Abstract
Evidence from visuospatial neglect sheds light on visual object and word recognition processes. While neglect disrupts awareness for contralesional information, there is ongoing debate about the extent of perceptual processing for the neglected portion. Despite a few reports of implicit processing of visual features in hemifield neglect, it is unclear the extent to which this information reaches awareness and at what level perceptual features are bound into an integrated representation. In this study, we tested a 68-year-old man with stimulus-based left neglect- a deficit in recognition of the left half of visual objects, regardless of their location in the visual field (Figure S1A). We performed a series of experiments manipulating single visual features (color, orientation, form), feature conjunctions, and complexity, on the left/right sides of a stimulus. Strikingly, we find that he can accurately report simple color, orientation, and form information from the left of stimuli (Figure S1B,C,D). However, he performed with characteristic difficulty in reporting complex form information, evidenced by poor object recognition and word reading. Our results show that simple visual features can be processed independently when multiple are present (Figure S1E), and dissociations can emerge between the processing of complex and simple features. At the level of visual processing consisting of a stimulus represented in spatiotopic coordinates, certain visual features (particularly complex form, Figure S1A,E) may require attention for binding into a unitary representation, while some may be accessed without attention. These results inform how coherent visual percepts are formed and reach awareness in normal perception.