In this volume, three aspects are examined: a) normal subjects, where new findings on spatial behavior are described. b) brain-lesioned subjects, where the ...

Unilateral spatial neglect is a disorder characterized by the failure to report, respond to, or orient toward the contralateral side of space to a brain lesion. Current assessment methods often fail to discover milder forms, cannot differentiate between unilateral spatial neglect subtypes and lack ecological validity. There is also a need for treatment methods that target subtypes. Immersive virtual reality systems in combination with eye-tracking have the potential to overcome these shortcomings, by providing more naturalistic environments (...) and tasks, with sensitive and detailed measures. This systematic review examines the state of the art of research on these technologies as applied in the assessment and treatment of USN. As we found no studies that combined immersive VR and ET, we reviewed these approaches individually. The review of VR included seven articles, the ET review twelve. The reviews revealed promising results. All included studies found significant group-level differences for several USN measures. In addition, several studies found asymmetric behavior in VR and ET tasks for patients who did not show signs of USN in conventional tests. Particularly promising features were multitasking in complex VR environments and detailed eye-movement analysis. No VR and only a few ET studies attempted to differentiate USN subtypes, although the technologies appeared appropriate. One ET study grouped USN participants using individual heatmaps, and another differentiated between subtypes on drawing tasks. Regarding ecological validity, although no studies tested the prognostic validity of their assessment methods, VR and ET studies utilized naturalistic tasks and stimuli reflecting everyday situations. Technological characteristics, such as the field of view and refresh rate of the head-mounted displays, could be improved, though, to improve ecological validity. We found no studies that utilized VR or ET technologies for USN treatment up until the search date of the 26th of February 2020. In conclusion, VR-ET-based systems show great potential for USN assessment. VR-ET holds great promise for treatment, for example, by monitoring behavior and adapting and tailoring to the individual person’s needs and abilities. Future research should consider developing methods for individual subtypes and differential diagnostics to inform individual treatment programs. (shrink)

Spatial neglect is a disorder of space-related behaviour. It is characterized by failure to explore the side of space contralateral to a brain lesion, or to react or respond to stimuli or subjects located on this side. Research on spatial neglect and related disorders has developed rapidly inrecent years. These advances have been made as a result of neuropsychological studies of patients with brain damage, behavioural studies of animal models, as well as through functional neurophysiological experiments (...) and functional neuroimaging.The Cognitive and Neural Bases of Spatial Neglect provides an overview of this wide-ranging field of scientific endeavour, providing a cohesive synthesis of the most recent observations and results. As well as being a fascinating clinical phenomenon, the study of spatial neglect helps us tounderstand normal mechanisms of directing and maintaining spatial attention and is relevant to the contemporary search for the cerebral correlates of conscious experience, voluntary action and the nature of personal identity itself.The book is divided into seven sections covering the anatomical and neurophysiological bases of the disorder, frameworks of neglect, perceptual and motor factors, the relation to attention, the cognitive processes involved, and strategies for rehabilitation.Chapters have been written by a team of the leading international experts in this field.This will be essential reading for neuropsychologists, neurologists, neurophysiologists, cognitive neuroscientists and psychologists. (shrink)

Patients may show a more-or-less complete deviation of the head and eyes towards the right (ipsilesional) side [that is, to the same side of egocentric space as the brain lesion responsible for their disorder]. If addressed by the examiner from the left (contralesional) side [the opposite side to their lesion], patients with severe extrapersonal neglect may fail to respond or may look for the speaker in the right side of the room, turning head and eyes more and more to (...) the right. Frequently these patients will not pick up food from the left half of the plate. Given a crossword puzzle, they may complete only the squares to the right. If walking is not prevented by hemiparesis, neglect patients may lose their bearings, since they do not make use of left sided cues. (shrink)

We describe some of the signs and symptoms of left visuo-spatial neglect. This common, severe and often long-lasting impairment is the most striking consequence of right hemisphere brain damage. Patients seem to (over-)attend to the right with subsequent inability to respond to stimuli in contralesional space. We draw particular attention to how patients themselves experience neglect. Furthermore, we show that the neglect patient's loss of awareness of left space is crucial to an understanding of the condition. (...) Even after left space has been brought into the patient's consciousness (either by local cueing on the left or by an emphasis on global properties of the scene as a whole), this awareness of left space rapidly declines. We suggest that much of the symptomology of left neglect can be interpreted as a disconnection between brain mechanisms that are relatively specialized for local (detail) visual processing and global (panoramic) processing. This failure of communication between functional (subpersonal) mechanisms then has consequences for how perceptual and representational content enters into awareness. Failure of the local contents of left space to be consciously accessed is, in turn, an important aspect of why left neglect is so difficult to remediate. Patients can ''know'' that they have neglect but are cut off from the perceptual awareness that would enable them to overcome their attentional bias to the right. (shrink)

Hemispatial neglect in imagery implies a spatially organised representation. Reaction times in memory for arrays of locations from shifted viewpoints indicate processes analogous to actual bodily movement through space. Behavioral data indicate a privileged role for this process in memory. A proposed spatial mechanism makes contact with direct recordings of the representations of location and orientation in the mammalian brain.

