植物開花與光照時間的關(guān)系

地球的公轉(zhuǎn)與自轉(zhuǎn)，帶來了地球上日照長短的周期性變化。由于分布在地球各地的動植物長期生活在具有一定晝夜變化格局的環(huán)境中，借助于自然選擇和進(jìn)化，而形成了各類生物所特有的對日照長度變化的反應(yīng)方式，這就是在生物中普遍存在的光周期現(xiàn)象。例如植物在一定光照條件下的開花、落葉和休眠以及動物的遷移、生殖、冬眠、筑巢和換毛換羽等。

植物的開花有時與日照時間有很大關(guān)系，根據(jù)這個特點，一般將植物分為長日照植物、短日照植物和日中性植物三類。長日照植物，一般是指每天光照時間在14個小時以上才能開花的植物，否則便只進(jìn)行營養(yǎng)生長，不能形成花芽。而且光照時間越長，開花越早。典型的長日照植物有包括：鳳仙花、石榴、茉莉等，作物中有冬小麥、大麥、油菜、菠菜等。它們的花期通常在每年的5-10月。短日照，一般是指每天光照時間在8小時以內(nèi)，通常是深秋、冬季和早春日照的時間。典型的短日照植物有：長壽、秋菊、秋播的葉菜類，如白菜、油菜、生菜等，早春開花的一些木本，如桃樹、杏樹、紫荊、丁香等。它們的花期多在秋、冬、春三季。

日中性植物，它們的開花與日照時間長度沒有任何聯(lián)系，可以說有常年開花的特性。常見的植物有：黃瓜、蒲公英辣椒、矮牛、太陽花等。它們的通常具有邊生長邊開花的習(xí)性，如辣椒，進(jìn)入秋季，枝頭上仍有不少花蕾。光周期對植物的地理分布有較大影響。短日照植物大多數(shù)原產(chǎn)地是日照時間短的熱帶、亞熱帶；長日照植物大多數(shù)原產(chǎn)于溫帶和寒帶，在生長發(fā)育旺盛的夏季，一晝夜中光照時間長。如果把長日照植物栽培在熱帶，由于光照不足，就不會開花。同樣，短日照植物栽培在溫帶和寒帶也會因光照時間過長而不開花。

【英文題源】

Short-dayandlong-dayplant

Tounderstandplantflowering,weneedtogetahandleon"photoperiodism,"oramountoflightanddarknessaplantisexposedto.Theamountofuninterrupteddarknessiswhatdeterminestheformationofflowersonmosttypesofplants,explainedAnnMarieVanDerZanden,horticulturistwiththeOregonStateUniversityExtensionService.

Botanistsusedtothinkthatthelengthofdaylightaplantwasexposedtodeterminewhetheraplantwouldformflowers.Butexperimentsprovedotherwise.Itisthelengthofdarknessthataplantexperiencesthatplaysthemostcrucialrole.

Aplantthatrequiresalongperiodofdarkness,istermeda"shortday"(longnight)plant.Short-dayplantsformflowersonlywhendaylengthislessthanabout12hours.Manyspringandfallfloweringplantsareshortdayplants,includingchrysanthemums,poinsettiasandChristmascactus.Iftheseareexposedtomorethan12hoursoflightperday,bloomformationdoesnotoccur.Otherplantsrequireonlyashortnighttoflower.Thesearetermed"longday"plants.Thesebloomonlywhentheyreceivemorethan12hoursoflight.Manyofoursummerbloomingflowersandgardenvegetablesarelongdayplants,suchasasters,coneflowers,Californiapoppies,lettuce,spinachandpotatoes.Theseallbloomwhenthedaysarelong,duringourtemperatesummers.

Andsomeplantsformflowersregardlessofdaylength.Botanistscallthese"dayneutral"plants.Tomatoes,corn,cucumbersandsomestrawberriesareday-neutral.Someplants,suchaspetuniasdefycategorization,saidVanDerZanden."Theyflowerregardlessofdaylength,butflowerearlierandmoreprofuselywithlongdays,"shesaid.

