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In a study described in this paper, left-neglect patients were seen to bisect horizontal lines to the right of true center, with longer lines bisected further to the right than shorter ones. This line-length effect might be explained by an increase in the rightward bias of attention, because longer lines extend further ipsilesionally. Alternatively, neglect patients might be limited in their ability to internally represent horizontal magnitudes. Patients might be oriented further rightward with longer lines because these lines have longer representation. If the line length effect occurs on lines of identical objective length, but the lines are represented differently, then central mechanisms must contribute to the orientation bias. On another study, two types of lines were constructed that were perceived by normal subjects as having different lengths, but were of identical extents. Three neglect patients bisected the lines that were perceived as longer at points further to the right than on the lines perceived as shorter. These results demonstrate that relative magnitudes of internal representations contribute to the degree of bias in neglect patients.