting in the reactivation of sensorimotor patterns originally associated with events at encoding, rather than amodal mental representations. The sensorimotor model of memory (SMM) claims that the body is the medium where (and through which) sensorimotor modalities actually simulate the somatosensory components of remembered events, and predicts that memory processes can be manipulated through manipulation of the body. The review analyzes experimental evidence in favor of the SMM and the claim that the body is at stake in memory processes. The review then highlights how, at the current state of research, the majority of this evidence concerns the effect of body manipulations on memory processes rather than memory representations. It considers the need for a more circumstantial outline of the actual extent to which the body is capable of affecting memory, specifically on some important areas still unexplored, such as the sense of recollection. Resulting strengths and limitations of the SMM are discussed in relation to the more general debate on the embodied cognition.

Mnemonic effects of action simulation from pictures and phrases.

Several theoretical approaches suggest that language comprehension and action observation rely on similar mental simulations. Granted that these two simulations partially overlap, we assumed that simulations stemming from action observations are more direct than those stemming from action phrases. The implied prediction was that simulation from action observation should prevail on simulation from action phrases when their effects are contrasted. The results of three experiments confirmed that, when at encoding the phrases were paired with pictures of actions whose kinematics was incongruent with the implied kinematics of the actions described in the phrases, memory for action phrases was impaired (Experiment 1). However, the reverse was not true: when the pictures were paired with phrases representing actions whose kinematics were incongruent with the kinematics of the actions portrayed in the pictures, memory for pictures portraying actions was not impaired (Experiment 2). Also, in line with evidence that simulations from action phrases and those from action observation partially overlap, when their effects were not contrasted their products were misrecognized. In our experiments, when action phrases only presented at recognition described actions depicted in pictures seen at encoding, they were misrecognized as had already been read at encoding (Experiment 1); further, when pictures only presented at recognition portrayed actions described in phrases presented at encoding, they were misrecognized as seen at encoding (Experiment 2). A third experiment excluded the possibility that the pattern of findings was simply a consequence of better memory for pictures of actions as opposed to memory for action phrases (Experiment 3). The implications of our results in relation to the literature on simulation in language comprehension and action observation are discussed.

The beneficial effect of a speaker's gestures on the listener's memory for action phrases: The pivotal role of the listener's premotor cortex.

Memory for action phrases improves in the listeners when the speaker accompanies them with gestures compared to when the speaker stays still. Since behavioral studies revealed a pivotal role of the listeners' motor system, we aimed to disentangle the role of primary motor and premotor cortices. Participants had to recall phrases uttered by a speaker in two conditions: in the gesture condition, the speaker performed gestures congruent with the action; in the no-gesture condition, the speaker stayed still. In Experiment 1, half of the participants underwent inhibitory rTMS over the hand/arm region of the left premotor cortex (PMC) and the other half over the hand/arm region of the left primary motor cortex (M1). The enactment effect disappeared only following rTMS over PMC. In Experiment 2, we detected the usual enactment effect after rTMS over vertex, thereby excluding possible nonspecific rTMS effects. These findings suggest that the information encoded in the premotor cortex is a crucial part of the memory trace.

Relevance of the listener's motor system in recalling phrases enacted by the speaker.

Memory for series of action phrases improves in listeners when speakers accompany each phrase with congruent gestures compared to when speakers stay still. Studies reveal that the listeners' motor system, at encoding, plays a crucial role in this enactment effect. We present two experiments on gesture observation, which explored the role of the listeners' motor system at recall. The participants listened to the phrases uttered by a speaker in two conditions in each experiment. In the gesture condition, the speaker uttered the phrases with accompanying congruent gestures, and in the no-gesture condition, the speaker stayed still while uttering the phrases. The participants were then invited, in both conditions of the experiments, to perform a motor task while recalling the phrases proffered by the speaker. The results revealed that the advantage of observing gestures on memory disappears if the listeners move at recall arms and hands (same motor effectors moved by the speaker, Experiment 1a), but not when the listeners move legs and feet (different motor effectors from those moved by the speaker, Experiment 1b). The results suggest that the listeners' motor system is involved not only during the encoding of action phrases uttered by a speaker but also when recalling these phrases during retrieval.

Timing of Gestures: Gestures Anticipating or Simultaneous With Speech as Indexes of Text Comprehension in Children and Adults.

The deep comprehension of a text is tantamount to the construction of an articulated mental model of that text. The number of correct recollections is an index of a learner's mental model of a text. We assume that another index of comprehension is the timing of the gestures produced during text recall; gestures are simultaneous with speech when the learner has built an articulated mental model of the text, whereas they anticipate the speech when the learner has built a less articulated mental model. The results of four experiments confirm the predictions deriving from our assumptions for both children and adults. Provided that the recollections are correct, the timing of gestures can differ and can be considered a further measure of the quality of the mental model, beyond the number of correct recollections.

The Multilingual CID-5: A New Tool to Study the Perception of Communicative Interactions in Different Languages.

The investigation of the ability to perceive, recognize, and judge upon social intentions, such as communicative intentions, on the basis of body motion is a growing research area. Cross-cultural differences in ability to perceive and interpret biological motion, however, have been poorly investigated so far. Progress in this domain strongly depends on the availability of suitable stimulus material. In the present method paper, we describe the multilingual CID-5, an extension of the CID-5 database, allowing for the investigation of how non-conventional communicative gestures are classified and identified by speakers of different languages. The CID-5 database contains 14 communicative interactions and 7 non-communicative actions performed by couples of agents and presented as point-light displays. For each action, the database provides movie files with the point-light animation, text files with the 3-D spatial coordinates of the point-lights, and five different response alternatives. In the multilingual CID-5 the alternatives were translated into seven languages (Chinese, Dutch, English, French, German, Italian, and Polish). Preliminary data collected to assess the recognizability of the actions in the different languages suggest that, for most of the action stimuli, information presented in point-light displays is sufficient for the distinctive classification of the action as communicative vs. individual, as well as for identification of the specific communicative gesture performed by the actor in all the available languages.

Stopping movements: when others slow us down.

Previous research has shown that performing joint actions can lead to the representation of both one's own and others' actions. In the present study we explored the influence of co-representation on response stopping. Are joint actions more difficult to stop than solo actions? Using a variation of the stop-signal task, we found that participants needed more time to stop a planned joint action compared with a planned solo action (Experiment 1). This effect was not observed when participants performed the task in the presence of a passive observer (Experiment 2). A third transcranial magnetic stimulation experiment (Experiment 3) demonstrated that joint stopping recruited a more selective suppression mechanism than solo stopping. Taken together, these results suggest that participants used a global inhibition mechanism when acting alone; however, they recruited a more selective and slower suppression mechanism when acting with someone else.

Learning from text benefits from enactment.

Classical studies on enactment have highlighted the beneficial effects of gestures performed in the encoding phase on memory for words and sentences, for both adults and children. In the present investigation, we focused on the role of enactment for learning from scientific texts among primary-school children. We assumed that enactment would favor the construction of a mental model of the text, and we verified the derived predictions that gestures at the time of encoding would result in greater numbers of correct recollections and discourse-based inferences at recall, as compared to no gestures (Exp. 1), and in a bias to confound paraphrases of the original text with the verbatim text in a recognition test (Exp. 2). The predictions were confirmed; hence, we argue in favor of a theoretical framework that accounts for the beneficial effects of enactment on memory for texts.