McCourt M E, Olafson C
Department of Psychology, North Dakota State University, Fargo 58105-5075, USA.
Neuropsychologia. 1997 Mar;35(3):369-80. doi: 10.1016/s0028-3932(96)00143-1.
Perceptual and cognitive influences on line bisection were isolated using a tachistoscopic forced-choice paradigm. Pretransected lines were presented for 150 msec at four orientations ([symbol: see text],-,/ and [symbol: see text]). Subjects made either 'left-right' (for -,/, and [symbol: see text] lines) or 'above-below' (for [symbol: see text],/and [symbol: see text] lines) discriminations in response to each line stimulus, depending upon perceived transector location relative to veridical line midpoint. Median response time and point of subjective equality (P.S.E.) were computed for each treatment condition. P.S.E.s in 'left-right' conditions were significantly left of veridical; response time maxima were similarly displaced. Azimuthal pseudoneglect was greatest for horizontal lines. P.S.E.s in 'above-below' conditions were displaced above veridical, and response time maxima were similarly displaced. Altitudinal pseudoneglect was greatest for negative diagonal lines [symbol: see text]. Azimuthal pseudoneglect significantly exceeded altitudinal pseudoneglect. 'Left-right' responses (mean = 478.3 msec) were significantly faster than 'above-below' responses (mean = 504.6 msec). We conclude that scanning eye and/or gross limb movements do not account for pseudoneglect, and that a significant component must be purely perceptual. Chronometric and psychometric measures of pseudoneglect are in remarkable agreement. The effects of altitudinal and azimuthal pseudoneglect are neither separable nor additive, suggesting the existence of independent mechanisms governing the allocation of spatial attention to objects of differing orientation. The slopes of the psychometric functions for lines of cardinal orientation are significantly steeper than for diagonal lines, which may reflect a processing conflict between these putatively independent mechanisms at diagonal line orientations. Decision context significantly modulates the magnitude of pseudoneglect for physically identical stimuli, perhaps reflecting the selective differential engagement of the vertical or horizontal attentional mechanisms. There are significant individual differences in line bisection performance, even in a very homogeneous sample of strongly right-handed subjects.
采用速示强迫选择范式分离了知觉和认知对线平分的影响。将预先截断的线以四种方向（[符号：见原文]、-、/和[符号：见原文]）呈现150毫秒。根据相对于真实线段中点的感知截断位置，受试者对每个线段刺激做出“左-右”（对于-、/和[符号：见原文]线段）或“上-下”（对于[符号：见原文]、/和[符号：见原文]线段）的辨别。计算每种处理条件下的中位反应时间和主观相等点（P.S.E.）。“左-右”条件下的P.S.E.显著位于真实中点的左侧；反应时间最大值也有类似的偏移。水平线段的方位性假性忽视最为明显。在‘上-下’条件下，P.S.E.位于真实中点上方，反应时间最大值也有类似的偏移。负对角线[符号：见原文]的高度性假性忽视最为明显。方位性假性忽视显著超过高度性假性忽视。“左-右”反应（平均=478.3毫秒）显著快于“上-下”反应（平均=504.6毫秒）。我们得出结论，扫视眼动和/或粗大肢体运动不能解释假性忽视，并且一个重要成分必须是纯粹的感知性的。假性忽视的计时和心理测量指标高度一致。高度性和方位性假性忽视的影响既不可分离也不可相加，这表明存在独立的机制来控制对不同方向物体的空间注意力分配。基本方向线段的心理测量函数斜率显著陡于对角线，这可能反映了在对角线方向上这些假定独立机制之间的加工冲突。决策背景显著调节了对物理上相同刺激的假性忽视程度，这可能反映了垂直或水平注意力机制的选择性差异参与。即使在非常同质的强右利手受试者样本中，线平分表现也存在显著的个体差异。