Horticulturistsandhomegardenersmanipulatethedayandnightlength(indoorswithlights)togetplantstobloomattimesotherthantheywouldnaturally.Forexample,chrysanthemums,shortdayplants,naturallysetflowerandbloomwiththelongnightsofspringorfall.Butbymakingthedaysshorterbycoveringthechrysanthemumsforatleast12hoursadayforseveralweeksoverthelatespringandearlysummer,youcansimulatethelightanddarknesspatternofspringorfall,therebystimulatingsummerblooming.

Oryoucanbringalong-dayplantintobudformationandeventualbloomearlybeforeourdaylengthssurpass12hours,forexample,byputtingtheplantundergrowlightsforafewhoursadaybeyondnaturaldaylengthforafewweeks.Addingsupplementaldaylengthtostimulateearlybloomingisamonpracticeinthenurseryandfreshflowerindustry,especiallythistimeofyear,forValentine'sDayandEasterflowers.

【托福高頻詞】

handle

exposed

uninterrupted

crucial

termed

regardlessof

neutral

manipulate

simulate

blooming

surpass

supplemental

【長難句分析】

Butbymakingthedaysshorterbycoveringthechrysanthemumsforatleast12hoursadayforseveralweeksoverthelatespringandearlysummer,youcansimulatethelightanddarknesspatternofspringorfall,therebystimulatingsummerblooming.

【機經(jīng)簡述及學(xué)科知識】

印加古國的書寫系統(tǒng)

據(jù)考古發(fā)掘，印加帝國有青銅器皿和刀、鐮、斧等勞動工具，其冶煉鑄造技術(shù)相當(dāng)精巧。印加人也有發(fā)達(dá)的農(nóng)業(yè)灌溉系統(tǒng)，綿延的驛道等。印加人的建筑技術(shù)、醫(yī)學(xué)、織布和染色技巧也相當(dāng)發(fā)達(dá)。印加人有自己的語言，可是卻沒有一套書寫文字的系統(tǒng)。印加人利用繩結(jié)記錄法來代替文字，這就是所謂的“奇普”。一直以來，科學(xué)家們就對這些繩結(jié)困惑不已——大多數(shù)文明早期都使用象形文字或圖像，然而印加人留下的卻是棉線和繩結(jié)。難道印加帝國沒有任何形式的書寫方式？若是這樣，那國家大量的數(shù)據(jù)信息將如何保存和傳遞？

大部分科學(xué)家拒絕承認(rèn)“奇譜”是一種書面文件，而認(rèn)為這些繩子是一種保存記憶的設(shè)備，即一種個人化的記憶輔助工具，頂多是一種紡織品算盤，而沒有任何統(tǒng)一的含義。然而，隨著研究的深入，一些研究學(xué)者越來越懷疑這個結(jié)論的正確性。

哈佛大學(xué)考古學(xué)家格里·烏爾頓及其同事通過電腦對這些繩索的各種元素進(jìn)行長期的分析和研究，結(jié)果發(fā)現(xiàn)，奇譜代表的數(shù)字記錄方式，并成功破譯了第一個印加文字—印加的宮殿所在地：普魯楚柯城。

奇譜是一種與眾不同的三維立體的書寫體系，記載著5500公里帝國的信息。科學(xué)家為每一塊“奇譜”都創(chuàng)建了相應(yīng)的數(shù)據(jù)庫，詳細(xì)記錄了它們的各種情況：繩索的大孝長度與顏色，垂掛的穗的數(shù)量，繩結(jié)數(shù)目，每股繩的旋轉(zhuǎn)方向與次數(shù)、年代等，第一次系統(tǒng)地對奇譜進(jìn)行分解與分析。他希望通過數(shù)據(jù)分析找到某些規(guī)律。

這一發(fā)現(xiàn)有助于理解那些繩子中所蘊含的文字信息。例如在陵墓中發(fā)現(xiàn)的奇譜還用作日歷。印加統(tǒng)治者憑借廣大的道路系統(tǒng)和政府體制就可以將食物、人力和原料從安第斯山脈的首都庫斯本運送到其他眾多下級城市。對奇譜的深入分析將有助于揭開其生活細(xì)節(jié)，他們希望根據(jù)奇譜能告訴科學(xué)家這是否是駱駝、勞工或其他貢品。但遺憾的是，目前還沒有其他更令人信服的證據(jù)去證明“奇譜”的文字功能。

【英文題源】

In1532,theSpanishexplorerFranciscoPizarro"discovered"theIncaEmpire,knowntoitsinhabitantsasTawantinsuyu.TheTawantinsuyuEmpirestretchedatotallengthof2485miles,essentiallythelengthoftheSouthAmericancontinentbetweentheAncasmayoRiverattheborderofmoderndayColombiaandEcuador,allthewaytoSantiago,Chile.

