Mechanisms of selective attention are vital for coherent perception and action. Recent advances in cognitive neuroscience have yielded key insights into the relationship between neural mechanisms of attention and eye movements, and the role of frontal and parietal brain regions as sources of attentional control. Here we explore the growing contribution of reversible neurodisruption techniques, including transcranial magnetic stimulation and microelectrode stimulation, to the cognitive neuroscience of spatial attention. These approaches permit unique causal inferences concerning the relationship between neural processes (...) and behaviour, and have revealed fundamental mechanisms of attention in the human and animal brain. We conclude by suggesting that further advances in the neuroscience of attention will be facilitated by the combination of neurodisruption techniques with established neuroimaging methods. (shrink)
Adaptation to right-shifting prisms improves left neglect for mental number line bisection. This study examined whether adaptation affects the mental number line in normal participants. Thirty-six participants completed a mental number line task before and after adaptation to either: left-shifting prisms, right-shifting prisms or control spectacles that did not shift the visual scene. Participants viewed number triplets (e.g. 16, 36, 55) and determined whether the numerical distance was greater on the left or right side of the inner number. Participants demonstrated (...) a leftward bias (i.e. overestimated the length occupied by numbers located on the left side of the number line) that was consistent with the effect of pseudoneglect. The leftward bias was corrected by a short period of visuomotor adaptation to left-shifting prisms, but remained unaffected by adaptation to right-shifting prisms and control spectacles. The findings demonstrate that a simple visuomotor task alters the representation of space on the mental number line in normal participants. (shrink)
Mechanisms of attention play a crucial role in filtering sensory inputs from the external world, allowing information to be prioritised for goal directed behaviour. To what extent might these same capacity-limited processes influence grapheme-colour synaesthesia, in which letters, numbers or words evoke concurrent experiences of colour? Asking synaesthetes themselves whether attention seems important in their experiences has provided a range of answers. On the one hand, for some synaesthetes, diverting attention can diminish the quality of their synaesthetic colours. On the (...) other, there are suggestions that synaesthetic experiences can themselves alter the manner in which attention is allocated to sensory stimuli in the environment. Here, we review a range of empirical investigations that have examined the role of attention in grapheme-colour synaesthesia. A particular focus of these studies has been the extent to which an inducing stimulus - such as an achromatic letter or digit - must be attended or consciously perceived to trigger a concurrent synaesthetic experience. In most cases, limiting attention or masking inducers tends to reduce or eliminate behavioural evidence of synaesthetic experiences. We also discuss how synaesthesia might improve performance in visual search tasks through post-attentive processes such as grouping, or by facilitating decision-making processes. (shrink)
The taxonomy proposed by Pessoa et al. should be extended to include “pathological” completion phenomena in patients with unilateral brain damage. Patients with visual field defects (hemianopias) may “complete” whole figures, while patients with parietal lobe damage may “complete” partial figures. We argue that the former may be consistent with the brain “filling-in” information, and the latter may be consistent with the brain ignoring the absence of information.