Department of Psychology, Oxford Brookes University, UK.
Int J Neurosci. 2011 Mar;121(3):159-64. doi: 10.3109/00207454.2010.539308. Epub 2010 Dec 8.
The occurrences of visual hallucinations seem to be more prevalent in low light and hallucinators tend to be more prone to false positive type errors in memory tasks. Here we investigated whether the richness of stimuli does indeed affect recognition differently in hallucinating and nonhallucinating participants, and if so whether this difference extends to identifying spatial context. We compared 36 Parkinson's disease (PD) patients with visual hallucinations, 32 Parkinson's patients without hallucinations, and 36 age-matched controls, on a visual memory task where color and black and white pictures were presented at different locations. Participants had to recognize the pictures among distracters along with the location of the stimulus. Findings revealed clear differences in performance between the groups. Both PD groups had impaired recognition compared to the controls, but those with hallucinations were significantly more impaired on black and white than on color stimuli. In addition, the group with hallucinations was significantly impaired compared to the other two groups on spatial memory. We suggest that not only do PD patients have poorer recognition of pictorial stimuli than controls, those who present with visual hallucinations appear to be more heavily reliant on bottom up sensory input and impaired on spatial ability.
幻觉的发生似乎在低光环境下更为普遍，而幻觉患者在记忆任务中更容易出现假阳性错误。在这里，我们研究了刺激的丰富程度是否确实会对幻觉和非幻觉参与者的识别产生不同的影响，如果是这样，这种差异是否会扩展到识别空间背景。我们比较了 36 名患有视觉幻觉的帕金森病 (PD) 患者、32 名无幻觉的帕金森病患者和 36 名年龄匹配的对照组，他们在一项视觉记忆任务中接受了不同位置呈现的彩色和黑白图片的测试。参与者必须在干扰物中识别出图片以及刺激的位置。研究结果显示出组间的明显差异。两组 PD 患者的识别能力均较对照组差，但有幻觉的患者对黑白图片的识别能力明显比彩色图片差。此外，有幻觉的组在空间记忆方面明显比其他两组受损。我们认为，不仅 PD 患者对图像刺激的识别能力比对照组差，而且出现视觉幻觉的患者似乎更依赖于自上而下的感官输入，空间能力受损。