Studies on the syndrome called ‘unilateral visual or spatial neglect’ have been used by philosophers in discussions concerning perceptual phenomenology. Nanay , based on spatial neglects studies, argued that the property of being suitable for action is part of the perceptual phenomenology of neglect patients. In this paper, I argue that the studies on visual neglect conducted thus far do not support Nanay’s thesis that when patients succeed in detecting the neglected object, it’s action properties (...) are part of their perceptual phenomenology; instead, the support the view that the patients consciously see low-level properties such as color and shape. In the first section, I discuss unilateral neglect and extinction. In the second section, I analyze Nanay’s argument. In the third section, I explain why Nanay’s thesis does not follow from the studies on visual neglect. Nanay argues that when neglect patients are cued with an action-property of an object and succeed in perceiving the object in the contralesional side they are phenomenally aware of an action-property of it but they are not phenomenally aware of its low-level properties. Since the patients detect the object, they must be phenomenally aware of some of its properties. Failing to see the low-level properties, the patients should be phenomenally aware is the action-property. Against this, I argue that research on spatial neglect shows that the patients come to see the low-level properties. I also explain why my discussion also supports the more general claim that the studies on neglect and extinction conducted thus far do not establish that the action-properties are part of the patients’ phenomenology. Finally, in section four, I examine a possible objection against my account. My arguments do not entail that the action properties are not part of perceptual phenomenology; only that the neglect studies do not establish this. (shrink)

Open peer commentary on the article “Towards a PL-Metaphysics of Perception: In Search of the Metaphysical Roots of Constructivism” by Konrad Werner. Upshot: Key aspects of Werner’s concerns involve overcoming dualisms. This presupposes an implicit spatial preunderstanding that is neglected in Werner and needs amplification. Diametric and concentric spatial-relational frames for cognition and perception offer a supporting framework for Werner’s interrogation of constructivist roots, to go beyond Cartesian metaphysics and to concretise difference that is not mere dualistic separation.

I highlight a neglected but striking phenomenological fact about our experiences: they have a pervasively spatial character. Specifically, all (or almost all) phenomenal qualities – roughly, the introspectible, philosophically puzzling properties that constitute ‘what it’s like’ to have an experience – introspectively seem instantiated in some kind of space. So, assuming a very weak charity principle about introspection, some phenomenal qualities are instantiated in space. But there is only one kind of space – the ordinary space occupied by familiar (...) objects. And the only objects appropriately located in ordinary space are outside the subject’s mind. This entails experiential externalism, the view that at least one phenomenal quality is instantiated outside the subject’s mind. Experiential externalism is incompatible with many leading theories of experience, including certain mental paint theories; some forms of representationalism; paradigmatic versions of sense-datum theory; and views on which no phenomenal qualities are instantiated. My argument is structurally similar to familiar arguments based on the ‘transparency of experience.’ However, I suggest, phenomenological intuitions about spatiality are considerably more stable than phenomenological intuitions about transparency. For many philosophers, transparency intuitions fade markedly with respect to non-standard experiences, including experiences associated with blurry or double vision. But spatiality intuitions remain robust even for these experiences. Thus, spatiality intuitions should be more dialectically effective than transparency intuitions for supporting experiential externalism. (shrink)

Encoding sensory events entails processing of several physical attributes. Is the processing of any of these attributes a pre-requisite of conscious awareness? This selective review examines a recent set of behavioral and event-related potentials, studies conducted in patients with visual and auditory unilateral neglect or extinction, with the aim of establishing what aspects of initial processing are impaired in these patients. These studies suggest that extinguished visual stimuli excite the sensory cortices, but perhaps to a lesser degree than acknowledged (...) stimuli do. However, encoding spatial attributes of auditory and visual stimuli appear to be preferentially impaired. In light of results from patients with other neuro-behavioral deficits, it is argued that egocentric spatial information is an essential pre-requisite for knowing that an external event occurred. In contrast, information handled by mostly domain-specific circuits, such as in the ventral temporal lobe, supports awareness of the identity of a stimulus, but not of its mere presence. Without spatial information, the stimulus identity will remain implicit. (shrink)

How do people reason about spatial relations? Do people with different cultural backgrounds differ in how they reason about space? The aim of our cross-cultural study on spatial reasoning is to strengthen this link between spatial cognition and culture. We conducted two reasoning experiments, one in Germany and one in Mongolia. Topological relations, such as “A overlaps B” or “B lies within C”, were presented to the participants as premises and they had to find a conclusion that (...) was consistent with the premises. The problem description allowed multiple possible “conclusions”. Our results, however, indicate that the participants had strong preferences: They consistently preferred one of the possible conclusions and neglected other conclusions, although they were also logically consistent with the premises. The preferred and neglected conclusions were similar in Germany and Mongolia. We argue that the preferences are caused by universal cognitive principles that work the same way in the western culture and Mongolia. (shrink)