The influence of action observation on action execution: Dissociating the contribution of action on perception,perception on action,and resolving conflict

For more than 15 years, motor interference paradigms have been used to investigate the influence of action observation on action execution. Most research on so-called automatic imitation has focused on variables that play a modulating role or investigated potential confounding factors. Interestingly, furthermore, a number of functional magnetic resonance imaging (fMRI) studies have tried to shed light on the functional mechanisms and neural correlates involved in imitation inhibition. However, these fMRI studies, presumably due to poor temporal resolution, have primarily focused on high-level processes and have neglected the potential role of low-level motor and perceptual processes. In the current EEG study, we therefore aimed to disentangle the influence of low-level perceptual and motoric mechanisms from high-level cognitive mechanisms. We focused on potential congruency differences in the visual N190 ? a component related to the processing of biological motion, the Readiness Potential ? a component related to motor preparation, and the high-level P3 component. Interestingly, we detected congruency effects in each of these components, suggesting that the interference effect in an automatic imitation paradigm is not only related to high-level processes such as self-other distinction but also to more low-level influences of perception on action and action on perception. Moreover, we documented relationships of the neural effects with (autistic) behavior.     

Stratification in perception and action

Summary This paper discusses the concept of stratification, in the sense of levels of analysis and levels of control, in relation to human perception and performance. It is contended that functional analysis is the proper level of analysis for the domain of perception and action. This is illustrated by means of models of cognitive energetics and motor control. The functional level of analysis can be situated in between the level of symbolic representations and the level of neurophysiological mechanisms. It is also argued that the concept of levels of control provides a way of integrating or relating ecological and information-processing approaches to psychology, in the sense that ecological psychology is concerned with lower and more peripheral levels of control (coordinative structures). Finally, some remarks are made on the relation between cognition and perception and action, drawing on Piaget, and it is proposed that the concept of schema is more appropriate for the domain of perception and action than is the notion of symbolic representations.     

Representing serial action and perception

This article presents a review on the representational base of sequence learning in the serial reaction time task. The first part of the article addresses the major questions and challenges that underlie the debate on implicit and explicit learning. In the second part, the informational content that underlies sequence representations is reviewed. The latter issue has produced a rich and equivocal literature. A taxonomy illustrates that substantial support exists for associations between successive stimulus features, between successive response features, and between successive response-to-stimulus compounds. We suggest that sequence learning is not predetermined with respect to one particular type of information but, rather, develops according to an overall principle of activation contingent on task characteristics. Moreover, substantiating such an integrative approach is proposed by a synthesis with the dual-system model (Keele, Ivry, Mayr, Hazeltine, & Heuer, 2003).     

The interaction of attention and action: From seeing action to acting on perception

We discuss evidence indicating that human visual attention is strongly modulated by the potential of objects for action. The possibility of action between multiple objects enables the objects to be attended as a single group, and the fit between individual objects in a group and the action that can be performed influences responses to group members. In addition, having a goal state to perform a particular action affects the stimuli that are selected along with the features and area of space that is attended. These effects of action may reflect statistical learning between environmental cues that are linked by action and/or the coupling between perception and action systems in the brain. The data support the argument that visual selection is a flexible process that emerges as a need to prioritize objects for action.     

Somatosensory processes subserving perception and action

The functions of the somatosensory system are multiple. We use tactile input to localize and experience the various qualities of touch, and proprioceptive information to determine the position of different parts of the body with respect to each other, which provides fundamental information for action. Further, tactile exploration of the characteristics of external objects can result in conscious perceptual experience and stimulus or object recognition. Neuroanatomical studies suggest parallel processing as well as serial processing within the cerebral somatosensory system that reflect these separate functions, with one processing stream terminating in the posterior parietal cortex (PPC), and the other terminating in the insula. We suggest that, analogously to the organisation of the visual system, somatosensory processing for the guidance of action can be dissociated from the processing that leads to perception and memory. In addition, we find a second division between tactile information processing about external targets in service of object recognition and tactile information processing related to the body itself. We suggest the posterior parietal cortex subserves both perception and action, whereas the insula principally subserves perceptual recognition and learning.     

Inhibition of return in perception and action

Inhibition of return (IOR) refers to the delay in responses to previously cued locations. Whether IOR influences perceptual and/or motor processes has been controversial. To determine IOR effects on perception and action, this study examined IOR in spatially directed hand reaching (Experiment 1) and spatial localization of targets with a mouse cursor (i.e., an indirect visuomotor mapping/perceptual task; Experiment 2). The reaction times showed delayed responses for targets appearing within the whole cued hemifield for both tasks. However, hypometric spatial biases were consistently found only with directed reaching. Spatial biases in the mouse localization task were indirectly influenced by IOR and distinct from those in the reaching task. The dissociation in spatial characteristics for directed reaching vs. perception suggests that the effects of IOR are task dependent, but may be more directly linked to the dorsal motor system.     

