Many projects are ongoing in the laboratory and include studies of the neural and cognitive mechanisms that:
  • support the visual perception of space and objects as unitary wholes in experience.

  • represent the spatial relationships between objects and object parts

  • guide spatial attention, visual search and feature integration (binding)

  • produce interactions between perceptual organization and attention

  • can account for hemispheric differences in spatial representations and global/local or part/whole processing

  • can account for neuropsychological deficits such as unilateral neglect, unilateral extinction, prosopagnosia and other visual-spatial deficits

  • can account for several congenital abnormalities in visual-spatial processing such as observed in synesthesia and congenital prosopagnosia (face blindness).

  • My students and I use a variety of subject populations, cognitive tasks and methods to address these issues. Many studies test well-screened neurological patients with well-demarcated lesions to determine what areas of the brain are necessary to perform certain cognitive functions. Other studies test neurological patients based on behavioral criterion such as the loss of space or face perception. We often test different types of patients to gather converging evidence concerning particular questions. For instance, our work with focal lesion groups showing global/local differences with damage centered in the right or left posterior cortex (Robertson, Lamb & Knight, 1988) was later supported by converging evidence from "split-brain" subjects (Robertson, Lamb & Zaidel, 1993).

    To address a different question concerning visual search and feature binding we tested patients with unilateral visual neglect showing that preattentive processing during visual search ("pop out") is relatively intact, while searching for a conjunction of features, which requires binding, is severely affected (Eglin, Robertson & Knight, 1989). These findings were supported by studies with a rare patient with bilateral parietal lobe lesions and Balint's syndrome (where there is basically no there there) have supported the link between spatial awareness, spatial attention and feature integration (Friedman-Hill, Robertson & Treisman, 1995). Visual search for isolated features remains intact, while conjunction search is nearly impossible. These studies have generated several questions that are currently being addressed with functional MRI as well as further behavioral studies. We are especially interested in neural mechanisms that support spatial representations above and below the level of spatial awareness (Kim & Robertson, 2001) as well as explicit attention to objects and space (Schendel, Robertson & Treisman, 2001; List, Schumacher, D'Esposito & Robertson, submitted).

    Other projects have focused on the formation of attentional prints to account for spatial attentions role in repetition priming (Robertson, 1996), the use of spatial frames in attentional guidance (Robertson, 1995: Rhodes & Robertson, submitted; Schendel & Robertson, 2001), mechanisms underlying congenital and acquired prosopagnosia (Robertson & Sagiv, 2004), the role of spatial attention and binding in synesthesia (Robertson & Sagiv, 2004) and the use of various versions of the Stoop task to study negative priming and attentional inhibition in clinical populations (Salo, Henik & Robertson, 2001).

    The overriding question that links projects in the laboratory together is how perceptual organization and spatial attention are related to produce what we perceive and how attention affects the selection of items on-line and subsequently for further notice.

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