Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Joint Actions with Other Humans <s> Nine experiments of timed odd-even judgments examined how parity and number magnitude are accessed from Arabic and verbal numerals. With Arabic numerals, Ss used the rightmost digit to access a store of semantic number knowledge. Verbal numerals went through an additional stage of transcoding to base 10. Magnitude information was automatically accessed from Arabic numerals. Large numbers preferentially elicited a rightward response, and small numbers a leftward response. The Spatial-Numerical Association of Response Codes (SNARC) effect depended only on relative number magnitude and was weaker or absent with letters or verbal numerals. Direction did not vary with handedness or hemispheric dominance but was linked to the direction of writing, as it faded or even reversed in right-to-left writing Iranian Ss <s> BIB001 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Joint Actions with Other Humans <s> Objectives: Since the characteristics of the Bereitschaftspotential (BP) ‐ voluntary movement paradigm of internally-driven movements ‐ have been established recently by our group using high resolution DC-EEG techniques, it was of great interest to apply similar techniques to the other slow brain potential ‐ contingent negative variation (CNV) of externally-cued movements ‐ with the same motor tasks using the same subjects. Methods: The CNV for simple bimanual sequential movements (task 1), complex bimanual sequential movements (task 2) and a nonmotor condition (task 3) was recorded on the scalp using a 64 channel DC-EEG in 16 healthy subjects, and the data were analyzed with high resolution spatiotemporal statistics and current source density (CSD). Results: (1) The CNV was distributed over frontal, frontocentral, central and centroparietal regions; a negative potential was found at the frontal pole and a positive potential was found over occipital regions. (2) CNV amplitudes were higher for task 2 than for task 1, and there was no late CNV for task 3. (3) A high resolution spatiotemporal analysis revealed that during the early CNV component, statistical differences existed between the motor tasks (tasks 1 and 2) and the non-motor task (task 3), which occurred at frontocentral, central, centroparietal, parietal and parieto-occipital regions. During the late CNV component, additional significant differences were found not only between the motor tasks and the non-motor task but also between motor task 1 and task 2 at frontocentral, central and centroparietal regions. (4) Comparison of the CNV between the frontomesial cortex (situated over the supplementary/cingulate areas, SCMA) and both lateral pre-central areas (situated over the primary motor areas, MIs) showed that there was no statistically significant difference between the two cortical motor areas except for the early CNV. (5) Comparison of the CNV between the 3 tasks over the cortical motor areas showed that there were significant differences between the motor tasks and the non-motor task regarding the auditory evoked potential (AEP) and the early CNV component, and between all 3 tasks in the late CNV, the visual evoked potential (VEP2) and the N-P component. (6) The ranges and the densities of the CSD maps were larger and higher for complex than for simple tasks. The current sinks of the AEP and the early CNV were located at Fz, the late CNV at FCz and surrounding regions. As to be expected, current sources of the VEPs were located at the occipital lobes. The CNV was a current sink (negative) except for the VEP’s main component which was a current source (positive). Conclusions: (1) The CNV topography over the scalp varied with the complexity of motor tasks and between motor and non-motor conditions. (2) The origin of the early CNV may rest in the frontal lobes, while the late CNV may stem from more extensive cortical areas including SCMA, MIs, etc. (3) The late CNV component is not identical with the BP. q 2000 Elsevier Science Ireland Ltd. All rights reserved. <s> BIB002 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Joint Actions with Other Humans <s> Previous research has shown that observing others' actions can affect individual performance of the same actions. In the present study, we developed a new paradigm to investigate whether and how complementary actions at the disposal of another agent are represented and influence one's own actions. A spatial compatibility task was distributed among two people so that each participant took care of one of two responses. The identical task was performed alone and alongside another participant. There was a spatial compatibility effect in the group setting only. It was similar to the effect obtained when one person took care of both responses. This result suggests that one's own actions and others' actions are represented in a functionally equivalent way. <s> BIB003 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Joint Actions with Other Humans <s> Abstract The execution of efficient motor actions is often preceded by preparation in the central nervous system. Although this kind of preparation cannot be observed directly, it, nevertheless, shortens reaction time. In this review we focus on two types of action preparation, namely event and temporal preparation. In particular, we show how modern event-related brain potential