Andreassi J L, Juszczak N M
Int J Psychophysiol. 1984 Nov;2(2):87-95. doi: 10.1016/0167-8760(84)90002-3.
The purpose of the present study was to examine possible hemispheric differences in discriminations of line length and to determine whether the visual event related potential (ERP) recorded from over left and right hemispheres was related to performance. Twelve right-handed subjects participated on each of 2 separate days. The visual ERPs were derived from left occipital (O1) and right occipital (O2) placements. Eye blinks and vertical and lateral eye movements were also monitored. A single vertical 1.0 cm line (Standard) was displayed for 40 ms and was followed 2 s later by either a 0.9 cm, 1.0 cm or 1.1 cm (Comparison) line (also 40 ms). Subjects were asked to judge whether the second of the lines (Comparison) was "shorter" or "longer" than the first. Stimuli appeared at the center of a screen or at 1 degree 24' to the left and right of central fixation. Accuracy of line length judgements were similar in all 3 visual fields indicating a lack of hemispheric performance asymmetry for this type of discrimination task. In addition, there was no evidence of hemispheric asymmetry in the ERPs. The ambiguous discrimination involving the 1.0 cm standard and comparison lines seems to have influenced P3 latencies at both hemispheres. Namely, P3 latency was significantly longer in response to the 1.0 cm line than to the 0.9 cm or 1.1 cm lines. We propose that the ambiguous discrimination required a greater time for simulus evaluation and that this was reflected in the delayed P3 latencies.
本研究的目的是检验在直线长度辨别中可能存在的半球差异，并确定从左右半球记录的视觉事件相关电位（ERP）是否与表现相关。12名右利手受试者在两个不同的日子分别参与实验。视觉ERP来自左枕叶（O1）和右枕叶（O2）位置。同时也监测眨眼以及眼球的垂直和水平运动。一条1.0厘米长的垂直单线（标准线）显示40毫秒，2秒后接着显示一条0.9厘米、1.0厘米或1.1厘米长的（比较线）（同样40毫秒）。受试者被要求判断第二条线（比较线）比第一条线“短”还是“长”。刺激出现在屏幕中央或中央注视点左右1度24分的位置。在所有三个视野中，直线长度判断的准确性相似，表明对于这种类型的辨别任务不存在半球表现不对称。此外，ERP中也没有半球不对称的证据。涉及1.0厘米标准线和比较线的模糊辨别似乎影响了两个半球的P3潜伏期。也就是说，对1.0厘米线的反应中P3潜伏期明显长于对0.9厘米或1.1厘米线的反应。我们认为，模糊辨别需要更长时间进行刺激评估，这在延迟的P3潜期中得到了体现。
