Avoidance of Certain Foods and Classical Conditioning

A conditioned taste aversion involves the avoidance of a certain food following a period of illness after consuming that food. These aversions are a great example of how classical conditioning can result in changes in behavior, even after only one incidence of feeling ill.

How Do Conditioned Taste Aversions Work?

你有没有吃过东西后生病，后来发现一想到那食物就觉得有点反胃？这是一个很好的例子，通常被称为条件味觉厌恶。

A conditioned taste aversion can occur when eating a substance is followed by illness. For example, if you ate sushi for lunch and then became ill, you might avoid eating sushi in the future, even if it had no relationship to your illness.

虽然我们可能会避免食用紧接着生病的食物，但研究表明，食用这些食物和疾病的发生并不一定要紧密地联系在一起。即使在中性刺激（吃食物）和刺激之间有很长的延迟，条件性的味觉厌恶也会产生无条件刺激（感觉不舒服）。

条件味觉厌恶的例子

Imagine that you are on vacation and eat a chicken enchilada at a restaurant. Hours after eating the enchilada, you become violently ill. For years after that incident, you might be unable to bring yourself to eat a chicken enchilada and may even feel queasy when you smell foods that remind you of that particular dish.

即使你知道你的疾病与吃特定的食物无关，这种条件性的味觉厌恶也会发生。实际上，你可能完全意识到，你是从旅行前几天生病的一个同伴那里感染了一种恶心的胃部病毒。

Consider your own aversions to certain foods. Can you link your distaste for particular items to a period of illness, queasiness, or nausea? People may find that they avoid very specific types of food for years simply because they consumed that particular item before they became ill.

理解味觉厌恶

味觉厌恶能有意识地和有意识地发生吗不知不觉? 在许多情况下，人们可能完全不知道他们不喜欢某种食物的根本原因。为什么会出现这些厌恶味道的现象，尤其是当我们意识到疾病与某种特定的食物无关时？

条件性味觉厌恶是一个很好的例子some of the fundamental mechanics of classical conditioning.

• The previously neutral stimulus (the food) is paired with an unconditioned stimulus (an illness), which leads to anunconditioned response（感觉不舒服）。
• After this one-time pairing, the previously neutral stimulus (the food) is now aconditioned stimulusthat elicits aconditioned response(avoiding the food).

这就是这些条件化的味觉厌恶的全部吗？上面描述的场景并不完全符合经典条件反射的标准期望。

首先，条件反射发生在中性刺激和非条件刺激（UCS）的单一配对之后。其次，中性刺激和UCS之间的时间跨度通常只有几秒钟。在条件味觉厌恶的情况下，时间的推移往往达几个小时。

While it may seem to violate the general principles of classical conditioning, researchers have been able to demonstrate the effects of conditioned taste aversions in experimental settings.

在一个这样的实验中，心理学家John Garcia将调味的水（以前中性刺激）喂给实验室大鼠。几个小时后，将大鼠注射物质（UCS），使其生病。后来，当大鼠提供味道水时，他们拒绝喝它。

Explaining Conditioned Taste Aversions

因为加西亚的研究与之前对经典条件反射的理解相矛盾，许多心理学家对研究结果并不信服。Pavlovhad suggested that任何中性刺激可能引起条件反应。

If that were true, then why would the feelings of sickness be associated with the food that was eaten hours earlier? Wouldn't the illness be associated with something that had happened right before the symptoms occurred?

"Taste aversions do not fit comfortably within the present framework of classical or instrumental conditioning," Garcia noted. "These aversions selectively seek flavors to the exclusion of other stimuli. Interstimulus intervals are a thousand-fold too long."

What Garcia and other researchers were able to demonstrate was that in some cases, the type of neutral stimulus useddoeshave an influence on the conditioning process. So why does the type of stimulus matter so much in this particular case?

One part of the explanation lies in the concept of性准备。基本上，几乎每个生物都在生物学上倾向于在某些刺激之间产生某些关联。

If an animal eats food and then becomes ill, it might be very important to the animal's continued existence to avoid such foods in the future. These associations are frequently essential for survival, so it is no wonder they form easily.

A Word From Verywell

经典条件作用可以对行为产生强大的影响。条件性味觉厌恶清楚地表明，有时学习可以很快发生（仅在一个实例之后）。

下一次当你发现自己不喜欢某一种食物时，考虑一下条件反射的厌恶可能在你不喜欢某一种食物时所起的作用。