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Neglect is an attentional disorder in which patients lose awareness of one side of the visual field. These patients have an impairment in perceiving stimuli, usually in the left visual field (but sometimes the right), despite an unimpaired visual system. They therefore bias their attention in the direction of the unimpaired visual field side. This impairment can refer to processing of a real visual scene, an imagined scene or both (Bisiach and Luzzatti, 1978). More recent research suggests that members of the healthy population show a leftward spatial-attentional bias but to a lesser extent. There is evidence for this both in actual perception of a scene (Bowers and Heilman, 1980) and also in imagined scenes (McGeorge et al., 2007). Many studies have shown that this bias, known as Pseudoneglect, exists within visual perception. However, more research is necessary to determine whether Pseudoneglect also impacts mental imagery. Therefore, the first aim of this study is to determine whether pseudoneglect is present both in visual perception and in mental imagery. Many studies have demonstrated a double dissociation between neglect in perception and neglect in mental imagery, suggesting that perceptual and imaginal processing are based on separate cognitive mechanisms (Coslett, 1997; Guariglia et al., 1993). Therefore, a second aim of this study is to look at whether the cognitive mechanisms are the same or different for perceptual and imaginal pseudoneglect. This involves determining whether any bias in actual perception correlates with any bias in mental imagery for each participant. The findings in Pseudoneglect may parallel to Neglect, providing more insight into the disorder. Bartolomeo, P., D'Erme, P., & Gainotti, G. (1994). The relationship between visuospatial and representational neglect. Neurology, 44(9), 1710-1710. Bisiach, E., & Luzzatti, C. (1978). Unilateral neglect of representational space. Cortex, 14(1), 129-133. Bowers, D., & Heilman, K. M. (1980). Pseudoneglect: Effects of hemispace on a tactile line bisection task. Neuropsychologia, 18(4), 491-498. Coslett, H. B. (1997). Neglect in vision and visual imagery: a double dissociation. Brain: a journal of neurology, 120(7), 1163-1171. Guariglia, C., Padovani, A., Pantano, P., & Pizzamiglio, L. (1993). Unilateral neglect restricted to visual imagery. Nature, 364(6434), 235 McGeorge, P., Beschin, N., Colnaghi, A., Rusconi, M. L., & Della Sala, S. (2007). A lateralized bias in mental imagery: Evidence for representational pseudoneglect. Neuroscience Letters, 421(3), 259-263. |
