The joint flanker effect: Less social than previously thought

Research on joint action has been taken to suggest that actors automatically co-represent the tasks and/or actions of co-actors. However, recent findings on the joint Simon effect have provided evidence for a nonsocial account, which renders automatic co-representation unlikely. In the present study, we aimed to test whether a nonsocial account is also feasible for the joint version of the flanker task. In particular, we manipulated the social nature of the “co-actor” who could be another human or a Japanese waving cat. Contrary to the social interpretation of the joint flanker effect, the results demonstrated a “joint” flanker effect, irrespective of whether participants shared the task with another person or with the Japanese waving cat.     

冲突适应效应是领域特定的

本研究采用整合的交叉任务范式,通过任务类型的操纵,对冲突适应效应是领域一般的还是领域特定的问题进行了探讨。结果发现当时,在刺激-反应集为4的字母flanker+Simon的整合交叉任务中和刺激-反应集为4的Stroop+Simon的整合交叉任务中,冲突适应效应都是仅存在于任务内,不存在于任务间。说明在控制了重复启动效应且排除了任务之间维度重叠的影响后,两种类型的整合交叉任务都只在任务内观察到冲突适应效应。这表明在控制特征整合的影响后,冲突适应效应是领域特定的,同时说明冲突监测系统不仅是对冲突进行监测,也对冲突的来源进行识别。     

Flanker and Simon effects interact at the response selection stage

The present study aimed at investigating the processing stage underlying stimulus–stimulus (S–S) congruency effects by examining the relation of a particular type of congruency effect (i.e., the flanker effect) with a stimulus–response (S–R) spatial correspondence effect (i.e., the Simon effect). Experiment 1 used a unilateral flanker task in which the flanker also acted as a Simon-like accessory stimulus. Results showed a significant S–S Congruency × S–R Correspondence interaction: An advantage for flanker–response spatially corresponding trials was observed in target–flanker congruent conditions, whereas, in incongruent conditions, there was a noncorresponding trials' advantage. The analysis of the temporal trend of the correspondence effects ruled out a temporal-overlap account for the observed interaction. Moreover, results of Experiment 2, in which the flanker did not belong to the target set, demonstrated that this interaction cannot be attributed to perceptual grouping of the target–flanker pairs and referential coding of the target with respect to the flanker in the congruent and incongruent conditions, respectively. Taken together, these findings are consistent with a response selection account of congruency effects: Both the position and the task-related attribute of the flanker would activate the associated responses. In noncorresponding-congruent trials and corresponding-incongruent trials, this would cause a conflict at the response selection stage.     

Influence of time-of-day on joint Navon effect

The shared attention theory suggests that people devote greater cognitive resources to those features co-attended simultaneously with others, determining better performance in several types of tasks. When co-actors performed a go/no-go Navon task attending different features of target letters, the performance was impaired, reflecting a joint Navon effect (the representation of a co-actor’s attentional focus made it more difficult to select and apply one’s own focus of attention), probably due to asynchronous co-attention with a decrease in cognitive resources involved. Researches in chronobiology and chronopsychology demonstrated that not only selective attention (involved in a Navon task), but also cognitive resources have a daily fluctuations, mainly paralleling the circadian rhythm of body temperature (i.e. increasing values from the morning to evening with a subsequent decline in the night). The study was conducted to assess whether the presence of joint attention, as measured by the joint Navon effect, was influenced by the time-of-day. Sixteen pairs of participants sitting next to each other were required to respond to the identity letters in a go/no-go Navon task twice: in the morning (09:00–10:00) and early afternoon (13:00–14:00). The results showed a joint Navon effect in the morning session only, suggesting that joint attention was affected by the time-of-day effect on cognitive resources.     

Do you see what I see? Co-actor posture modulates visual processing in joint tasks

ABSTRACT

Interacting with other people is a ubiquitous part of daily life. A complex set of processes enable our successful interactions with others. The present research was conducted to investigate how the processing of visual stimuli may be affected by the presence and the hand posture of a co-actor. Experiments conducted with participants acting alone have revealed that the distance from the stimulus to the hand of a participant can alter visual processing. In the main experiment of the present paper, we asked whether this posture-related source of visual bias persists when participants share the task with another person. The effect of personal and co-actor hand-proximity on visual processing was assessed through object-specific benefits to visual recognition in a task performed by two co-actors. Pairs of participants completed a joint visual recognition task and, across different blocks of trials, the position of their own hands and of their partner's hands varied relative to the stimuli. In contrast to control studies conducted with participants acting alone, an object-specific recognition benefit was found across all hand location conditions. These data suggest that visual processing is, in some cases, sensitive to the posture of a co-actor.     

