后像

后像（Afterimage）是在眼睛接触原始影像一段时间后，继续出现在眼睛中的影像。后像可能是正常现象（生理性后像），也可能由疾病引起（持续性后像（英语：Palinopsia））。幻视持续性后像（英语：Illusory palinopsia）（Illusory palinopsia）可能是生理后像的病态夸大。后像的成因是视网膜在眼睛未受原始刺激时却仍维持光化学活动。^[1]^[2]

有种常见的生理性后像是发生在短暂注视光源（例如相机闪光灯）后，这种后像看起来像是有个暗淡面积漂浮在眼前。持续性后像（Palinopsia）是视雪症的常见症状。

负后像

负性（英语：Negative (photography)）的后像主要是由视网膜神经节细胞（英语：Retinal ganglion cell）的神经性适应造成，视网膜神经节细胞会将讯号从眼睛的视网膜传到大脑其他部分。^[3]当眼睛的感光细胞（视杆细胞和视锥细胞）适应过度刺激并失去敏感性时也会轻微引起负性后像。^[4]另外大脑也有所影响。^[5]

杨-亥姆霍兹三原色理论（英语：Young–Helmholtz theory）假设眼睛中存在三种感光细胞，每种感光细胞只对特定范围的可见光敏感：短波长视锥细胞、中波长视锥细胞、长波长视锥细胞。然而，三原色理论并不能解释所有的后像现象。明确来说，后像是适应性刺激的互补色调，而三原色理论无法解释这一事实。^[6]

三原色理论无法解释后像，这表示需要一种对立历程理论（英语：Opponent process），如Ewald Hering（1878）阐述并由 Hurvich和 Jameson（1957）进一步发展的理论。^[7]对立历程理论指出，人类视觉系统以对抗性的方式处理来自视锥细胞和视杆细胞的讯号，由此解释颜色资讯。对立色理论是指存在三个对立频道：红对绿、蓝对黄、黑对白。对某一种对立通道的其中一种颜色的响应与对另一种颜色的响应有拮抗作用。因此可解释为何绿色影像会产生洋红色后像，这是因为绿色使绿色频道产生适应性，因此会产生减弱过的讯号，任何导致绿色减少的东西都被解释为其原色的配对，也就是洋红色（红色和蓝色的等量混合）。^[7]

在观看示例影片并移开视线后，会产生扭曲的错觉。参见运动后效。

正后像

相比之下，正后像的颜色看起来与原始影像相同，大多极为短暂，只持续不到半秒。正后像成因尚不清楚，但可能反映了大脑的持续性活动，此时视网膜感光细胞会持续向枕叶发送神经冲动。^[8]

产生正像的刺激通常会在适应过程中迅速触发负后像，要体验这种现象，可以先看向明亮的光源，再把目光移至暗处，比如闭上眼睛。一开始应该会看到渐渐消失的正后像，随后可能会出现持续时间更长的负后像。也有可能看到任意不明亮物体的后像，只是这些后像只会持续片刻，大多数人不会注意到。^{[来源请求]}

