Byth W, McMahon D, King D J
School of Psychology, Queen's University of Belfast, Northern Ireland, UK.
Perception. 2000;29(4):461-80. doi: 10.1068/p2892.
The strength of the McCollough effect (ME), a pattern-contingent colour aftereffect, has been shown to be inversely related to acetylcholine, being significantly strengthened by (anticholinergic) scopolamine and weakened by (cholinergic) physostigmine delivered before adapting to the ME stimuli. The purpose of the present study was (i) to establish whether the effect of pre-adaptation scopolamine is linearly dose-dependent and (ii) to investigate the effects of scopolamine and physostigmine delivered between adaptation and testing. In experiment 1, ten healthy male volunteers who received placebo, or 0.6 mg, 1.2 mg, or 1.8 mg scopolamine before adapting to ME stimuli showed a significant linear dose-dependence over tests repeated from 10 to 70 min after adaptation. In experiment 2 twelve male volunteers adapted to ME stimuli and then received placebo, 1.2 mg oral scopolamine, or 0.75 mg subcutaneous physostigmine. On subsequent repeated testing, strength of the ME was increased by scopolamine and decreased by physostigmine relative to placebo. Both experiments were double-blind double-dummy repeated measures. These data support the view that the ME is a product of inhibitory mechanisms in the visual system rather than processes involved in associative learning.
麦科洛效应（ME）是一种模式依赖型颜色后效，其强度已被证明与乙酰胆碱呈负相关，在适应ME刺激之前给予（抗胆碱能的）东莨菪碱会显著增强该效应，而给予（胆碱能的）毒扁豆碱则会使其减弱。本研究的目的是：（i）确定适应前给予东莨菪碱的效应是否呈线性剂量依赖性；（ii）研究在适应和测试之间给予东莨菪碱和毒扁豆碱的效果。在实验1中，10名健康男性志愿者在适应ME刺激之前接受了安慰剂、0.6毫克、1.2毫克或1.8毫克的东莨菪碱，在适应后10至70分钟重复进行的测试中显示出显著的线性剂量依赖性。在实验2中，12名男性志愿者适应了ME刺激，然后接受了安慰剂、1.2毫克口服东莨菪碱或0.75毫克皮下注射毒扁豆碱。在随后的重复测试中，相对于安慰剂，东莨菪碱增强了ME的强度，毒扁豆碱则使其减弱。两个实验均为双盲双模拟重复测量实验。这些数据支持这样一种观点，即ME是视觉系统中抑制机制的产物，而非联想学习所涉及的过程。
