Mimicking The Effects Of Prism Adaptation In Healthy Controls And A Single Neglect Patient Through The Use Of False Feedback
Blyth Andrew Dissertation 2009.pdf (733.0Kb)
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Prism adaptation causes profound negative aftereffects in healthy control participants and even more so in hemispatial neglect patients where it has been reported that neglect patients are not aware of the perturbation caused by the prisms. Additionally, the use of prisms on alleviating the symptoms of neglect has also been investigated (Rossetti et al., 1998). In an attempt to mimic the unaware experience of neglect in controls, participants have been introduced to a gradual increment in prism strength below the level of conscious awareness, resulting in greater aftereffects (Michel et al., 2007), a finding contradictory to that of Dewar (1971) who argued that it was the number of exposure trials at a large perturbation that induces greater aftereffects. The present study aimed to recreate greater aftereffects in participants without the use of prisms by deviating the terminal feedback line by a set amount, creating a false feedback paradigm. There were three conditions, a single group who experience a 10˚ shift of terminal feedback line from terminal position, a graded group who experienced a shift by a constant amount every point, below the level of conscious awareness, thus mimicking the multi-step group described by Michel et al. (2007) and a group that wore 10˚ prisms and received valid terminal feedback. Only knowledge of results was given as feedback. Analysis revealed no significant difference in magnitude of aftereffect at the final open loop block or overall. Finally, a neglect patient, JM, was exposed to 100 10˚ false feedback trials in an attempt to recreate the findings of Rossetti et al. (1998). Aftereffects for JM were not as large as those reported by Rossetti et al. (1998) as JM no longer suffered from neglect by the time of intervention. The usefulness for the false feedback paradigm in rehabilitating neglect is then discussed.