techniques can be employed to determine both the covert processes underlying such preparatory effects as well as their locus within the processing chain between stimulus input and action output. <s> BIB004 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Joint Actions with Other Humans <s> It is thought that number magnitude is represented in an abstract and amodal way on a left-to-right oriented mental number line. Major evidence for this idea has been provided by the SNARC effect (Dehaene, Bossini, & Giraux, 1993): responses to relatively larger numbers are faster for the right hand, those to smaller numbers for the left hand, even when number magnitude is irrelevant. The SNARC effect has been used to index automatic access to a central semantic and amodal magnitude representation. However, this assumption of modality independence has never been tested and it remains uncertain if the SNARC effect exists in other modalities in a similar way as in the visual modality. We have examined this question by systematically varying modality/notation (auditory number word, visual Arabic numeral, visual number word, visual dice pattern) in a within-participant design. The SNARC effect was found consistently for all modality/notation conditions, including auditory presentation. The size of the SNARC effect in the auditory condition did not differ from the SNARC effect in any visual condition. We conclude that the SNARC effect is indeed a general index of a central semantic and amodal number magnitude representation. <s> BIB005 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Joint Actions with Other Humans <s> Traditionally, communication has been defined as the intentional exchange of symbolic information between individuals. In contrast, the mirror system provides a basis for nonsymbolic and nonintentional information exchange between individuals. We believe that understanding the role of the mirror system in joint action has the potential to serve as a bridge between these two domains. The present study investigates one crucial component of joint action: the ability to represent others' potential actions in the same way as one's own in the absence of perceptual evidence. In two experiments a joint spatial numerical association of response codes (SNARC) effect is demonstrated, providing further evidence that individuals form functionally equivalent representations of their own and others' potential actions. It is shown that numerical (symbolic) stimuli that are mapped onto a spatially arranged internal representation (a mental number line) can activate a co-represented action in the same way as spatial stimuli. This generalizes previous results on co-representation. We discuss the role of the mirror system in co-representation as a basis for shared intentionality and communication. <s> BIB006 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Joint Actions with Other Humans <s> We investigated whether people take into account an interaction partner's attentional focus and whether they represent in advance their partner's part of the task when planning to engage in a synchronous joint action. The experiment involved two participants planning and performing joint actions (i.e., synchronously lifting and clinking glasses), unimanual individual actions (i.e., lifting and moving a glass as if clinking with another person), and bimanual individual actions. EEG was recorded from one of the participants. We employed a choice reaction paradigm where a visual cue indicated the type of action to be planned, followed 1.5 sec later by a visual go stimulus, prompting the participants to act. We studied attention allocation processes by examining two lateralized EEG components, namely the anterior directing attention negativity and the late directing attention positivity. Action planning processes were examined using the late contingent negative variation and the movement-related potential. The results show that early stages of joint action planning involve dividing attention between locations in space relevant for one's own part of the joint action and locations relevant for one's partner's part of the joint action. At later stages of joint action planning, participants represented in advance their partner's upcoming action in addition to their own action, although not at an effector-specific level. Our study provides electrophysiological evidence supporting the operation of attention sharing processes and predictive self/other action representation during the planning phase of a synchronous joint task. <s> BIB007 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Joint Actions with Other Humans <s> The sense of agency refers to the feeling that we are in control of our actions and, through them, of events in the outside world. Much research has focused on the importance of retrospectively matching predicted and actual action outcomes for a strong sense of agency. Yet, recent studies have revealed that a metacognitive signal about the fluency of action selection can prospectively inform our sense of agency. Fluent, or easy, action selection leads to a stronger sense of agency over action outcomes than dysfluent, or difficult, selection. Since these studies used subliminal priming to manipulate action selection, it remained unclear whether supraliminal stimuli affecting action selection would have similar effects. We used