Chameleons can move their eyes in different directions, and most scientists thought that meant that each eye worked independently from the other. Scientists in Israel say they have discovered, however, that chameleons’ eyes are, in fact, highly coordinated.

Many fish and birds have eyes on opposite sides of the head, and they seemingly have at any given moment two different pictures of the world around them. But chameleons’ eyes are slightly bulging so they can focus both eyes on one object or track two different objects with each eye.

The puzzling question was: does one eye know what the other is doing?

Scientists at Haifa University, in Israel, tried to find the answer with the help of a computer screen.

"We found out that each eye has a different role. We have the tracking eye, that will continue tracking the target, and the converging eye that will converge to the tracking eye, and eventually she will choose that target," said Hadas Ketter-Katz, who is a scientist at the university. "We found out that each eye has a different subtle pattern of eye movements according to her role.”

Split screen

When the picture of an insect projected on the screen was split in two, which then started to move in opposite directions, the chameleon was able to follow both.

But when the animal finally decided on one of the targets, its other eye suddenly swiveled back to focus on the same spot. In a split second, it lashed out its long tongue at the target. This proved that the second eye knew what the first eye was seeing.

"We assume that the brain controls each eye independently with independent units of eye movements, but there is a higher level of control that can co-ordinate these two. So each eye knows exactly what the other eye sees and vice versa,” said Ketter-Katz.

Scientists say new findings may shed new light on research on other, similar animals. It also could find application in the control of mechanical devices — such as robots or self-driving cars — whose video cameras have to focus simultaneously on several things.


變色龍的兩眼可以往不同方向轉動。以往大部分科學家認為這表示變色龍的兩眼是獨立運作的，但以色列的科學家發現，變色龍的兩眼間事實上有高度的協調性(highly coordinated)。

許多魚類跟鳥類的雙眼都位於頭部兩 側(on opposite sides)，而這兩隻眼睛似乎無時無刻(at any given moment)看到的都是各自周圍的圖像。但變色龍的雙眼微微凸起(bulge)，所以 能同時聚焦(focus . . . on . . .)在同一物體上，也可以各自追蹤(track)兩個不 同的物體。

但真正令人不解的問題是：其中一隻眼睛會知道另一隻眼睛在做什麼嗎？

以色列海法大學(Haifa University)的科學家透過了電腦螢幕來嘗試找到問題的答案。

海法大學的科學家Hadas Ketter-Katz說明研究發現：「我們發現兩隻眼睛有不同的角色。有一隻眼睛會負責追蹤，一直追蹤某個目標，而另一隻眼則會與負責追蹤的眼睛會合(converge)， 變色龍最後就會選定這個目標。兩隻眼睛因角色不同，運動模式會有微妙的(subtle)差 異。」

分割的畫面

科學家把投射在螢幕上的蟲子影像分 割為二(split in two)，再將兩者往反方向(in opposite directions)移動，此時變色龍會同時追蹤兩個影像。

但是當變色龍選定目標時，一隻眼睛就會快速轉旋回來(swivel back)聚 焦在同一個點上，再以迅雷不及 掩耳的速度(in a split second)對著目標甩射出(lash out)舌 頭，發動攻擊。這證明第二隻眼睛的確知道第一隻眼睛看到的東西。

「我們認為變色龍腦袋使用不同的、各自獨立的單元來控制兩眼各別的眼睛運動，但還有一個更高的控制層級來統合雙眼，所以一隻眼睛會知道另一隻眼睛看到了什 麼，反過來亦是如此(vice versa)。」科學家認為這些新發現可以對其他類似動物的研究帶來新的看法(shed new light on . . .)。也可能在機器裝置上有所運用(application)， 像是須要有攝影機同時 (simultaneously)關注數個物件的機器人或是自動駕駛車。