Consciousness is, perhaps, the aspect of our mental lives that is the most perplexing for both psychologists and philosophers. Daniel Dennett has described it as 'both the most obvious and the most mysterious feature of our minds' and attempts at definition often seem to move in circles. Thomas Nagel famously remarked that 'without consciousness the mind-body problem would be much less interesting. With consciousness it seems hopeless.'. These observations might suggest that consciousness - indefinable and mysterious - falls outside the (...) scope of rational enquiry, defying both scientific and philosophical investigation. In reality, however, the topic has been a focus of psychological investigation since William James and is increasingly vital in philosophical research. This book illustrates the various, interdisciplinary approaches to the problem, providing both pointers to a solution and a summary of the key positions. (shrink)

Category-specific impairments of object recognition and naming are among the most intriguing disorders in neuropsychology, affecting the retrieval of knowledge about either living or nonliving things. They can give us insight into the nature of our representations of objects: Have we evolved different neural systems for recognizing different categories of object? What kinds of knowledge are important for recognizing particular objects? How does visual similarity within a category influence object recognition and representation? What is the nature of our semantic knowledge (...) about different objects? We review the evidence on category-specific impairments, arguing that deficits even for one class of object cannot be accounted for in terms of a single information processing disorder across all patients; problems arise at contrasting loci in different patients. The same apparent pattern of impairment can be produced by damage to different loci. According to a new processing framework for object recognition and naming, the hierarchical interactive theory, we have a hierarchy of highly interactive stored representations. HIT explains the variety of patients in terms of lesions at different levels of processing and different forms of stored knowledge used both for particular tasks and for particular categories of object. Key Words: category-specific deficits; functional imaging; hierarchical models; interactive activation models; neuropsychology; object recognition; perceptual and functional knowledge. (shrink)

We present work demonstrating that the nature of an object for our visual system depends on the actions we are programming and on the presence of action relations between stimuli. For example, patients who show visual extinction are more likely to become aware of two objects if the objects fall in appropriate visual locations for a common action. This effect of the action relations between objects is modulated both by the familiarity of the positioning of the objects for action, and (...) by the mere possibility of action (the ‘affordance’) between the objects. In addition, the programming of an action to a part of an object alters the representation of that object, making the ‘part’ into the object selected by the visual system. These results point to object coding being a rather flexible process, affected not only by the perceptual properties of stimuli but also by the relations between these properties and action. We discuss the implications for theories of perception as well as considering why action information, in particular, may be important for perception. (shrink)

To generate coherent behaviour, the brain needs to attend selectively to the many objects that are present in the environment, but this poses several questions. How does the brain know which objects 'belong together'? How does the information from different senses get combined? How does this help to plan and carry out actions? The subject of attentional mechanisms has a long history in cognitive psychology, as it is the key to making sense of the visual world. However, new developments in (...) cognitive neuroscience, and greater understanding of how attention and action are integrated, have transformed the field. This book is the first to bring together leading researchers to discuss the convergence of experimental findings in the following areas: Visual selective attention Attention and perceptual integration Spatial representation and attention Visual attention and action Control of attention Attention, Space, and Action provides a unique combination of perspectives that will appeal to students and researchers from psychology, neuropsychology, neurophysiology, and neuroanatomy. (shrink)

Evidence from visual-search experiments is discussed that indicates that there is spatially parallel encoding based on three-dimensional (3-D) spatial relations between complex image features. In one paradigm, subjects had to detect an odd part of cube-like figures, formed by grouping of corner junctions. Performance with cube-like figures was unaffected by the number of corner junctions present, though performance was affected when the corners did not configure into a cube. It is suggested from the data that junctions can be grouped to (...) form 3-D shapes in a spatially parallel manner. Further, performance with cube-like figures was more robust to noncollinearity between junctions than was performance when junctions grouped to form two-dimensional planes. In the second paradigm, subjects searched for targets defined by their size. Performance was affected by a size illusion, induced by linear-perspective cues from local background neighbourhoods. Search was made more efficient when the size illusion was consistent with the real size difference between targets and nontargets, and it was made less efficient when the size illusion was inconsistent with the real size difference. This last result occurred even though search was little affected by the display size in a control condition. We suggest that early, parallel visual processes are influenced by 3-D spatial relations between visual elements, that grouping based on 3-D spatial relations is relatively robust to noncollinearity between junctions, and that, at least in some circumstances, 3-D relations dominate those coded in two-dimensions. (shrink)

Earlier work has demonstrated that attention is indirectly cognitively malleable by processes of self-association – processes by which agents explicitly associate an item with the self. We extend this work by considering the manipulation of attention to both salient and non-salient objects. We demonstrate that self-association impacts attentional processing not only of non-salient objects, but also regarding salient items known to command attention. This result indicates the flexibility and susceptibility of attentional processing to cognitive manipulation.

Prior work shows that the possibility of action to an object facilitates attentional deployment. We sought to investigate the neural mechanisms underlying this modulation of attention by examining ERPs to target objects that were either congruently or incongruently gripped for their use in the presence of a congruently or incongruently gripped distractor. Participants responded to the presence or absence of a target object matching a preceding action word with a distractor object presented in the opposite location. Participants were faster in (...) responding to congruently gripped targets compared to incongruently gripped targets. There was a reduced N2pc potential when the target was congruently gripped, and the distractor was incongruently gripped compared to the conditions where targets were incongruently gripped or when the distractor, as well as target, was congruently gripped. The N2pc results indicate that target selection is easier when action information is congruent with an object’s use. (shrink)

We discuss the difficulty of measuring the perceptual experience of colour, supporting Palmer's assertion that neuropsychological disorders of colour processing can be informative in this respect. We point out that some disorders seem to affect the perceptual experience of colour over and above the perceptual processing of colour, providing direct insights into the neural mechanisms supporting perceptual experience.

A model of when and where saccades are made necessarily incorporates a model of the “When” and “Where” of target selection. We suggest that the framework proposed by Findlay & Walker does not specify sufficiently how selection processes contribute to the spatial and temporal determinants of saccade generation. Examples from across-trial priming in visual search and from the inhibition of temporally segmented distractors show linkage between the processes involved in computing when and where selection operates, so that there is cooperation (...) rather than competition between so-called Where and When pathways. Aspects of spatial selection may also determine the remote distractor effect on saccades. The detailed relations between the processes involved in selection and saccade generation may be best understood in relation to detailed computational accounts of the processes. (shrink)

I discuss the relations between the phenomenon of inattentional blindness and neuropsychological syndromes such as visual neglect, extinction and simultanagnosia. While there are similarities in the types of unconscious processing apparent in inattentional blindness and in these syndromes, there are also differences - for instance, grouping affects the reportability of stimuli in some neuropsychological syndromes but not necessarily in inattentional blindness. The reasons for such discrepancies, and the link between unconscious processing and underlying neural structures are discussed.