GWD-28-5

snowjing

28-passage one

Social learning in animals is said to occur when direct or indirect social interaction facilitates the acquisition of a novel behavior. It usually takes the form of an experienced animal (the demonstrator) performing a behavior such that the naïve animal (the observer) subsequently expresses the same behavior sooner, or more completely, than it would have otherwise. One example of social learning is the acquisition of preferences for novel foods. Some experiments have suggested that among mammals, social learning facilitates the identification of beneficial food items, but that among birds, social learning helps animals avoid toxic substances. For example, one study showed that when red-wing blackbirds observed others consuming a colored food (30) or a food in a distinctly marked container and then becoming ill, they subsequently avoided food associated with that color (35) or container. Another experiment showed that house sparrows consumed less red food after they observed others eating (40) red food that was treated so as to be noxious.  Studies on non-avian species have not produced similar results, leading researchers to speculate that avian social learning may be fundamentally different from that of mammals.

But Sherwin's recent (50) experiments with domestic hens do not support the notion that avian social learning necessarily facilitates aversion to novel (55) foods that are noxious or toxic. Even when demonstrator hens reacted with obvious disgust to a specific food, via vigorous head (60) shaking and bill wiping, there was no evidence that observers subsequently avoided eating that food. Sherwin's research team speculated that ecological or social constraints during the evolution of this species might have resulted in there being little benefit from the social learning of atability, for instance, selective pressures for this mode of learning would be reduced if the birds rarely encountered noxious or toxic food or rarely interacted after eating such food, or if the consequences of ingestion were minimal. (80) In a related experiment the same researchers showed that if observer hens watched demonstrator hens react favorably to food of a particular color, then observer hens ate more food of that color than they ate of food of other colors. These results confirmed that avian species can develop preferences for palatable food through social learning.

28-5: According to the passage, which of the following is true of the experiments on domestic hens conducted by Sherwin’s research team?

A: Only a small number of observer hens appeared to learn to avoid food that was demonstrated by other hens to be noxious.

B: Observer hens ingested food preferentially only after numerous instances of witnessing demonstrator hens preferentially ingest that type of food.

C: Observer hens appeared unable to recognize when demonstrator hens found a particular food especially palatable.

D: Observer hens appeared unable to recognize when demonstrator hens found a particular food especially palatable.

E: Demonstrator hens altered their behavior less obviously in response to noxious foods than in response to highly palatable foods.

为什么这里的答案是E? 问题应该不会错吧, 这题C和D一样? 

[此贴子已经被作者于2005-12-11 6:25:27编辑过]

carolhide

But Sherwin's recent (50) experiments with domestic hens do not support the notion that avian social learning necessarily facilitates aversion to novel (55) foods that are noxious or toxic.

AND

In a related experiment the same researchers showed that if observer hens watched demonstrator hens react favorably to food of a particular color, then observer hens ate more food of that color than they ate of food of other colors.

snowjing

是啊.所以这里似乎强调的是observer的动作或反映.而E完全是从demonstrator角度出发的.

思路错???

uibewsj

    

GWD28-Q3 to Q6:

    

      Social learning in animals

    

       is
said to occur when direct

    

       or
indirect social interaction

    

Line       facilitates the acquisition

    

(5)    of a novel behavior.  It

    

usually takes
the form of

    

an experienced
animal (the

    

demonstrator)
performing a

    

behavior such
that the naive

    

 (10)      animal (the observer) sub-

    

sequently
expresses the

    

same behavior sooner, or

    

more completely,
than it

    

would have
otherwise.  One

    

 (15)      example of social learning

    

is the
acquisition of prefer-

    

ences for novel
foods.

    

      Some experiments

    

have suggested that among

    

 (20)      mammals, social learning

    

       facilitates
the identification

    

       of
beneficial food items,

    

but that among birds, social

    

learning helps animals

    

 (25)      avoid toxic substances.

    

For example, one
study

    

showed that when
red-wing

    

blackbirds
observed others

    

consuming a
colored food

    

 (30)      or a food in a distinctly

    

marked container
and then

    

becoming ill,
they subse-

    

       quently
avoided food

    

associated with
that color

    

 (35)
               or
container.  Another

    

experiment showed that

    

house sparrows consumed

    

less red food
after they

    

      observed others eating

    

 (40)     red
food that was treated

    

so as to be
noxious.有害的  Studies

    

on nonavian非鸟类 species have

    

not produced similar results,

    

leading researchers to

    

 (45)      speculate that avian social

    

learning may be fundamen-

    

tally different from that of

    

mammals.

