Craver-Lemley C, Reeves A
Northeastern University, Boston, MA 02115.
Perception. 1987;16(5):599-614. doi: 10.1068/p160599.
Mental imagery interferes with perception. This, an example of the 'Perky effect', was studied for vernier acuity. Mean accuracy for reporting the offset of vertical line targets declined from 80% to 65% when subjects were requested to imagine vertical lines near fixation. Images of horizontal lines or of a grey mist in the fixation region lowered accuracy to a similar extent. However, accuracy was barely affected when the image was requested 1.5 deg or more from the target. The Perky effect remained strong for at least 4 s after an instruction to 'clear' the image away. The results were not due to imagery-induced changes in fixation, pupil diameter, or accommodation, or (at least primarily) to central attentional or decisional factors. Rather, imagery produces a local, pattern-insensitive, and relatively long-lasting reduction in visual sensitivity. The sensitivity loss may be mimicked by a 0.24 log unit reduction in target energy.
心理意象会干扰感知。这是“珀基效应”的一个例子，针对游标视力进行了研究。当要求受试者想象在注视点附近有垂直线时，报告垂直线目标偏移的平均准确率从80%降至65%。在注视区域想象水平线或灰色薄雾的图像会使准确率降低到类似程度。然而，当要求在距离目标1.5度或更远的地方形成意象时，准确率几乎没有受到影响。在接到“清除”图像的指令后，珀基效应至少持续4秒。这些结果并非由于意象引起的注视、瞳孔直径或调节变化，也不是（至少主要不是）由于中枢注意力或决策因素。相反，意象会导致视觉敏感度出现局部、对图案不敏感且相对持久的降低。目标能量降低0.24对数单位可能会模拟出这种敏感度损失。