Opposing influences on conflict-driven adaptation in the Eriksen flanker task

Compatibility effects in conflict paradigms are reduced following incompatible trials, and this effect is referred to as conflict adaptation. A perplexing pattern exists, however, with conflict-driven adaptation emerging in several paradigms (e.g., Stroop, Simon) but not consistently in the Eriksen and Eriksen (1974) flanker task. The present experiments address the seemingly elusive presence of conflict adaptation in this task. Experiment 1 shows that a negative-priming-like slowing may be masking conflict adaptation in the flanker task. In Experiment 2, conflict adaptation was revealed when a larger stimulus set designed to reduce negative priming was implemented. Taken together, the findings indicate that a consideration of processes opposing conflict adaptation in the flanker task may help reconcile prior findings.     

Stimulus–response compatibility for mixed mappings and tasks with unique responses

For two stimulus locations mapped to two keypresses, reaction time is shorter when the mapping is compatible than when it is not (the stimulus–response compatibility, SRC, effect). A similar result, called the Simon effect, occurs when stimulus location is irrelevant, and colour is relevant. When compatibly mapped trials are intermixed with incompatibly mapped trials or Simon task trials, the compatibility effect is eliminated, and the Simon effect is influenced by the location mapping. In five experiments, we examined whether similar mixing effects occur when the two spatial mappings or location-relevant and location-irrelevant tasks use distinct keypresses on the left and right hands. Mixing had considerably less influence on the SRC and Simon effects than it does when the intermixed trial types or tasks share the same responses, even though response time was lengthened to a similar extent. Mixing two tasks for which stimulus location was irrelevant yielded no within-task Simon effect, but the effect was also absent when four stimuli were assigned to two responses on a single hand. The relative lack of influence of mixing on the SRC and Simon effects when the tasks have unique responses implies that suppression of direct activation of the corresponding response occurs primarily when the tasks share responses.     

A response-discrimination account of the Simon effect

Simon effects might partly reflect stimulus-triggered response activation. According to the response-discrimination hypothesis, however, stimulus-triggered response activation shows up in Simon effects only when stimulus locations match the top-down selected spatial codes used to discriminate between alternative responses. Five experiments support this hypothesis. In Experiment 1, spatial codes of each response differed by horizontal and vertical axis position, yet one axis discriminated between alternative responses, whereas the other did not. Simon effects resulted for targets on discriminating axes only. In Experiment 2, both spatial axes discriminated between responses, and targets on both axes produced Simon effects. In Experiment 3, Simon effects resulted for a spatial choice-reaction task but not for a go/no-go task. Even in the go/no-go task, a Simon effect was restored when a two-choice reaction task preceded the go/no-go task (Experiment 4) or when participants initiated trials with responses spatially discriminated from the go response (Experiment 5).     

Modes of spatial coding in the Simon task*

Many models of the Simon effect assume that categorical spatial representations underlie the phenomenon. The present study tested this assumption explicitly in two experiments, both of which involved eight possible spatial positions of imperative stimuli arranged horizontally on the screen. In Experiment 1, the eight stimulus locations were marked with eight square boxes that appeared at the same time during a trial. Results showed gradually increasing Simon effects from the central locations to the outer locations. In Experiment 2, the eight stimulus locations consisted of a combination of three frames of spatial reference (hemispace, hemifield, and position relative to the fixation), with each frame appearing in different timings. In contrast to Experiment 1, results showed an oscillating pattern of the Simon effect across the horizontal positions. These findings are discussed in terms of grouping factors involved in the Simon task. The locations seem to be coded as a single continuous dimension when all are visible at once as in Experiment 1, but they are represented as a combination of the lateral categories (“left” vs. “right”) with multiple frames of reference when the reference frames are presented successively as in Experiment 2.     

Inverting the joint Simon effect by intention

The joint Simon effect (JSE) is a spatial-compatibility effect that emerges when two people complete complementary components of a Simon task. In typical JSE studies, two participants sit beside each other and perform go-no-go tasks in which they respond to one of two stimuli by pressing a button. According to the action co-representation account, JSEs emerge because each participant represents their partner's response in addition to their own, causing the same conflicts in processing that would occur if an individual responded to both stimuli (i.e., as in a two-choice task). Because the response buttons are typically in front of participants, however, an alternative explanation is that JSEs are the result of a dimensional overlap between target and response locations coded with respect to another salient object (e.g., the co-actor's effector). To contrast these hypotheses, the participants in the present study completed two-choice and joint Simon tasks in which they were asked to focus on generating an aftereffect in the space contralateral to their response. Hommel (Psychological Research 55:270-279, 1993) previously reported that, when participants completed a two-choice task under such effect-focused instructions, spatial-compatibility effects emerged that were based on the aftereffect location instead of the response location. Consistent with the co-representation account, the results of the present study were that an inverse aftereffect-based (i.e., not a response-location-based) compatibility effect was observed in both the two-choice and joint tasks. The overall pattern of results does not fit with the spatial-coding account and is discussed in the context of the extant JSE literature.     

