extinction patients not only fail to respond to the contralateral external space, but also to internally represented stimuli with patients frequently locating the details of the left side on the right side. Research and characteristics of extinction German neurologists documented clinical descriptions of extinction a century ago, but the syndrome subsequently received less systematic attention than other classical neurological syndromes in part due to the rareness of suitable theoretical ideas. Moreover, despite the dramatic loss of awareness for one side, extinction was rarely considered in discussions of the neural basis of conscious perceptual experience until recently. In extinction there is a spatially specific loss of awareness. This has been difficult to explain because so many neural pathways conventionally associated with conscious perception (including primary sensory areas) remain intact in many patients. There is also much excitement about the possibility of relating awareness to neural substrates in extinction studies. In addition to revealing the critical lesion sites associated with the various clinical manifestations of visual neglect, a key message of the current investigation is that there is a need to develop more sensitive and nuanced assessment tools to characterize the different facets of this heterogeneous syndrome. It will be important to bring laboratory tests into the clinic in an effort to identify specific cognitive functions by examining each in isolation thus combining more specific descriptions extinction with better clinical measures that isolate specific cognitive functions to yield more consistent lesion mapping results in the future. Grouping effect in extinction Neglect and extinction often present simultaneously in patients. When looking at neglect, studies have demonstrated that there is more to the spatial nature than mere primary sensory loss. Proposals of this kind have become increasingly frequent in recent years but attentional accounts for neglect are not universally popular. We can think of one primary component of neglect as involving inattention and that extinction is by no means the whole story for neglect. Extinction encapsulates a critical general principle that applies for most aspects of neglect, namely that the patient's spatial deficit is most apparent in competitive situations, where information towards the good ipsilesional side comes to dominate information that would otherwise be acknowledged towards the contralesional side. This may relate to the attentional limitation seen in neurologically healthy people. We cannot become aware of multiple targets all at once, even if our sensory systems have transduced them. This is seen in patients