Perception Of Peripersonal Space Research Articles

Visual perspective, distance, and felt presence of others in dreams

The peripersonal space, that is, the limited space surrounding the body, involves multisensory coding and representation of the self in space. Previous studies have shown that peripersonal space representation and the visual perspective on the environment can be dramatically altered when neurotypical individuals self-identify with a distant avatar (i.e., in virtual reality) or during clinical conditions (i.e., out-of-body experience, heautoscopy, depersonalization). Despite its role in many cognitive/social functions, the perception of peripersonal space in dreams, and its relationship with the perception of other characters (interpersonal distance in dreams), remain largely uncharted. The present study aimed to explore the visuospatial properties of this space, which is likely to underlie self-location as well as self/other distinction in dreams. 530 healthy volunteers answered a web-based questionnaire to measure their dominant visuo-spatial perspective in dreams, the frequency of recall for felt distances between their dream self and other dream characters, and the dreamers’ viewing angle of other dream characters. Most participants reported dream experiences from a first-person perspective (1PP) (82%) compared to a third-person perspective (3PP) (18%). Independent of their dream perspective, participants reported that they generally perceived other dream characters in their close space, that is, at distance of either between 0 and 90 cm, or 90–180 cm, than in further spaces (180–270 cm). Regardless of the perspective (1PP or 3PP), both groups also reported more frequently seeing other dream characters from eye level (0° angle of viewing) than from above (30° and 60°) or below eye level (−30° and −60°). Moreover, the intensity of sensory experiences in dreams, as measured by the Bodily Self-Consciousness in Dreams Questionnaire, was higher in individuals who habitually see other dream characters closer to their personal dream self (i.e., within 0–90 cm and 90–180 cm). These preliminary findings offer a new, phenomenological account of space representation in dreams with regards to the felt presence of others. They might provide insights not only to our understanding of how dreams are formed, but also to the type of neurocomputations involved in self/other distinction.

Refraining from interaction can decrease fear of physical closeness during COVID-19

Perception of peripersonal space (PPS) and interpersonal distance (IPD) has been shown to be modified by external factors such as perceived danger, the use of tools, and social factors. Especially in times of social distancing in the context of the COVID-19 pandemic, it is vital to study factors that modify PPS and IPD. The present work addresses the question of whether wearing a face mask as a protection tool and social interaction impact the perception of IPD. We tested estimated IPD in pictures at three distances: 50 cm, 90 cm, and 150 cm in both social interaction (shaking hands) and without interaction and when the two people in the pictures wore a face mask or not. Data from 60 subjects were analyzed in a linear mixed model (on both difference in distance estimation to the depicted distance and in absolute distance estimation) and in a 3 (distance: 50, 90, 150) × 2 (interaction: no interaction, shake hands), × 2 face mask (no mask, mask) rmANOVA on distance estimation difference. All analyses showed that at a distance of 50 and 90 cm, participants generally underestimated the IPD while at an IPD of 150 cm, participants overestimated the distance. This could be grounded in perceived danger and avoidance behavior at closer distances, while the wider distance between persons was not perceived as dangerous. Our findings at an IPD of 90 cm show that social interaction has the largest effect at the border of our PPS, while the face mask did not affect social interaction at either distance. In addition, the ANOVA results indicate that when no social interaction was displayed, participants felt less unsafe when depicted persons wore a face mask at distances of 90 and 150 cm. This shows that participants are on the one hand aware of the given safety measures and internalized them; on the other hand, that refraining from physical social interaction helps to get close to other persons.

Sensori-motor adaptation to novel limb dynamics influences the representation of peripersonal space

Peripersonal space can be considered as the interface between the body and the environment, where objects can be reached and which may serve as a reference for the central nervous system with regard to possible actions. Peripersonal space can be studied by assessing the perception of the reachable space, which depends on the body's physical characteristics (i.e., arm length) since their modifications have been shown to be associated with a change in peripersonal space representation. However, it remains unclear whether the representation of limb dynamics also influences the representation of peripersonal space. The present study investigated this issue by perturbing the force-field environment. A novel force field was created by rotating an experimental platform where participants were seated while they reached towards visual targets. Manual reaching performance was assessed before, during and after platform rotation. Crucially, perception of peripersonal space was also assessed, with reachability judgments, before and after platform rotation. As expected, sensori-motor adaptation to the perturbed force field was observed. Our principal finding is that peripersonal space was systematically perceived as closer to the body after force-field adaptation. Two control experiments showed no significant difference in reachability judgments when no reaching movements were performed during platform rotation or when reaching movements were performed without platform rotation, suggesting that the change in perceived peripersonal space resulted from exposure to new limb dynamics. Overall, our findings show that sensori-motor adaptation of reaching movements to a new force field, which does not directly influence arm length but results in the updating of the arm's internal model of limb dynamics, interacts with the perceptual categorisation of space, supporting a motor contribution to the representation of peripersonal space.

