如果你在看完電影后走到陽光下,，或是盯住一部照相機(jī)的閃光燈，這時(shí)你的瞳孔將會(huì)收縮,。
日前,，發(fā)表在美國(guó)《國(guó)家科學(xué)院院刊》（PNAS）網(wǎng)絡(luò)版上的一項(xiàng)研究結(jié)果稱，如果你僅僅是觀看一個(gè)明亮物體的圖像,，也會(huì)出現(xiàn)同樣的結(jié)果,，即瞳孔也會(huì)收縮。
研究人員要求志愿者凝視一系列視覺錯(cuò)誤圖像——包括成圓圈向內(nèi)排列的淚珠要比向外排的淚珠,，在中心上看起來更亮一些（如圖所示）,，隨后測(cè)量這些受試者的瞳孔發(fā)生了哪些變化。
挪威奧斯陸大學(xué)的Bruno Laeng和Tor Endestad發(fā)現(xiàn),，物體看起來越亮,，瞳孔收縮得也就越厲害。在最初的收縮之后,，瞳孔會(huì)逐漸放大，以反射到達(dá)眼睛的實(shí)際數(shù)量的光線,。
這一研究與之前的成果結(jié)合在一起,，表明當(dāng)觀看一些吸引我們或讓人感興趣的事物時(shí)，我們的瞳孔會(huì)擴(kuò)張,，這意味著所謂的瞳孔光反射并不僅僅是一種下意識(shí)的反應(yīng)（就像你的手會(huì)從熱火爐上抽走一樣）,。相反，更高級(jí)的大腦功能的輸入——例如負(fù)責(zé)解釋我們所看到的事物——在其中也扮演了一個(gè)重要角色,。（生物谷Bioon.com）
doi:10.1073/pnas.1118298109
PMC:
PMID:
Bright illusions reduce the eye's pupil
Laeng, Bruno; Endestad, Tor
We recorded by use of an infrared eye-tracker the pupil diameters of participants while they observed visual illusions of lightness or brightness. Four original illusions {based on Gaetano Kanisza's [Kanizsa G (1976) Subjective contours. Sci Am 234:48–52] and Akiyoshi Kitaoka's [Kitaoka A. (2005) Trick Eyes (Barnes & Noble, New Providence, NJ).] examples} were manipulated to obtain control conditions in which the perceived illusory luminance was either eliminated or reduced. All stimuli were equiluminant so that constrictions in pupillary size could not be ascribed to changes in light energy. We found that the pupillary diameter rapidly varied according to perceived brightness and lightness strength. Differences in local contrast information could be ruled out as an explanation because, in a second experiment, the observers maintained eye fixation in the center of the display; thus, differential stimulation of the fovea by local contrast changes could not be responsible for the pupillary differences. Hence, the most parsimonious explanation for the present findings is that pupillary responses to ambient light reflect the perceived brightness or lightness of the scene and not simply the amount of physical light energy entering the eye. Thus, the pupillary physiological response reflects the subjective perception of light and supports the idea that the brain's visual circuitry is shaped by visual experience with images and their possible sources.