Shared learning shapes human performance: Transfer effects in task sharing

We investigated whether performing a task with a co-actor shapes the way a subsequent task is performed. In four experiments participants were administered a Simon task after practicing a spatial compatibility task with an incompatible S-R mapping. In Experiment 1 they performed both tasks alongside another person; in Experiment 2 they performed the spatial compatibility task alone, responding to only one stimulus position, and the Simon task with another person; in Experiment 3, they performed the spatial compatibility task with another person and the Simon task alone; finally, in Experiment 4, they performed the spatial compatibility task alone and the Simon task with another person. The incompatible practice eliminated the Simon effect in Experiments 1 and 4. These results indicate that when a task is distributed between two participants with each one performing a different part of it, they tend to represent the whole task rather than their own part of it. This experience can influence the way a subsequent task is performed, as long as this latter occurs in a social context.     

Endogenous orienting modulates the Simon effect: critical factors in experimental design

Responses are faster when the side of stimulus and response correspond than when they do not correspond, even if stimulus location is irrelevant to the task at hand: the correspondence, spatial compatibility effect, or Simon effect. Generally, it is assumed that an automatically generated spatial code is responsible for this effect, but the precise mechanism underlying the formation of this code is still under dispute. Two major alternatives have been proposed: the referential-coding account, which can be subdivided into a static version and an attention-centered version, and the attention-shift account. These accounts hold clear-cut predictions for attentional cuing experiments. The former would assume a Simon effect irrespective of attentional cuing in its static version, whereas the attention-centered version of the referential-coding account and the attention-shift account would predict a decreased Simon effect on validly as opposed to invalid cued trials. However, results from previous studies are equivocal to the effects of attentional cuing on the Simon effect. We argue here that attentional cueing reliably modulates the Simon effect if some crucial experimental conditions, mostly relevant for optimizing attentional allocation, are met. Furthermore, we propose that the Simon effect may be better understood within the perspective of supra-modal spatial attention, thereby providing an explanation for observed discrepancies in the literature.     

三维空间中视觉空间返回抑制对Simon效应的影响

通过虚拟现实技术构建虚拟三维场景,采用视觉空间返回抑制范式与Simon任务的变式相结合,操纵了目标深度、线索有效性以及空间一致性三个变量,考察三维空间深度位置上视觉空间返回抑制如何影响任务无关的反应表征(Simon效应)。结果发现,(1)三维空间深度位置上存在基于空间的返回抑制效应,且空间返回抑制效应会削减Simon效应;(2)目标出现在远处空间时,线索化条件下的Simon效应显著大于非线索化条件下的Simon效应;(3)目标出现在近处空间时,线索化条件与非线索化条件下的Simon效应之间无显著差异。研究表明,空间返回抑制并不是"深度盲",且目标的空间位置会对空间返回抑制与Simon效应的交互关系产生影响。     

Distance and ratio effects in the flanker task are due to different mechanisms

When participants must respond to a relevant central target and ignore irrelevant flanking stimuli the flanking stimuli produce a compatibility effect, with increased response speed and accuracy on compatible as compared to incompatible trials. This flanker effect is larger when compatible trials are more frequent than incompatible trials (the ratio effect). A potential explanation of this ratio effect is that the occurrence of frequent incompatible trials causes the focus of spatial attention to be set narrower than when there are frequent compatible trials. The present investigation tests this hypothesis by comparing the flanker effect with near and far flankers. The hypothesis predicts that the flanker distance should modulate the ratio effect more when incompatible trials are frequent than when compatible trials are frequent. The results, however, show the opposite pattern: Distance effects are larger in conditions with frequent compatible trials. Moreover, the effect of distance but not the ratio effect was eliminated when flanker distance remained fixed across blocks of trials, and also when participants had to attend to flanker stimuli in a go-no-go task. These results suggest that the ratio effect does not result from an adjustment of the focus of spatial attention.     