Neuroergonomic analysis of perihand space: effects of hand proximity on eye-tracking measures and performance in a visual search task

ABSTRACTAccording to recent studies, cognitive processes are modulated by the proximity of the hands to a stimulus. Specifically, hand proximity (also known as nearby-hand or hand-presence effects) induces a bias to process information near the hands more precisely and this effect can be facilitative or debilitative depending on the task context. Two different distances of the hands in reference to the screen were studied as independent variables: hands placed on the screen and hands placed on the lap. The dependent variables were search times and different eye-tracking parameters. Given the age-related decline in the perception of peripersonal space, the results were analysed for two different age groups. Overall, we found a more detailed evaluation of information near the hands depending on age. In conclusion, the study presents a cognitive behavioural evaluation of human–computer interaction which can be used for touchscreen interface and interaction design as well as modelling human–system interaction.

Proprioceptively guided reaching movements in 3D space: effects of age, task complexity and handedness.

Aging is associated with impaired upper limb proprioceptive acuity, as reflected by decreased position matching accuracy with increasing task complexity and movement extent. Most studies have primarily used single-joint or planar paradigms to examine age-related changes in proprioception. It is unclear whether these changes can be generalized to more complex multi-joint movements, where additional sensory feedback may affect performance. Since age-related declines in cognitive function may impair the ability to integrate multiple sources of sensory feedback, deficits in position matching ability in older adults may persist when tasks are performed in three-dimensional space. The accuracy with which young and older participants reproduced remembered reference hand positions was assessed under different experimental conditions. Participants matched target locations located directly to the front or 45° to the side relative to the midline using the preferred and non-preferred arms. Either the same (i.e., ipsilateral matching) or the opposite (i.e., contralateral matching) arm was used to reproduce the target location. No differences in matching accuracy were found between young and older participants when matching ipsilaterally. When matching contralaterally, accuracy was worse in older participants for target locations located to the side, which may reflect age-related changes in the perception of peripersonal space. In contrast to previous studies, accuracy did not differ between the preferred and non-preferred arms in either group. These results extend previous findings demonstrating age-related impairments in proprioceptively guided arm movements when interhemispheric transfer is required.

Représentation de l’espace péripersonnel chez les enfants de 7 à 14 ans

Peripersonal space is defined as the space containing the objects that can be manually reached without the necessity for prior displacement of the whole body. The perception of its boundary requires combining distance-related visual information with representations of action possibilities with the body. In children, it has been shown that the capabilities of multisensory and sensorimotor integration during development are not optimal before the age of 8 to 10years. In this context, our study aims at measuring in children 7 to 14years, the perception of peripersonal space in different conditions of presentation of visual stimuli. The results show that children ages 7 and 8 overestimate their peripersonal space more than older children and appear more affected by the conditions of presentation of the visual stimuli. A major change is observed between 8 and 10years, suggesting that at this age, the development of new perceptual competences involving motor representations.

The perception of peripersonal space in right and left brain damage hemiplegic patients

Peripersonal space, as opposed to extrapersonal space, is the space that contains reachable objects and in which multisensory and sensorimotor integration is enhanced. Thus, the perception of peripersonal space requires combining information on the spatial properties of the environment with information on the current capacity to act. In support of this, recent studies have provided converging evidences that perceiving objects in peripersonal space activates a neural network overlapping with that subtending voluntary motor action and motor imagery. Other studies have also underlined the dominant role of the right hemisphere (RH) in motor planning and of the left hemisphere (LH) in on-line motor guiding, respectively. In the present study, we investigated the effect of a right or left hemiplegia in the perception of peripersonal space. 16 hemiplegic patients with brain damage to the left (LH) or right (RH) hemisphere and eight matched healthy controls performed a color discrimination, a motor imagery and a reachability judgment task. Analyses of response times and accuracy revealed no variation among the three groups in the color discrimination task, suggesting the absence of any specific perceptual or decisional deficits in the patient groups. In contrast, the patient groups revealed longer response times in the motor imagery task when performed in reference to the hemiplegic arm (RH and LH) or to the healthy arm (RH). Moreover, RH group showed longer response times in the reachability judgment task, but only for stimuli located at the boundary of peripersonal space, which was furthermore significantly reduced in size. Considered together, these results confirm the crucial role of the motor system in motor imagery task and the perception of peripersonal space. They also revealed that RH damage has a more detrimental effect on reachability estimates, suggesting that motor planning processes contribute specifically to the perception of peripersonal space.

