Embodied perspective-taking indicated by selective disruption from aberrant self motion

Spatial perspective-taking that involves imagined changes in one’s spatial orientation is facilitated by vestibular stimulation inducing a congruent sensation of self-motion. We examined further the role of vestibular resources in perspective-taking by evaluating whether aberrant and conflicting vestibular stimulation impaired perspective-taking performance. Participants (N = 39) undertook either an “own body transformation” (OBT)task, requiring speeded spatial judgments made from the perspective of a schematic figure, or a control task requiring reconfiguration of spatial mappings from one’s own visuo-spatial perspective. These tasks were performed both without and with vestibular stimulation by whole-body Coriolis motion, according to a repeated measures design, balanced for order. Vestibular stimulation was found to impair performance during the first minute post stimulus relative to the stationary condition. This disruption was task-specific, affecting only the OBT task and not the control task, and dissipated by the second minute post-stimulus. Our experiment thus demonstrates selective temporary impairment of perspective-taking from aberrant vestibular stimulation, implying that uncompromised vestibular resources are necessary for efficient perspective-taking. This finding provides evidence for an embodied mechanism for perspective-taking whereby vestibular input contributes to multisensory processing underlying bodily and social cognition. Ultimately, this knowledge may contribute to the design of interventions that help patients suffering sudden vertigo adapt to the cognitive difficulties caused by aberrant vestibular stimulation

Observed bodies generate object-based spatial codes

Contemporary studies of spatial and social cognition frequently use human figures as stimuli. The interpretation of such studies may be complicated by spatial compatibility effects that emerge when researchers employ spatial responses, and participants spontaneously code spatial relationships about an observed body. Yet, the nature of these spatial codes – whether they are location- or object-based, and coded from the perspective of the observer or the figure – has not been determined. Here, we investigated this issue by exploring spatial compatibility effects arising for objects held by a visually presented whole-bodied schematic human figure. In three experiments, participants responded to the colour of the object held in the figure’s left or right hand, using left or right key presses. Left-right compatibility effects were found relative to the participant’s egocentric perspective, rather than the figure’s. These effects occurred even when the figure was rotated by 90 degrees to the left or to the right, and the coloured objects were aligned with the participant’s midline. These findings are consistent with spontaneous spatial coding from the participant’s perspective and relative to the normal upright orientation of the body. This evidence for object-based spatial coding implies that the domain general cognitive mechanisms that result in spatial compatibility effects may contribute to certain spatial perspective-taking and social cognition phenomena

Fractionating the unitary notion of dissociation:disembodied but not embodied dissociative experiences are associated with exocentric perspective-taking

It has been argued that hallucinations which appear to involve shifts in egocentric perspective (e.g., the out-of-body experience, OBE) reflect specific biases in exocentric perspective-taking processes. Via a newly devised perspective-taking task, we examined whether such biases in perspective-taking were present in relation to specific dissociative anomalous body experiences (ABE) - namely the OBE. Participants also completed the Cambridge Depersonalization Scale (CDS; Sierra and Berrios, 2000) which provided measures of additional embodied ABE (unreality of self) and measures of derealization (unreality of surroundings). There were no reliable differences in the level of ABE, emotional numbing, and anomalies in sensory recall reported between the OBE and control group as measured by the corresponding CDS subscales. In contrast, the OBE group did provide significantly elevated measures of derealization ("alienation from surroundings" CDS subscale) relative to the control group. At the same time we also found that the OBE group was significantly more efficient at completing all aspects of the perspective-taking task relative to controls. Collectively, the current findings support fractionating the typically unitary notion of dissociation by proposing a distinction between embodied dissociative experiences and disembodied dissociative experiences - with only the latter being associated with exocentric perspective-taking mechanisms. Our findings - obtained with an ecologically valid task and a homogeneous OBE group - also call for a re-evaluation of the relationship between OBEs and perspective-taking in terms of facilitated disembodied experiences

Imagined own-body transformations during passive self-motion

Spatial perspective taking is a crucial social skill that underlies many of our everyday interactions. Previous studies have suggested that spatial perspective taking is an embodied process that involves the integration of both motor and proprioceptive information. Given the importance of vestibular signals for own-body perception, mental own-body imagery, and bodily self-consciousness, in the present study we hypothesized that vestibular stimulation due to passive own-body displacements should also modulate spatial perspective taking. Participants performed an own-body transformation task while being passively rotated in a clockwise or counter-clockwise direction on a human motion platform. A congruency effect was observed, reflected in faster reaction times if the implied mental body rotation direction matched the actual rotation direction of the chair. These findings indicate that vestibular stimulation modulates and facilitates mental perspective taking, thereby highlighting the importance of integrating multisensory bodily information for spatial perspective taking

Tell it to the hand: Attentional modulation in the identification of misoriented chiral objects

