Some experts have warned that bribing children to eat healthy foods can be counter-productive, undermining their intrinsic motivation and actually increasing disliking. Lucy Cookeand colleagues have found no evidence for this in their new large-scale investigation of the issue. They conclude that rewards could be an effective way for parents to improve their children's diet. '...rewarding children for tasting an initially disliked food produced sustained increases in acceptance, with no negative effects on liking,' they said.
Over four hundred four- to six-year-olds tasted six vegetables, rated them for taste and then ranked them in order of liking. Whichever was their fourth-ranked choice became their target vegetable. Twelve times over the next two weeks, most of these children were presented with a small sample of their target vegetable and encouraged to eat it. Some of them were encouraged with the reward of a sticker, others with the reward of verbal praise, while the remainder received no reward (a mere exposure condition). A minority of the children formed a control group and didn't go through an intervention of any kind.
After the two-week period, all the intervention children showed equal increases in their liking of their target vegetable compared with the control children. However, when given the chance to eat as much of it as they wanted (knowing there was no chance of reward), the kids who had previously earned stickers chose to eat more than the kids who'd just been repeatedly exposed to the vegetable without reward.
At one- and three-month follow-up, the intervention children's increased liking of their target vegetable was sustained regardless of the specific condition they'd been in. However, in terms of increased consumption (when given the opportunity to eat their target vegetable, knowing no reward would be forthcoming), only the sticker and verbal praise children showed sustained increases.
So, how come previous studies have claimed that bribery can undermine children's intrinsic motivation, actually leading to increases in disliking of foods? Cooke and her colleagues think this may be because past lab studies have often targeted foods that children already rather liked. Consistent with this explanation, it's notable that past community studies that reported the successful use of rewards targeted unpopular vegetables just as this study did.
An important detail of the current study is that verbal praise was almost as effective as tangible reward. 'Social reward might be particularly valuable in the home,' the researchers said, 'because it may help parents avoid being accused of unfairness in offering incentives to a fussy child but not to the child's siblings.'
參考譯文:
有些專家說,用賄賂的方法誘使小孩吃素,不但沒能讓他們變得喜歡吃,反而降低了他們的內部動機,適得其反。但是Lucy Cooke和她的同事在一個新的有關該問題的大規模調查研究中,并沒有發現支持這個說法的證據。他們的結論是,獎勵能幫助父母使他們孩子的飲食得到改善。他們說,“用獎勵使小孩吃原先不喜歡的食物,實際上能讓他們慢慢喜歡上吃他們,而且并不會對它們的喜好產生負面影響。”
超過四百個四到六歲的小孩參與了研究。品嘗六種蔬菜之后,要求他們評估其味道并按喜好程度排序,選取被他們排在第四位的那種蔬菜作為其“目標蔬菜”。接下來兩周的十二次試驗,大多數孩子面對少量 “目標蔬菜”并被鼓勵食用之。一些孩子以貼紙或口頭獎勵作為食用“目標蔬菜”的獎賞,而剩下的則沒有獎勵(只是給他們暴露在這些蔬菜中)。另外少數沒有接受任何干預的小孩組成對照組。
兩周后,“對照組小孩”和所有那些“受干預小孩 ”同等表現出了對其“目標蔬菜”喜愛程度上的增加。然而,如果讓他們按照自己意愿選擇吃多少(在知道沒有獎賞的情況下),則與那些沒有獎賞只是重復性的暴露在其“目標蔬菜”中的孩子相比,那些早期試驗中曾得到貼紙做獎賞的小孩吃了更多的“目標蔬菜”。
在之后一個月及三個月的跟進中,不管接受哪種條件干預的小孩,都持續保持著對其“目標蔬菜”增加的喜愛。但就食用量來說(在知道沒有獎賞前提下選擇食用),只有得到貼紙和口頭獎勵的小孩表現出持續增長。
為什么之前的研究,聲稱“賄賂”會破壞小孩的內部動機,反而使小孩更加不喜歡吃那些食物呢?Cooke和她的同事認為,可能是因為以前實驗室研究所選用的目標食物,或許本來就是小孩自己所喜歡的。值得注意的是,以前的社區研究所報道過的“使用獎勵方法讓小孩吃原先不喜歡的蔬菜的成功應用”和本研究的結果是一致的。
本研究的一個重要細節是,口頭獎勵和有形獎勵的效力是幾乎相同的。“在家庭情景中,社會性獎勵也許會更加有用,”研究人員說,“這也許是因為,僅獎勵挑三揀四的小孩,會讓其他小孩覺得不公平,而這也可以幫助父母們避免被指責。”
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