supraliminal flankers to manipulate action selection in response to a central target. Experiment 1 revealed that conflict in action selection, induced by incongruent flankers and targets, led to reduced agency ratings over an outcome that followed the participant's response, relative to neutral and congruent flanking conditions. Experiment 2 replicated this result, and extended it to free choice between alternative actions. Finally, Experiment 3 varied the stimulus onset asynchrony (SOA) between flankers and target. Action selection performance varied with SOA. Agency ratings were always lower in incongruent than congruent trials, and this effect did not vary across SOAs. Sense of agency is influenced by a signal that tracks conflict in action selection, regardless of the visibility of stimuli inducing conflict, and even when the timing of the stimuli means that the conflict may not affect performance. <s> BIB008 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Joint Actions with Other Humans <s> Many studies suggest that individuals are not able to build a sense of we-agency during joint actions with automated artificial systems. We sought to examine whether or not this lack of sense of control was linked with individuals' inability to represent automaton-generated action into their own cognitive system. Indeed, during human interactions, we automatically represent our partner's actions in our own sensorimotor system. This might sustain our capacity to build a sense of we-agency over our partner-generated actions. However, to our knowledge, no studies have investigated the potential relation between our ability to use our sensorimotor system to represent a partner's action and we-agency. Our approach consisted in performing a pilot study coupling together a Simon target detection task wherein RTs served as an index of action co-representation and an implicit measure of one's sense of agency as indicated by intentional binding phenomenon. The preliminary observations suggested that individuals could represent other-generated action and have a sense of agency over these actions provided that their partner was another human and not an artificial automated system. <s> BIB009
Using a joint Simon task, Sebanz et al. (2003) have found evidence of a social Simon effect, suggesting that during joint actions, actions of others are represented in our own motor plan BIB003 . The standard Simon effect refers to the interference effect occuring when an individual has to respond with the right or left hand to a stimulus presented in an incongruent mapping location compared to a congruent mapping location  . A conflict occurs because two actions representations (i.e., the correct action to perform and the spatially-induced automatic activated action) are activated and the participant has to solve the conflict in order to select the accurate behavior. In BIB003 's first experiment, participants were shown pictures of a hand presented in the middle of the picture and pointing either to the left, to the middle or to the right side of the screen. On the index finger, there was a ring that could be either red or green. In the two-choice condition, the participant had to click on one of two boutons (left or right) according to the color of the ring. In the joint go-nogo condition, participants performed the task with a partner. Each of them had to respond to only one color by clicking on only one button. In the individual go-nogo condition, the participant was alone, and had to click only on one button associated with a given color. The experimental setting of the go-nogo conditions is presented in Figure 3 . For all the conditions, the pointing direction of the finger was irrelevant for the task but could still automatically pre-activate the hand of the participant if the finger was pointing at this hand and thus facilitate the response (or create a conflict). Critically, in the joint go-nogo condition, each paired participants had to be responsive to only one attributed color so that they only had to perform one action type as for the individual go-nogo condition (left or right key press) and unlike the two-choice condition where each participant had to manage two colors so that they could perform two alternative actions (left and right key presses). The sole difference between the two go-nogo conditions was that in the joint go-nogo condition, another person was performing a complementary action beside the participant whereas in the individual go-nogo condition the participant was performing his or her task alone. The underlying idea was that if performance in the joint go-nogo condition were similar to performance in the two-choice condition, then it must involve similar inner representation of action (i.e., the two actions (left and right key presses) were both represented in the two conditions). Participants' reaction times were shorter FIGURE 2 | Timeline of an incongruent trial in the study of BIB008 . After the fixation cross apparition, the participants were primed with incongruent target (H) and flankers (S). Then, they had to press the key associated with the central target (e.g., the right key for the H target). The key press triggered an outcome color after a variable delay of 100, 300, or 500 ms. Finally, the participants had to rate with a scale their perceived control over the outcome apparition. FIGURE 3 | Experimental setting