Nicholls Michael E R, Beckman Emily, Churches Owen
School of Psychology, Flinders University, GPO Box 2100, Adelaide, SA, 5001, Australia.
Atten Percept Psychophys. 2016 Jul;78(5):1351-62. doi: 10.3758/s13414-016-1122-7.
Clinical neglect patients overattend to stimuli on their right, whereas the general population overattend to the left (pseudoneglect). Both phenomena are affected by viewing distance, whereby the attentional biases are attenuated as the stimulus moves from near to far space. Both are also affected by stimulus length and reduce in strength, or even reverse (the crossover effect), as length decreases. To gain an insight into the cognitive/neural mechanisms that underlie the effects of viewing distance and stimulus length, in two experiments we examined the interaction between the variables. In Experiment 1 we asked university students (n = 20) to perform a horizontal landmark bisection task with lines presented at varying lengths (1.2°, 6.3°, and 18.4° of viewing angle) and distances (450 and 1,350 mm). A crossover effect and pseudoneglect were observed for the short and the long lines, respectively. An effect of viewing distance was only observed for long lines. Experiment 2 was the same, except that the lines were rotated to form vertical lines. No crossover effect was observed for the short lines, but an upward bias was observed for the long lines. Once again, an effect of viewing distance was only apparent for the long lines. These results demonstrate that the crossover effect is not a general property of short lines and is specific to the horizontal dimension. Models of crossover therefore need to incorporate processes related to left-right asymmetries. The results also demonstrate that viewing distance only affects long lines, and that this happens irrespective of orientation. A model of viewing distance is discussed that incorporates a right hemisphere mechanism specialized for an interaction between the ventral and dorsal streams.
临床忽视患者过度关注其右侧的刺激，而普通人群则过度关注左侧（假性忽视）。这两种现象都受观察距离的影响，即随着刺激从近空间移向远空间，注意力偏差会减弱。它们还都受刺激长度的影响，并且随着长度的减小，偏差强度会降低，甚至会反转（交叉效应）。为了深入了解观察距离和刺激长度影响背后的认知/神经机制，我们在两个实验中研究了这些变量之间的相互作用。在实验1中，我们要求大学生（n = 20）对以不同长度（视角为1.2°、6.3°和18.4°）和距离（450和1350毫米）呈现的线条执行水平地标二等分任务。分别观察到短线的交叉效应和长线的假性忽视。仅在长线上观察到观察距离的影响。实验2与实验1相同，只是将线条旋转以形成垂直线条。在短线上未观察到交叉效应，但在长线上观察到向上的偏差。同样，观察距离的影响仅在长线上明显。这些结果表明，交叉效应不是短线的普遍特性，而是特定于水平维度的。因此，交叉模型需要纳入与左右不对称相关的过程。结果还表明，观察距离仅影响长线，且这种情况与方向无关。我们讨论了一个观察距离模型，该模型纳入了一种专门用于腹侧和背侧流之间相互作用的右半球机制。