    

      But Sherwin’s recent

    

 (50)      experiments with domestic

    

hens do not
support the

    

notion that
avian social

    

learning
necessarily facili-

    

tates aversion
to novel

    

 (55)      foods that are noxious or

    

toxic.  Even when demon-

    

strator hens reacted with

    

obvious disgust to a specific

    

food, via
vigorous head

    

 (60)      shaking and bill wiping,

    

there was no evidence that

    

observers subsequently

    

avoided eating that food.

    

Sherwin’s
research team

    

 (65)      speculated that ecological

    

or social
constraints during

    

the evolution of
this species

    

might have
resulted in there

    

being little
benefit from the

    

 (70)      social learning of unpal-

    

atability, for
instance,

    

selective
pressures for this

    

mode of learning
would be

    

reduced if the
birds rarely

    

 (75)      encountered noxious or

    

toxic food or
rarely inter-

    

acted after
eating such food,

    

or if the
consequences of

    

ingestion were
minimal.

    

(80)        
In a related experiment,

    

the same
researchers

    

showed that if observer

    

hens watched demonstrator

    

hens react favorably to food

    

(85)        
of a particular color, then

    

observer hens ate more

    

food of that color than they

    

ate of food of
other colors.

    

These results confirmed that

    

 (90)      avian
species can develop

    

preferences for palatable

    

food through social learning.

我再贴一遍原文...请问为何选Q5-E.： Demonstrator hens altered their behavior less obviously in
     response to noxious foods than in response to highly palatable foods.

那里可看出Demonstrator hens吃了美味的食物比吃了有害的食物做出的反应更大？下面这段不是正说明demonstrator吃了有害的食物后反应很大么？

    

 (55)      foods that are noxious or

    

toxic.  Even when demon-

    

strator hens reacted with

    

obvious disgust to a specific

    

food, via
vigorous head

    

 (60)      shaking and bill wiping,

    

there was no evidence that

    

observers subsequently

    avoided eating that
food.

而根据文中对demonstrator吃了美味食物后的描述，没看出反应有多大啊：

    

(80)        
In a related experiment,

    

the same
researchers

    

showed that if observer

    

hens watched demonstrator

    

hens react favorably to food

    

(85)        
of a particular color, then

    

observer hens ate more

    

food of that color than they

    

ate of food of
other colors.

并且，假如E对，那不是表明Observer只有在Demonstrator吃了美味食物，作出极大反应后才有social learning，那不是又引向另一个话题了么？

michaellu97

vote D

寒露

D. Demonstrator hens reacted adversely to ingesting certain novel foods.

E. Demonstrator hens altered their behavior less obviously in response to noxious foods than in response to highly palatable foods.

我也选D，和56-58行说的意思吻合。Demonstrator hens 对noxious foods 和 highly palatable foods.的都有反映，没说哪个反映更obviously ，只是observers的反映不同而已。所以E 不对。

remondxz

答案错了，肯定是D, 支持LZ

wingkim

D. Demonstrator hens reacted adversely to ingesting certain novel foods.

显然原文没有说明怎样才是正常的反应，自然也没有相反的反应；况且常理家鸡吃了不好的东西却实是猛甩头和磨嘴的，这个就是正常的反应。

我原来选的A：Only a small number of observer hens appeared to learn to avoid food that was demonstrated by other hens to be noxious.

但是small number是否可以表达一个几乎没有的情况就不确定了，因为原文描述：

Sherwin’s research team

 (65)      speculated that ecological

or social constraints during

the evolution of this species

might have resulted in there

being little benefit from the

 (70)      social learning of unpal-

atability,

Aquafer

我窃以为这题没一个答案对。。。

E中把Demonstrator改成observer还差不多

cyyp

害人不浅的题目阿，害得我怎么也做不出来,anyway，e中说Demonstrator hens altered their behavior less obviously是怎么也不对的，明明文章写得清楚“when a demonstrator hens reacted with obvious disgust”的嘛！

不管，这道题目不算！