Modulation of the affordance effect through transfer of learning

Consistent evidence shows that practising with spatially incompatible stimulus–response trials modulates performance on following tasks requiring the solution of cognitive conflict such as the Simon and Stroop tasks. In the present study we assessed whether a spatially incompatible practice can modulate another effect that is thought to be due to a conflict between two response alternatives, the affordance effect. To this end, we requested participants to categorize pictures of common objects on the basis of their upright or inverted orientation. A group of participants performed the categorization task alone, while the other two groups performed the categorization task after practising with a spatial compatibility task with either a compatible or an incompatible mapping. Results showed that the spatially incompatible practice eliminated the affordance effect. These results indicate that the conflict at the basis of the affordance effect is not unavoidable but it rather permeable to modulations affecting the response selection stage. Indeed the “emit the alternative spatial response” rule acquired during the spatially incompatible task can transfer to and modulate how the subsequent affordance task is performed.     

Action co-representation and the sense of agency during a joint Simon task: Comparing human and machine co-agents

Recent studies have suggested that individuals are not able to develop a sense of joint agency during joint actions with artificial systems. We sought to examine whether this lack of joint agency is linked to individuals’ inability to co-represent the machine-generated actions. Fifteen participants observed or performed a Simon response time task either individually, or jointly with another human or a computer. Participants reported the time interval between their response (or the co-actor response) and a subsequent auditory stimulus, which served as an implicit measure of participants’ sense of agency. Participants’ reaction times showed a classical Simon effect when they were partnered with another human, but not when they collaborated with a computer. Furthermore, participants showed a vicarious sense of agency when co-acting with another human agent but not with a computer. This absence of vicarious sense of agency during human-computer interactions and the relation with action co-representation are discussed.     

Response-compatibility effects in children

The Eriksen Flanker task is a classic paradigm for investigating interference at the level of response compatibility. Several previous studies analyzed the ability of young children (starting at the age of four years) to ignore flanking distractors in children-specific variants of the task. However, in all published studies the interference took place at the perceptual level as well as on the level of response compatibility because the ‘compatible condition’ involved stimulus congruency as well as response compatibility. By confounding stimulus congruency and response compatibility, interference at the level of response programming and priming at the perceptual level cannot be distinguished: the observed flanker effects might not be the result of successfully ignoring but instead might just be explained due to priming. We tested 57 children aged between 7 and 12 years in a flanker variant in which all trials were perceptually incongruent but different at the level of response compatibility (compatible versus incompatible). Children showed a flanker effect (faster reaction times in response compatible trials) that was, however, in terms of the effect size, smaller than flanker effects reported in previous studies.     

情绪对联合行动中共同表征能力的影响机制

采用联合Simon任务通过3个实验探究不同情绪维度对联合任务中共同表征能力的影响机制。实验1a、1b分别考察在高、低唤醒度条件下不同效价对个体共同表征能力的影响; 实验2在此基础上进一步探索动机维度在其中的作用。结果发现：无论效价高低, 高唤醒度都是提高个体共同表征能力的关键因素, 且动机强度在其中起一定调节作用; 而在低唤醒度条件下, 高效价会起一定补偿作用。上述结果很好地支持了参照编码假说, 也澄清了情绪不同维度对联合动作表征的影响机制。     

Distance and ratio effects in the flanker task are due to different mechanisms

When participants must respond to a relevant central target and ignore irrelevant flanking stimuli the flanking stimuli produce a compatibility effect, with increased response speed and accuracy on compatible as compared to incompatible trials. This flanker effect is larger when compatible trials are more frequent than incompatible trials (the ratio effect). A potential explanation of this ratio effect is that the occurrence of frequent incompatible trials causes the focus of spatial attention to be set narrower than when there are frequent compatible trials. The present investigation tests this hypothesis by comparing the flanker effect with near and far flankers. The hypothesis predicts that the flanker distance should modulate the ratio effect more when incompatible trials are frequent than when compatible trials are frequent. The results, however, show the opposite pattern: Distance effects are larger in conditions with frequent compatible trials. Moreover, the effect of distance but not the ratio effect was eliminated when flanker distance remained fixed across blocks of trials, and also when participants had to attend to flanker stimuli in a go–no-go task. These results suggest that the ratio effect does not result from an adjustment of the focus of spatial attention.     

Transfer of noncorresponding spatial associations to the auditory Simon task

Four experiments examined transfer of noncorresponding spatial stimulus-response associations to an auditory Simon task for which stimulus location was irrelevant. Experiment 1 established that, for a horizontal auditory Simon task, transfer of spatial associations occurs after 300 trials of practice with an incompatible mapping of auditory stimuli to keypress responses. Experiments 2-4 examined transfer effects within the auditory modality when the stimuli and responses were varied along vertical and horizontal dimensions. Transfer occurred when the stimuli and responses were arrayed along the same dimension in practice and transfer but not when they were arrayed along orthogonal dimensions. These findings indicate that prior task-defined associations have less influence on the auditory Simon effect than on the visual Simon effect, possibly because of the stronger tendency for an auditory stimulus to activate its corresponding response.