Seeing the Bias: Hemifield‑Dependent Remapping of Sensory, Sighting, and Acuity Eye Dominance

Eye dominance may refer to sensory, sighting, and acuity dominance, yet their correspondence across the visual field is unclear. Here, we indexed these three dominance metrics across 17 visual field locations: the fovea and 16 locations at 3° and 6° eccentricities along eight polar angles.

Forty-three visually normal adults were tested. Sensory dominance was indexed with a dichoptic signal-in-noise motion coherence threshold task, sighting dominance with a Porta-derived pointing alignment task, and acuity dominance with a grating acuity task. Peripheral stimuli across all tasks were size scaled according to the cortical magnification function.

Along the horizontal and oblique meridians, both sensory and sighting dominance shifted from foveal dominance toward the left eye in the left hemifield and toward the right eye in the right hemifield. There were no shifts in sensory or sighting dominance along the vertical meridian. Sensory and sighting dominance were thus spatially well matched. Within subjects, sensory dominance significantly predicted sighting dominance across the visual field, and this correspondence was selective to the meridians exhibiting hemifield asymmetries. In contrast, acuity dominance was weak in magnitude and spatially invariant, with weak, nonsignificant correlations with the other two metrics.

Sensory and sighting eye dominance are not uniform across the visual field. We speculate that both tap into binocular combination processes at the primary visual cortex (V1), where the contralateral eye is weighted more strongly due to structural asymmetries across the visual pathway. In contrast, acuity dominance likely reflects monocular optical and retinal factors independent of binocular interactions, explaining its spatial invariance and weak correlations with other dominance metrics. Our results suggest that the clinical convention of relying on a single foveal test (e.g., hole-in-the-card or Porta) cannot capture an individual's dominant eye across the visual field or across sensory, sighting, and acuity dimensions.