小孩不愛吃蔬菜 是天生的
摘錄自：天下雜誌 經濟學人電子報 2013/11/22
2013-11-21 Web only 作者：經濟學人
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| 圖片來源：陳德信 |
蜘蛛和蛇可能十分危險，所以人天生就害怕牠們並不令人意外。但害怕植物？聽起來很怪，但害怕植物在演化上或許十分合理──至少在年紀小、不知何者有用何者有害之時是如此。
修剪過的草坪、裝飾用的樹林和樹叢、密集種植的水果和蔬菜，都是現代人類的植物王國體驗，但人類祖先碰到的可不是這樣。許多植物含有毒性、帶有毒鬚或長滿尖刺，也可能三者皆有。耶魯大學伍爾茲（Annie Wertz）和維恩（Karen Wynn）的初期研究顯示，嬰孩就算不是害怕植物，至少也對植物懷有警惕之心。
伍爾茲和維恩博士找來一群8至18個月大的嬰兒，將6個物件放到他們眼前：真的歐芹植物、真的羅勒植物、擬真的假歐芹植物、擬真的假羅勒植物，以及兩個怪異的人造品。第一個人造品是以兩個藍色的紙筒製成，上頭漆著黃條紋，還飾有類似假羅勒的織造葉，但染成黑色且向下垂吊。第二個的顏色與塑膠歐芹相同，只不過是以煙斗通條和珠子製成。
各個物件以隨機次序展示於孩童（他們都坐在家長的大腿上）眼前，並拍攝他們的反應。伍爾茲和維恩博士分析結果後，發現「志願者」對假植物和真植物的反應時間相同，平均要等9.9秒才會伸手摸它們。相反地，他們平均只等4.4秒就會伸手觸摸奇怪的人造物。
這表示孩童對植物和新奇人造物的反應時間不同，但無法確知那是因為植物令人反感，還是因為新奇的人造物很吸引人。為了檢視這一點，研究者進行了第二項實驗，這次使用貝殼（非植物自然物件）、湯匙（孩童經常觸碰的熟悉物件）、檯燈（孩童不常觸碰的熟悉物件），以及第一次實驗中的兩個新奇人造物。
孩童對這些物件的反應都非常快（貝殼平均3.4秒，湯匙和檯燈為4.6秒，新奇人造物則為6.4秒）。植物確實是例外──不管它們是真是假。
部分生物學家推測，不愛吃蔬菜這種著名的孩童挑食習慣，在一個許多植物帶有毒性的世界之中，其實是個相當合理的反應。本次研究顯示這個假說可能是對的；世界各地的家長想必十分挫折，因為小孩真的是天生就討厭植物。（黃維德譯）
©The Economist Newspaper Limited 2013
The Economist
Evolutionary psychology
Thyme to touch
By The Economist
From The Economist
Published: November 21, 2013
Nov 16th 2013 |From the print edition
Children seem to be born with an innate distrust of plants.
SPIDERS and snakes can be dangerous, so it is not surprising that
people are wary of them from birth. But plants? Odd as it may seem, to be
afraid of plants—at least when young and ignorant about which are useful and
which harmful—might make good evolutionary sense.
The manicured lawns, ornamental trees and bushes, and intensively bred
fruit and vegetables which are modern humans' experience of the plant kingdom
are hardly typical of what their ancestors would have encountered in the
evolutionary past. Many of these would have been packed with poisons, covered
with toxic hairs, furnished with sharp spines or thorns, or possibly all three.
A preliminary study, published in Cognition by Annie Wertz and Karen Wynn at
Yale University, suggests infant children are indeed, if not exactly afraid of
plants, then certainly wary of them.
Dr Wertz and Dr Wynn began by showing a group of children aged between
eight and 18 months six objects: a real parsley plant, a real basil plant, a
realistic but fake parsley plant, a realistic but fake basil plant, and two
strange artefacts. The first artefact was made from two blue cardboard
cylinders painted with a yellow stripe and decorated with fabric leaves like
those of the fake basil, but dyed black and arranged to hang downwards. The
second was the same colour as the plastic parsley, but made of pipe-cleaners
and beads.
The children (who were sitting on a parent's lap at the time) were
shown the objects in random order, and their reactions filmed. When Dr Wertz
and Dr Wynn had the results analysed, they found that their
"volunteers" responded identically to the fake plants and the real
ones, taking an average of 9.9 seconds before reaching out to touch them. That
contrasted with 4.4 seconds to reach out and touch one of the strange
artefacts.
This showed reactions to plants and novel artefacts are different, but
not whether it is plants that are repellent or novelty that is attractive. To
check that, the researchers did a second experiment, this time using sea shells
(non-plant natural objects), spoons (familiar objects children touch
frequently) and lamps (familiar objects children do not touch frequently) and
also the two novel creations from the first experiment.
The children reacted rapidly to all of these (an average of 3.4 seconds
for the shells, 4.6 seconds for the spoons and lamps, and 6.4 seconds for the
novel artefacts). Plants—whether they are real or artificial—really are
outliers.
Some biologists speculate that children's famously finicky attitude to
eating up their greens is actually a sensible reaction to a world where lots of
plants are toxic. This study suggests this hypothesis might be right, and that,
to the frustration of parents everywhere, phytophobia is indeed a child's
natural lot.
©The Economist Newspaper Limited 2013