图库

美国国旗的相反色
白色方块
意大利国旗的相反色

参见

注记

^ Bender, MB; Feldman, M; Sobin, AJ. Palinopsia.. Brain: A Journal of Neurology. Jun 1968, 91 (2): 321–38. PMID 5721933. doi:10.1093/brain/91.2.321.
^ Gersztenkorn, D; Lee, AG. Palinopsia revamped: A systematic review of the literature.. Survey of Ophthalmology. Jul 2, 2014, 60 (1): 1–35. PMID 25113609. doi:10.1016/j.survophthal.2014.06.003.
^ Zaidi, Q., Ennis, R., Cao, D., & Lee, B. Neural locus of color afterimages. .. Current Biology. 2012, 22 (3): 220–224 [17 October 2022]. （原始内容存档于2024-06-10）.
^ Williams, D. R., & MacLeod, D. I. A. Interchangeable backgrounds for cone afterimages.. Vision Research. 1979, (8): 867–877 [17 October 2022].
^ Shimojo, S; Kamitani, Y; Nishida, S. Afterimage of perceptually filled-in surface. Science. 2001, 293 (5535): 1677–80. Bibcode:2001Sci...293.1677S. PMID 11533495. S2CID 41840423. doi:10.1126/science.1060161.
^ Horner, David. T. Demonstrations of Color Perception and the Importance of Colors. Ware, Mark E.; Johnson, David E. (编). Handbook of Demonstrations and Activities in the Teaching of Psychology. II: Physiological-Comparative, Perception, Learning, Cognitive, and Developmental. Psychology Press. 2013: 94–96 [2019-12-06]. ISBN 978-1-134-99757-2. Originally published as: Horner, David T. Demonstrations of Color Perception and the Importance of Contours. Teaching of Psychology. 1997, 24 (4): 267–268. ISSN 0098-6283. S2CID 145364769. doi:10.1207/s15328023top2404_10.
^ ^7.0 ^7.1 Horner, David. T. Ware, Mark E.; Johnson, David E. , 编. Handbook of Demonstrations and Activities in the Teaching of Psychology. II: Physiological-Comparative, Perception, Learning, Cognitive, and Developmental. Psychology Press. 2013: 94–96 [2019-12-06]. ISBN 978-1-134-99757-2. Originally published as: Horner, David T. Demonstrations of Color Perception and the Importance of Contours. Teaching of Psychology. 1997, 24 (4): 267–268. ISSN 0098-6283. S2CID 145364769. doi:10.1207/s15328023top2404_10.
^ positiveafterimage. www.exo.net. [2023-02-07]. （原始内容存档于2017-04-22）.

[1] Bender, MB; Feldman, M; Sobin, AJ. Palinopsia.. Brain: A Journal of Neurology. Jun 1968, 91 (2): 321–38. PMID 5721933. doi:10.1093/brain/91.2.321.

[2] Gersztenkorn, D; Lee, AG. Palinopsia revamped: A systematic review of the literature.. Survey of Ophthalmology. Jul 2, 2014, 60 (1): 1–35. PMID 25113609. doi:10.1016/j.survophthal.2014.06.003.

[3] Zaidi, Q., Ennis, R., Cao, D., & Lee, B. Neural locus of color afterimages. .. Current Biology. 2012, 22 (3): 220–224 [17 October 2022]. （原始内容存档于2024-06-10）.

[Williams&1979-4] Williams, D. R., & MacLeod, D. I. A. Interchangeable backgrounds for cone afterimages.. Vision Research. 1979, (8): 867–877 [17 October 2022].

[Shimojo-5] Shimojo, S; Kamitani, Y; Nishida, S. Afterimage of perceptually filled-in surface. Science. 2001, 293 (5535): 1677–80. Bibcode:2001Sci...293.1677S. PMID 11533495. S2CID 41840423. doi:10.1126/science.1060161.

[Horner2-6] Horner, David. T. Demonstrations of Color Perception and the Importance of Colors. Ware, Mark E.; Johnson, David E. (编). Handbook of Demonstrations and Activities in the Teaching of Psychology. II: Physiological-Comparative, Perception, Learning, Cognitive, and Developmental. Psychology Press. 2013: 94–96 [2019-12-06]. ISBN 978-1-134-99757-2. Originally published as: Horner, David T. Demonstrations of Color Perception and the Importance of Contours. Teaching of Psychology. 1997, 24 (4): 267–268. ISSN 0098-6283. S2CID 145364769. doi:10.1207/s15328023top2404_10.

[Horner-7] 7.0 ^7.1 Horner, David. T. Ware, Mark E.; Johnson, David E. , 编. Handbook of Demonstrations and Activities in the Teaching of Psychology. II: Physiological-Comparative, Perception, Learning, Cognitive, and Developmental. Psychology Press. 2013: 94–96 [2019-12-06]. ISBN 978-1-134-99757-2. Originally published as: Horner, David T. Demonstrations of Color Perception and the Importance of Contours. Teaching of Psychology. 1997, 24 (4): 267–268. ISSN 0098-6283. S2CID 145364769. doi:10.1207/s15328023top2404_10.

[8] sitiveafterimage. www.exo.net. [2023-02-07]. （原始内容存档于2017-04-22）.

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