Rôle des propriétés inertielles segmentaires sur la perception de l’étendue de l’espace péripersonnel

Previous studies have suggested that the perception of peripersonal space can hardly be achieved using only scene-based visual cues and requires combining visual information with motor representations. Motor representation can be viewed as a component of a predictive system, which includes a neural process that simulates through motor imagery the dynamic behaviour of the body in relation to the environment. In this study, we analysed whether modifying the force required to reach a visual target influences the perception of what is reachable. In a visuomotor task, the experimental group ( n = 10) adapted to a 1.5 kg weight attached to the right wrist while performing a series of pointing movements. The control group ( n = 10) performed the motor task without inertial perturbation. A perceptual judgement task of what is reachable was performed before and after the motor task. Results showed that inertial perturbation produced initially an undershoot of the target suggesting a lack of motor force to overcome the inertial perturbation, but spatial errors receded progressively through movement rehearsal. Perceptual estimates of what is reachable slightly overestimated action capacities but were not affected by motor adaptation. Thus, modifying motor force required to compensate for inertial perturbation had no direct effect on the perception of peripersonal space. When interpreted in regard to previous experimental work, this result suggests that motor representations may provide information about the sensory or spatial consequences of action rather than the sense of effort associated with motor production.

Dynamic spatial cognition: Components, functions, and modifiability of body schema1

Abstract: There has been substantial progress towards the understanding of the classical notion of “body schema,” with recent advances in experimental methodology and techniques. Mental rotation of the hands can be used as a tool to investigate body schema. Research has shown that implicit motor imagery (i.e., mental simulated movements) can be generated based on the body schema, by combining both stored and incoming sensory information. Multimodal stimulation of peripersonal space has also served as an experimental paradigm for the study of body schema. Perception of peripersonal space is based on body‐part‐centered space coding that is considered as a manifestation of the body schema, its function being to integrate visual, tactile, and proprioceptive information, and perhaps motor plans as well. By combining such experimental paradigms with neuroimaging and neurophysiological techniques, research has converged to show that the parietal association cortex and premotor cortex are important for the body schema. Multimodal perception of body parts and peripersonal space have been also studied in relation to prism adaptation and tool use effects, indicating a clear modifiability of the body schema. Following prolonged adaptation to reversed vision, a reversed hand representation can be added to the body schema like a tool. The stored component of the body schema may not be established well in young children. But once established it may not be deleted even after an arm is amputated, although it may be weakened. All of these findings help to specify properties of the body schema, its components, functions, and modifiabilities.

Problems with perception of space in Parkinson’s disease: a questionnaire study

A questionnaire was completed by 197 putative sufferers from Parkinson’s disease (PD), 43 sufferers from rheumatoid arthritis (RA), and 73 normal age-matched controls. The study built on earlier work to explore further the PD sufferer’s experience of perceptual problems, especially changes in visual perception of the environment. The responses of the RA group allowed investigation of the possibility that any reported problems in the PD group resulted from a chronic and debilitating illness which affects the motor systems, rather than from Parkinson’s disease per se. The control and RA groups differed only on those questions that implicated motor problems (such as reaching for objects). The results suggest that, although the PD respondents are not abnormal in, for example, their descriptions of their own body image or judging the distance between nearby objects, they do notice significant changes in their perception of the world around them, reporting problems with judging distance and motion in the street and problems reaching for objects and moving through narrow spaces within the home. Finally, a factor analysis of the PD responses suggested that they grouped on four main factors, one relating to the motor symptoms of the disease, the second to the perception of peripersonal space, the third to retinal changes, and the fourth to the type of medication. The results of the study suggest visuospatial deficits in PD which may involve the parietal lobe and have implications for understanding the way in which PD patients interact with their environment.