Allocentric and Egocentric Spatial Attention Bias in Individuals with Right-Hemispheric Stroke and Unilateral Spatial Neglect: A Pilot Study

Background In neurorehabilitation, limited research exists on response performance and attention deficits in individuals with neglect across allocentric (aSC) and egocentric (eSC) spatial coding frameworks. These deficits are commonly assessed using pen-and-paper tests, which often fail to detect subclinical lateralized attention deficits. A computer-based task involving detecting shapes using a cue-to-target paradigm offers precise and sensitive data for identifying allocentric and egocentric spatial attention deficits. Methods This pilot study involved 18 right-handed healthy volunteers (HC) aged 23.89 ± 3.44 years, 13 individuals with right-hemispheric stroke and neglect (USN+) aged 32.83 ± 4.45 years, and 10 with stroke but no neglect (USN-) aged 32.6 ± 5.18 years, who performed a computer-based attention task. Response time (RT), accuracy rate (AR), lateralized visual perception deficits, reorienting spatial attention deficits, and disengagement deficits were recorded and analyzed. Results The USN + group had lower AR and slower RT in both aSC and eSC conditions than the USN- and HC groups across visual fields and cue types. Notably, the USN + group showed a greater RT delay for left and right visual fields (LVF) targets in the contralesional visual field than in the ipsilesional field, a pattern absent in the USN- or HC. No significant differences in AR and total RT were found between the aSC and eSC groups, but both stroke groups took longer to identify LVF targets in aSC than in eSC. Only the HC group displayed a significantly positive validity effect, with slower RT after invalid cues. This reflected their ability to disengage attention and maintain alertness. The USN + group had significantly slower RT for invalidly cued contralesional targets compared to the USN- and HC groups both in conditions. Conclusion Our study shows that individuals with neglect exhibit a rightward attentional bias during visuospatial tasks in both aSC and eSC conditions. Individuals without neglect, though classified as subclinical by pen-and-paper tests, showed a rightward bias in aSC and a leftward bias in eSC tasks using computer-based assessments. Those with or without neglect had greater difficulty with allocentric target identification in the contralesional visual field compared to egocentric processing. Additionally, individuals with neglect demonstrated a disengagement deficit, while both groups showed reorienting deficits in visuospatial attention.