Neuropsychologia
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Simple reaction times (RTs) to auditory-somatosensory (AS) multisensory stimuli are facilitated over their unisensory counterparts both when stimuli are delivered to the same location and when separated. In two experiments we addressed the possibility that top-down and/or task-related influences can dynamically impact the spatial representations mediating these effects and the extent to which multisensory facilitation will be observed. Participants performed a simple detection task in response to auditory, somatosensory, or simultaneous AS stimuli that in turn were either spatially aligned or misaligned by lateralizing the stimuli. ⋯ Performance with probes, quantified using sensitivity (d'), was impaired following multisensory trials in general and significantly more so following misaligned multisensory trials. This indicates that spatial information is not available, despite being task-relevant. The collective results support a model wherein early AS interactions may result in a loss of spatial acuity for unisensory information.
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Patients with right hemisphere lesions often omit or misread words on the left side of a text or the beginning letters of single words which is termed neglect dyslexia (ND). Two types of reading errors are typically observed in ND: omissions and word-based reading errors. The prior are considered as space-based omission errors on the contralesional side of the page, while the latter can be viewed as a kind of stimulus- or word-based reading errors where leftsided parts of a single perceptual entity (the word) are neglected. ⋯ The current study investigated in a sample of right-hemisphere lesioned patients with ND vs. without ND and matched healthy control subjects the influence of head-rotation (HR) on both types of reading errors using controlled indented paragraph reading tests. Passive leftward HR significantly reduced omission errors on the left side of the text in ND, but had no effect on word-based reading errors. In conclusion egocentric manipulations like HR only appear to influence space-based attentional processes in neglect evident as omissions in paragraph reading but have no impact on those attentional processes involved in word identification evident as word-based errors in paragraph reading.