The distorted hand metric representation serves both perception and action

ABSTRACT

The representation of our body location is achieved by integrating sensorimotor inputs with information about our body size. Previous studies have shown that the metric representation of our hand, also called the body model, is distorted, namely overestimated in width and underestimated in length, although we are able to perform accurate fine movements. Considering the known dissociation between action-oriented and perception-oriented body representations, we asked whether the body model mainly serves body perception or whether it is also involved in movements. Twenty-one healthy adults were administered with the Localization Task (LT) which required the participants to localise the perceived position of their unseen hand by means of a stick held by their other hand, and the Proprioceptive Matching Task (PMT) which required the participants to match their perceived hand position with a visual target. LT and PMT maps were compared with the actual hand sizes. We found that the PMT map exhibited similar body model distortions, confirming that the body model is involved in motor programming. Furthermore, we observed that a partial adjustment of the distortions occurs in a motor condition.     

The effect of pre-cueing on spatial attention across perception and action

It is well established that processes of perception and action interact. A key question concerns the role of attention in the interaction between perception-action processes. We tested the hypothesis that spatial attention is shared by perception and action. We created a dual-task paradigm: In one task, spatial information is relevant for perception (spatial-input task) but not for action, and in a second task, spatial information is relevant for action (spatial-output task) but not for perception. We used endogenous pre-cueing, with two between-subjects conditions: In one condition the cue was predictive only for the target location in the spatial-input task; in a second condition the cue was predictive only for the location of the response in the spatial-output task. In both conditions, the cueing equally affected both tasks, regardless of the information conveyed by the cue. This finding directly supports the shared input-output attention hypothesis.     

The action dynamics of overcoming the truth

A convincing deceiver must act in discordance with their knowledge of the truth. To do so requires the deceiver to resolve competition between what is known to be true and what is intended to be false. We investigated the temporal signature of this competition by examining the action dynamics of arm movement while participants responded falsely or truthfully to autobiographical information. The participants answered no or yes by navigating a Nintendo Wii Remote to no and yes regions on a large projector screen. Trajectory analyses of the fine-grained arm movements show increased complexity in false responding relative to truthful responding, with the greatest difference in false yes answers. The dynamic motor movements also reveal greater strength of competition during the act of false responding, thereby extending traditional response time measures that capture latent competition alone. These results suggest that deceptive processes may be detectable when action is allowed to covary with thought. Supplemental figures and a list of the sentence stimuli may be downloaded from http://pbr.psychonomic-journals.org/content/supplemental.     

The effects of local and global processing demands on perception and action

The line-bisection task, adapted to utilise a wooden rod as the bisection stimulus, has revealed that patients with visuo-spatial neglect may be more accurate at bisection when asked to pick up the rod, compared to pointing to its centre. We recently reported that neurologically intact participants show a similar dissociation on this task-demonstrating a rightward bias when pointing to the centre, which was not present when grasping the rod by the centre. The current paper examined how pointing and grasping responses were affected by adapted rod-bisection tasks that emphasised local or global processing. In Experiment 1, 26 participants completed four rod-bisection tasks. The rods were compound stimuli and the participants directed to focus on either the local or global level. The results demonstrated that when participants focused on the global level, the previous dissociations found for pointing and grasping conditions were evident. However, the perception of centre did change when participants focused on the local level: both the pointing and grasping responses were rightward biased. In Experiment 2, 42 participants completed three bisection tasks which again emphasised either the local or global level, but in different sets of stimuli. The results of this task further support the findings in Experiment 1: the rightward bias in the local-bisection task was again evident and in addition, the global-bisection task resulted in no bias and no difference between the pointing and grasping bisections. These results demonstrate how task demands can similarly affect the pointing and grasping responses, and indicate that local and global processing may be involved in perception/action dissociations on rod bisection.     

The contextual action relationship between a tool and its action recipient modulates their joint perception

Facilitatory effects have been noted between tools and the objects that they act upon (their “action recipients”) across several paradigms. However, it has not been convincingly established that the motor system is directly involved in the joint visual processing of these object pairings. Here, we used the attentional blink (AB) paradigm to demonstrate privileged access to perceptual awareness for tool–action recipient object pairs and to investigate how motor affordances modulate their joint processing. We demonstrated a reduction in the size of the AB that was greater for congruent tool–action recipient pairings (e.g., hammer–nail) than for incongruent pairings (e.g., scissors–nail). Moreover, the AB was reduced only when action recipients followed their associated tool in the temporal sequence, but not when this order was reversed. Importantly, we also found that the effect was sensitive to manipulations of the motor congruence between the tool and the action recipient. First, we observed a greater reduction in the AB when the tool and action recipient were correctly aligned for action than when the tool was rotated to face away from the action recipient. Second, presenting a different tool as a distractor between the tool and action recipient target objects removed any benefit seen for congruent pairings. This was likely due to interference from the motor properties of the distractor tool that disrupted the motor synergy between the congruent tool and action recipient targets. Overall, these findings demonstrate that the contextual motoric relationship between tools and their action recipients facilitates their visual encoding and access to perceptual awareness.     

