The physiology and psychology of selective attention to touch.

In this chapter we review psychological and physiological experiments on selective attention to touch stimuli. We explore the role of selective attention in tactile target detection and search, determining those tasks that benefit from attention and those which can be effectively performed pre-attentively. We also try to determine the stage at which attentional selection occurs. We review electrophysiological and human brain imaging (PET, fMRI, MEG, SEP) studies to assess how early in the somatosensory processing pathway attentional modulation occurs. There is some evidence that the primary somatosensory cortex (S1) can show attentional effects. However, a number of studies have suggested that there is a hierarchy to attentional modulation in the somatosensory system, with the greatest effects being observed in secondary and association areas.