Senior Medical Research Scientist, Veterans Administration
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, propsopagnosia 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.
Robertson, L.C. & Sagiv, N. (Eds.) (2004). Synesthesia: Perspectives from Cognitive Neuroscience. New York: Oxford University Press.
Robertson, L.C. (2003). Space, Objects, Minds and Brains. New York: Psychology Press, Essays in Cognitive Science.
Ivry, R. & Robertson, L. C. (1998). The Two Sides of Perception. Cambridge: MIT Press, Series in Cognitive Neurosciences.
Knapp, T. J. & Robertson, L. C. (Eds.) (1986). Approaches to Cognition: Contrasts and Controversies. Hillsdale, NJ: Lawrence Erlbaum & Associates.
Selected Book Chapters:
Robertson, L.C. & Schendel, K.L. (2000). Methods and Converging Evidence in Neuropsychology. In J. Grafman (Ed.). Handbook of Neuropsychology. 2nd Edition. Elsevier.
Robertson, L.C. & Rafal, R. (2000). Disorders of visual attention. In M. Gazzaniga (Ed.). The New Cognitive Neuroscience. 2nd Edition, Cambridge: MIT Press.
Robertson, L.C. (1998). Visual attention and parietal function: Their role in object perception. In R. Parasuraman (Ed.). The Attentive Brain. Cambridge, MA: MIT Press.
Robertson, L.C. (1994) The multivariate nature of unilateral neglect. Neuropsychological Rehabilitation, 4, 199-202. (Republished as a book chapter in P.E. Hammilgan & J.C. Marshall Eds. Spatial Neglect:Position papers on theory and practice. Hillsdale NJ: Erlbaum).
Robertson, L.C. (1992). Perceptual organization and attentional search in cognitive deficits. In D. I. Margolin (Ed). Cognitive Neuropsychology in Clinical Practice, Oxford University Press.
Selected Journal Articles:
Robertson, L.C. (2003). Binding, spatial attention and perceptual awareness. Nature Reviews: Neuroscience, 4, 93-102.
Robertson, L.C., Eglin, M. & Knight, R.T. (2003) Grouping influences in unilateral visual neglect. Journal of Clinical and Experimental Neuropsychology, 25, 297-307.
Friedman-Hill, S.R., Robertson, L.C., Ungerleider, L.G. & Desimone, R. (2003). Posterior parietal cortex and the filtering of distractors. Proceedings of the National Association of Science, 100(7), 4263-4268.
Schendel, K.L. & Robertson, L.C. (2002). Using reaction time to assess unilateral neglect and extinction. Special issue: Contributions of Cognitive Neuroscience to Clinical Neuropsychology: The Role of Reaction Time-Based Studies. Journal of Clinical and Experimental Neuropsychology, 24, 941-950.
Salo, R., Henik, A., Nordahl, T.E. & Robertson, L.C. (2002). Time course of inhibition and facilitation in patients with schizophrenia. Journal of Neuropsychiatry. Vol 7(4), 283-300.
Rhodes, D.L. & Robertson, L.C. (2002). Visual field asymetries and attention in scene- based coordinates. Brain & Cognition, 50, 95-115.
Henik, A., Carter, C.S., Chaderjian, M., Kraft, L., Nordahl, T.E., Salo, R. & Robertson, L.C. (2002). Attentional control and word inhibition in schizophrenia. Psychiatry Research, 110, 137-149.
Salo, R , Henik, A., Nordahl, T.E., & Robertson, L.C. (2002). Immediate versus sustained processing in schizophrenia. Journal of the International Neuropsychology Society, 8, 794-803.
Kim, M-S. & Robertson, L.C. (2001). Implicit representations of space after bilateral parietal lobe damage. Journal of Cognitive Neuroscience, 13(9), 1-8.
Schendel, K., Robertson, L.C., & Treisman, A. (2001). Objects and their locations in exogenous cueing. Perception & Psychophysics, 63(4), 577-594.
Schendel, K., & Robertson, L.C. (in press). Using Reaction Time to Assess Patients with Unilateral Neglect and Extinction. Cognitive and Affective Behavioral Neuroscience.
Robertson, L.C. (2001). Colour my i's blue. Nature, 410, 533-534.
Robertson, L.C. & Ivry, R. (2000). Hemispheric asymmetries: Attention to visual and auditory primatives. Current Directions in Psychological Science, 9(2), 59-63.
Phan, M.L., Schendel, K.L., Recanzone, G.H. & Robertson, L.C. (2000). Auditory and visual spatial localization deficits following bilateral parietal lobe lesions in a patient with Balint's syndrome. Journal of Cognitive Neuroscience, 12:4, 583-600.
Robertson, L.C. (1999). What can spatial deficits teach us about feature binding and spatial maps? Visual Cognition, 6, 409-430 (Reprinted in M. Boucart (Ed.) The Neuroscience of Perceptual Integration, East Sussex, UK: Psychology Press Ltd.).
Robertson, L.C. (1999). Spatial frequencies as a medium for guiding attention: Reply to Lamb, Yund and Pond. Journal of Experimental Psychology: General, 128, 95-98.
Robertson, L.C. & Kim, M.S. (1998). Effects of perceived space on spatial attention. Psychological Science, 10, 76-79.
Bernstein, L.J. & Robertson, L.C. (1998). Independence between illusory conjunctions of color and motion with shape following bilateral parietal lesions. Psychological Science, 9, 167-175.
Robertson, L.C., Treisman, A., Friedman-Hill, S. & Grabowecky, M. (1997). The interaction of spatial and object pathways: Evidence from Balint's syndrome. Journal of Cognitive Neuroscience, 9, 295-317.
Salo, R., Robertson, L.C., Nordahl, T.E. & Kraft, L.W. (1997). The effects of antipsychotic medication on sequential inhibitory processes. Journal of Abnormal Psychology, 106, 639-643.
Robertson, L. C. (1996). Attentional persistence for features of hierarchical patterns. Journal of Experimental Psychology: General, 125, 227-249.
Friedman-Hill, S., Robertson, L. C. & Treisman, A. (1995). Parietal contributions to visual feature binding: Evidence from a patient with bilateral lesions.Science, 269, 853-855.
Robertson, L.C. (1995) Covert orienting biases in scene-based reference frames: Orientation priming and visual field differences. Journal of Experimental Psychology: Human Perception and Performance, 21, 707-718.
Eglin, M., Robertson, L.C., Knight, R.T. & Brugger, O. (1994) Search deficits in neglect patients are dependent on size of the visual scene. Neuropsychology,4, 451-463.
Robertson, L.C., Egly, R., Lamb, M. R. & Kerth, L. (1993) Spatial attention and cuing to global and local levels of hierarchical structure. Journal of Experimental Psychology: Human Perception and Performance, 19,471-487.
Grabowecky, M., Robertson, L.C. & Treisman, A. (1993) Preattentive processes guide visual search: Evidence from patients with unilateral visual neglect. Journal of Cognitive Neuroscience, 5, 288-302.
Carter, C.S., Robertson, L.C., Chaderjian, M.R., Celaya, L.J., Nordahl, T.E. (1992). Attentional asymmetry in schizophrenia: Controlled and automatic processes. Biological Psychiatry, 31, 909-918.
Robertson, L.C. & Lamb, M.R. (1991). Neuropsychological contributions to theories of part/whole organization. Cognitive Psychology, 23, 299-330.
Lynn C Robertson