Neural dynamics of 3-D surface perception: figure-ground separation and lightness perception

This article develops the FACADE theory of three-dimensional (3-D) vision to simulate data concerning how two-dimensional pictures give rise to 3-D percepts of occluded and occluding surfaces. The theory suggests how geometrical and contrastive properties of an image can either cooperate or compete when forming the boundary and surface representations that subserve conscious visual percepts. Spatially long-range cooperation and short-range competition work together to separate boundaries of occluding figures from their occluded neighbors, thereby providing sensitivity to T-junctions without the need to assume that T-junction "detectors" exist. Both boundary and surface representations of occluded objects may be amodally completed, whereas the surface representations of unoccluded objects become visible through modal processes. Computer simulations include Bregman-Kanizsa figure-ground separation, Kanizsa stratification, and various lightness percepts, including the Münker-White, Benary cross, and checkerboard percepts.     

Fitts's law holds for action perception

Fitts's law is one of the most well-established principles in psychology. It captures the relation between speed and accuracy in performed and imagined movements. The aim of this study was to determine whether this law also holds during the perception of other people's actions. Subjects were shown apparent motion displays of a person moving his arm between two identical targets. Target width, the separation between targets, and movement speed were varied. Subjects reported whether the person could move at the perceived speed without missing the targets. The movement times reported as being just possible were exactly those predicted by Fitts's law (r(2)= .96). A subsequent experiment demonstrated the same lawful relation for the perception of a robot arm (r(2)= .93). To our knowledge, this makes Fitts's law the first motor principle that holds in imagery and the perception of biological and non-biological agents.     

Off-line authorship effects in action perception

Does the perception of our actions differ from the perception of other individuals' actions when we observe them, like other individual's actions, in an offline perspective? Previous studies, using recognition as well as prediction judgments, suggest that it does even if the stimulus information is reduced to a single moving point-light. Here, we assessed whether this difference also affects the timing of actions. This was tested in two experiments, using a specific synchronization task. After some practice, self-generated action events were anticipated faster than other action events, provided that the anticipation could not be accomplished sufficiently well on the basis of easily detectable cues. The results are discussed with regard to the previous findings of off-line authorship effects in action perception.     

Dissociating perception and action in Kanizsa's compression illusion

When a horizontally elongated surface is occluded in the middle by a larger surface, it appears narrower than its true width (Kanizsa’s compression illusion). We report that a similar compression effect occurs for closed-loop visuomotor matches of size, but not for otherwise comparable open-loop “mimed” reaching or size-matching visuomotor responses. Our study is the first in which a comparison of size perception in personal space with bilateral actions performed with both hands (instead of precision grips employing the thumb and the index finger) is used to investigate motor responses to Kanizsa’s compression illusion. Implications for the current debate on the existence of dissociations between spatial perception and visually controlled actions in personal space are discussed.     

Visual space perception and visually directed action.

The results of two types of experiments are reported. In 1 type, Ss matched depth intervals on the ground plane that appeared equal to frontal intervals at the same distance. The depth intervals had to be made considerably larger than the frontal intervals to appear equal in length, with this physical inequality of equal-appearing intervals increasing with egocentric distance of the intervals (4 m-12 m). In the other type of experiment, Ss viewed targets lying on the ground plane and then, with eyes closed, attempted either to walk directly to their locations or to point continuously toward them while walking along paths that passed off to the side. Performance was quite accurate in both motoric tasks, indicating that the distortion in the mapping from physical to visual space evident in the visual matching task does not manifest itself in the visually open-loop motoric tasks.     

Visual space perception and action: Introductory remarks

Vision evolved from the vital necessity to act in a dynamic environment. Following this view it is clear that perceptual processes and action planning are much more interlocked than is evident at first sight. This is especially evident in visual space perception; actions are performed in space and are guided and controlled by objects in spatial positions. Here we shortly introduce the three research camps dealing with the relationship between space perception and action: the ecological camp, the two‐visual‐systems camp, and the constructivist camp. We show that these camps emphasize and open different theoretical and empirical perspectives, but that they can be seen to complement each other. We end with an overview of the papers in this special issue.