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Sociallearning in animals is said to occur whendirect or indirect social interactionfacilitates the acquisition of anovel behavior. It usually takes theform of an experienced animal (thedemonstrator) performing a behavior suchthat the naïve animal (theobserver) subsequently expresses the same behaviorsooner, or morecompletely, than it would have otherwise. One example ofsociallearning is the acquisition of preferences for novel foods.
Some experiments have suggested that among mammals, social learningfacilitatesthe identification of beneficial food items, but that amongbirds, sociallearning helps animals avoid toxic substances. Forexample, one study showedthat when red-wing blackbirds observed othersconsuming a colored food or afood in a distinctly marked container andthen becoming ill, they subsequentlyavoided food associated with thatcolor or container. Another experimentshowed that house sparrowsconsumed less red food after they observed otherseating red food thatwas treated so as to be noxious. Studies on nonavianspecies have notproduced similar results, leading researchers to speculatethat aviansocial learning may be fundamentally different from that of mammals.
But Sherwin’s recent experiments with domestic hens do not supportthe notionthat avian social learning necessarily facilitates aversionto novel foods thatare noxious or toxic. Even when demonstrator hensreacted with obviousdisgust to a specific food, via vigorous headshaking and bill wiping, therewas no evidence that observerssubsequently avoided eating that food. Sherwin’sresearch teamspeculated that ecological or social constraints during theevolution ofthis species might have resulted in there being little benefitfrom thesocial learning of unpalatability, for instance, selective pressuresforthis mode of learning would be reduced if the birds rarelyencounterednoxious or toxic food or rarely interacted after eating suchfood, or if theconsequences of ingestion were minimal. In a relatedexperiment, the sameresearchers showed that if observer hens watcheddemonstrator hens reactfavorably to food of a particular color, thenobserver hens ate more food ofthat color than they ate of food of othercolors. These results confirmed thatavian species can developpreferences for palatable food through sociallearning.
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The primary purpose of the passage is todiscuss the
techniques used incertain experiments on social learning in birds
reasons for thedifferences between social learning in birds and in mammals
question of how sociallearning manifests itself in birds
basis for a widespreadbelief about a difference in behavior between birds and mammals
possible reasons whybirds may or may not learn from each other in a particular way
答案是E 為啥不是 B 拜托分析下其它選項啊！
Manypoliticians, business leaders, and scholarsdiscount the role of publicpolicy and emphasize the role of the labor marketwhen explainingemployers’ maternity-leave policies, arguing that prior to thepassageof the Family and Medical Leave Act (FMLA) of 1993, employerswerealready providing maternity leave in response to the increase inthenumber of women workers. Employers did create maternity-leaveprograms inthe 1970’s and 1980’
s, but not as a purelyvoluntaryresponse in the absence of any government mandate. In 1972,the EqualEmployment Opportunity Commission (EEOC) ruled that employerswho allowedleaves for disabling medical conditions must also allow themfor maternity andthat failure to do so would constitute sexdiscrimination under the CivilRights Act of 1964. As early as 1973, asurvey found that 58 percent oflarge employers had responded with newmaternity-leave policies. Becausethe 1972 EEOC ruling was contested incourt, the ruling won press attentionthat popularized maternity-leavepolicies. Yet perhaps because theSupreme Court later struck down theruling, politicians and scholars have failedto recognize its effects,assuming that employers adopted maternity-leavepolicies in response tothe growing feminization of the workforce.
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Itcan be inferred that the author of thepassage would be most likely toagree with which of the following statementsabout government policy?
Government policy isgenerally unaffected by pressures in the labor market.
The impact of a givengovernment policy is generally weakened by sustained press attention.
It is possible for aparticular government policy to continue to have an impact after that policyhas been eliminated.
A given governmentpolicy can be counterproductive when that policy has already unofficially beenimplemented.
The impact of a givengovernment policy is generally weakened when the ruling is contested in court.
答案是C 我真的沒有看到原文里有eliminate這個字！A為什么不正確？
拜托拜托！！！磕頭了！！！ |
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发表于 2009-11-29 21:25:21
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