of the Social Simon task in the study of BIB003 . In the joint go-nogo condition (a), two participants were sitting side by side and the target detection task was shared among then two individuals. In the individual go-nogo condition (b), the participants were sitting alone and they had to perform the target detection on their own. when the index finger was pointing toward the correct button to push than when the index finger was pointing toward the opposite button to push, both during the joint go-nogo and the two-choice conditions. This finding supports the idea that during joint actions, partner's actions are functionally represented in our own motor system and activated in an automatic way, as they can interfere with our own performance, even when it is not task-relevant. This result has been replicated by BIB009 using a variant of the paradigm. In the two-choice condition, participants had to press a right key when a green circle appeared either on the left or right side of the screen, and a left key when a red circle appeared on the left or right side of the screen. In the individual go-nogo condition, the participants had to only detect the green circle that appeared either on the left or right side of the screen by pressing the right key. In the joint go-nogo human-human condition, participants sat the right side of the screen and a confederate the left side. Participants had to detect the green circles with the right key, and the confederate was to detect the red circles with the left key. The authors analyzed the reaction times of the participants. Consistently, the authors found a compatibility effect (faster reaction times when the target appeared on the same side as the participant response key compared to when the target appeared on the opposite side) only in the two-choice and joint go-nogo human-human conditions, thus supporting a social Simon effect. The ability to represent the actions of a partner has also been shown with a more abstract concept, such as the SNARC effect BIB006 . This effect relies on the fact that we represent numbers in our mind across a line where the small numbers are represented toward the beginning of the line (on the left) and the large numbers toward the other end of the line BIB001 BIB005 . It has been shown that participants were faster to respond to small numbers when they had to press a left key to answer and faster to respond to large numbers when they had to press a right key to answer BIB001 . This occurs because the activation of the left/right part of the mental line triggers a pre-activation of left-/right-handed actions, leading to a facilitation effect. BIB006 tested the hypothesis of a joint SNARC effect. In their study, participants had to respond to number parity for numbers between 2 and 9 with a left or right key. In the joint go-nogo condition, participants worked in pair. One had to react to the even numbers with one button whereas the other had to react to the odd numbers with the opposite button. In the individual gonogo condition, participants worked alone. They had to perform exactly the same task than in the joint go-nogo condition except that there was no partner to perform a complementary action. In the two-choice condition, participants worked alone and had to respond both to the even and odd numbers with the appropriate button. The experimental setting of the Social SNARC Simon experiment is presented in Figure 4 . Consistent with BIB003 , data showed a SNARC effect occuring during the two-choice condition and the joint go-nogo condition but not FIGURE 4 | Experimental setting of the Social SNARC Simon task in the study of BIB006 . In the two-choice condition (A), the participants had to detect both the even numbers with a button and the odd numbers with the opposite button. In the go-nogo conditions (B), the participants had to detect only one sort of number (e.g. only the odd numbers) with one specific button. during the individual go-nogo condition. The presence of a joint SNARC effect suggests that each co-agent represented both his or her own action and the other's action so that conflict between two possible action alternatives occurred, as in the two-choice condition. These behavioral data are supported by neurophysiological investigations. The contingent negative variation (CNV) is a slow negative brain wave arising during the last stages of action planning and can be considered as an index of other's actions representation as the CNV is effector-independent BIB004 . Complex motor tasks lead to higher CNV amplitude BIB002 . Authors have shown that the amplitude of the CNV was stronger when participants prepared a joint unimanual action compared to the same unimanual action realized in a personal way BIB007 . This pattern of results has been proposed to reflect that participants have implicitly represented the action of their partner in their own system during the joint action so that the content represented was more complex (explaining the CNV enhancement) whereas it was not the case during the individual action BIB007 . In sum, when we perform joint actions with other people, we automatically represent the partner's task in our own motor planning. Hence, through the same predictive mechanisms underliying action execution, it is possible to anticipate the motor goal of the partner's action with the aim to promote successful interactions.