Research in the field of cognitive neuroscience and neuropsychology on spatial cognition and mental imagery has increased considerably over the last few decades. While at the beginning of the XX century studying imagery was considered an object of derision \u2013 a \u2015sheer bunk\u2016 (Watson, 1928) \u2013 at the present, imagery researchers have successfully developed models and improved behavioral and neurophysiological measures (e.g., Kosslyn et al., 2006). Mental rotation constituted a major advance in terms of behavioral measures sensitive to imaginative operations executed on visual representations (i.e., Shepard & Cooper, 1982). The linearity of modulation between response times and angular disparity of the images allowed a quantitative estimate of imagery processes. The experiments described in the present thesis were motivated by the intent to continue and extend the understanding of such fascinating mental phenomena. The evolution of the present work took initial steps from the adoption of a behavioral paradigm, the hand laterality judgment task, as privileged tool for studying motor imagery in healthy individuals and brain-damaged patients. The similarity with mental rotation tasks and the implicit nature of the task made it the best candidate to test hypotheses regarding the mental simulation of body movements. In this task, response times are linearly affected by the angular departures the hand pictures are shown in, as for mental rotation, and their distributions are asymmetric between left and right hands. Drawing from these task features a widely held view posits that laterality judgment of rotated hand pictures requires participants to imagine hand-arm movements, although they receive no instruction to do so (e.g., Parsons, 1987a; Parsons, 1994). In Chapter 1, I provided a review of the relevant literature on visual and motor imagery. Particular aspects of the mental rotation literature are also explored. In Chapter 2, I examined the hand laterality task and the vast literature of studies that employed this task as means to test motor imagery processes. An alternative view to the motor imagery account is also discussed (i.e., the disembodied account). In Chapter 3, I exploited the hand laterality task, and a visual laterality task (Tomasino et al., 2010) to test motor and visual imagery abilities in a group of healthy aged individuals. In Chapter 4, I described an alternative view that has been proposed by others to explain the pattern of RTs in the hand laterality task: The multisensory integration account (Grafton & Viswanathan, 2014). In this view, hand laterality is recognized by pairing information between the seen hand's visual features and the observer's felt own hand. In Chapter 5, I tested and found evidence for a new interpretation of the particular configuration of response times in the hand laterality task. I demonstrated a spatial compatibility effect for rotated pictures of hands given by the interaction between the direction of stimulus rotation (clockwise vs. counterclockwise) and the laterality of the motor response. These effects changed by following temporal dynamics that were attributed to shifts of spatial attention. In the same chapter, I conducted other psychophysics experiments that confirmed the role of spatial attention and that ruled out the view of multisensory integration as the key aspect in determining the asymmetries of the response times' distribution. In Chapter 6, I conducted a study with patients suffering from Unilateral Neglect in which they performed the hand laterality task and a visual laterality task. The findings indicated that patients failed to integrate visual information with spatially incompatible responses irrespective of the type of task, and depending on egocentric stimulus-response spatial codes. A general discussion is presented in Chapter 7

Relating spatial perspective taking to the perception of other's affordances: providing a foundation for predicting the future behavior of others

Understanding what another agent can see relates functionally to the understanding of what they can do. We propose that spatial perspective taking and perceiving other's affordances, while two separate spatial processes, together share the common social function of predicting the behavior of others. Perceiving the action capabilities of others allows for a common understanding of how agents may act together. The ability to take another's perspective focuses an understanding of action goals so that more precise understanding of intentions may result. This review presents an analysis of these complementary abilities, both in terms of the frames of reference and the proposed sensorimotor mechanisms involved. Together, we argue for the importance of reconsidering the role of basic spatial processes to explain more complex behaviors

Strategy modulates spatial perspective-taking: evidence for dissociable disembodied and embodied routes

Previous research provides evidence for a dissociable embodied route to spatial perspective-taking that is under strategic control. The present experiment investigated further the influence of strategy on spatial perspective-taking by assessing whether participants may also elect to employ a separable “disembodied” route loading on inhibitory control mechanisms. Participants(N=92)undertook both the “own body transformation”(OBT)perspective-taking task,requiring speeded spatial judgments made from the perspective of an observed figure,and a control task measuring ability to inhibit spatially compatible responses in the absence of a figure.Perspective-taking performance was found to be related to performance on the response inhibition control task,in that participants who tended to take longer to adopt a new perspective also tended to show a greater elevation in response times when inhibiting spatially compatible responses.This relationship was restricted to those participants reporting thatthey adopted the perspective of another by reversing left andright whenever confronted with a front-view figure;it was absent in those participants who reported perspective-taking by mentally transforming their spatial orientation to align with that of the figure.Combined with previously published results,these findings complete a double dissociation between embodied and disembodied routes to spatial perspective-taking,implying that spatial perspective-taking is subject to modulation by strategy,and suggesting that embodied routes to perspective-taking may place minimal demands on domain general executive functions

Use of Mental Imagery in Psychotherapy: A Critical Review

The paper presents arguments in favor of the use of mental imagery for therapeutic purposes. Several existing imagery approaches to psychotherapy are critically examined and suggestions for future inquiry are offered. The intimate relation between imagery and the affective-somatic processes is stressed

Generalisation, decision making, and embodiment effects in mental rotation: A neurorobotic architecture tested with a humanoid robot.

Mental rotation, a classic experimental paradigm of cognitive psychology, tests the capacity of humans to mentally rotate a seen object to decide if it matches a target object. In recent years, mental rotation has been investigated with brain imaging techniques to identify the brain areas involved. Mental rotation has also been investigated through the development of neural-network models, used to identify the specific mechanisms that underlie its process, and with neurorobotics models to investigate its embodied nature. Current models, however, have limited capacities to relate to neuro-scientific evidence, to generalise mental rotation to new objects, to suitably represent decision making mechanisms, and to allow the study of the effects of overt gestures on mental rotation. The work presented in this study overcomes these limitations by proposing a novel neurorobotic model that has a macro-architecture constrained by knowledge held on brain, encompasses a rather general mental rotation mechanism, and incorporates a biologically plausible decision making mechanism. The model was tested using the humanoid robot iCub in tasks requiring the robot to mentally rotate 2D geometrical images appearing on a computer screen. The results show that the robot gained an enhanced capacity to generalise mental rotation to new objects and to express the possible effects of overt movements of the wrist on mental rotation. The model also represents a further step in the identification of the embodied neural mechanisms that may underlie mental rotation in humans and might also give hints to enhance robots' planning capabilities

Cognitive Maps

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