Tawantinsuyuwasdividedintofourprovinces,eachwithitsowngovernor.Kingsheldtheirpositionbydivineright;ancestorworshipwasveryelaborateindeed.Theeconomicbaseoftheempirewasmaizeandllamas;anextensivetradeworkwasinplace,withstateartisansworkingingold,textiles,andpolychromeceramics,forselectivedistribution.Themassiveempirewasconnectedbyaplexseriesofroads,over18,000milesofroadsinfact,supportedbyasmanyas2000waystations.ThemonumentalandmunalarchitectureoftheIncaincludessomeofthemostbeautifulandtechnicallyamazingstructuresonthepl,suchasOllantaytambo,andthefamouscityofthecloudsMachuPicchu.Irrigationcanals,suspensionbridges,pavedandbuttressedroads,andspectacularterracesareallcharacteristicsoftheIncaarchitecturalstyle.TheIncaEmpirewassubstantial,sophisticated,andsuccessful.

Butitdidnothavewhatmostoftherestoftheworldwouldrecognizeasawritingsystem.Nocarvedstone,nopapyrus,nowedgespressedintoclay,nolinespaintedonpotsherds.Nothinglikethat.

Ifyouthinkaboutit,aworkingempirewithoutawritingsystemwouldtrulybeanamazingfeat.Empiresrequireaccountants.Whoowestaxes,whoisnextinlineforthethrone,wherearethebestagriculturalfieldsandhowmuchdotheyproduce?Howmanypeopleliveineachsegmentofthesociety?Whatistheweatherlikeinonesectionandhowdoweprotectthepeoplefromdroughtorfamine?Whenshouldweexpectthewinter?Whenisagoodtimetoplant?Howdowekeepallthosepeople,spreadoutsofaralongtheAndes,inlineandinmunicationwiththecenters?Furthermore,whataboutoriginmyths?Whataboutthethousandsofstoriesthataregeneratedbypeoplethatformtheirreligion,theirsociety,theirculturalmemories?Forasocietytofunction,thisinformationmustbekeptsomewhere.

Andsureenough,therewas,infact,awritingsystemamongtheInca;butonesostrangethatitisgoingtotakemealloftheremainingwordsofthisarticletoconvinceyouofthefacts.TheIncakepttheiraccounts,theirgenealogy,theirastronomicalcalculations,and(probably)theirstoriesonaplicatedsystemofcordsandknots,calledquipu(alsospelledkhipu).

WeknowthisinpartbecauseoncetheJesuitmissionariesoftheSpanishInquisitionrecognizedtherangeoffunctionofthequipu,theydidtheirbesttodestroyasmanyashumanlypossible.Thedescriptionofthequipuas"asystemofcordsandknots"doesnotdojusticetotheirplexity;anditisthatplexitythatissoconvincing.Quipushaveinformationstoredinthemusingcordcolor,cordlength,knottype,knotlocation,cordtwistdirection.Cordsareoftenplaitedinbinedcolors;cordssometimeshavesinglethreadsofdistinctivelycottonorwoolwovenin.Cordsareconnectedmostlyfromasinglehorizontalstrand;butsubsidiarycordseofftheverticalstrandsinobliquedirections.

ThereareonlyafewhundredIncaperiodkhipuleft,andintheinterveningcenturies,muchoftheabilitytodecipherthemeaningoftheknotsandcolorshasdisappeared.ArecentcollectionofarticlesinanewbookcalledNarrativeThreads,editedbyJeffreyQuilterandGaryUrton,describeshowahandfulofscholarsareworkingtowardscrackingthecode.Mostexciting,recentexcavationsatthenewlydiscoveredancientcivilizationofCaralhaveidentifiedtheoldestknownquipu,datedto4600yearsago.

【托福高頻詞】

stretched

elaborate

sophisticated

substantial

function

convince

plaited

dyed

intervening

decipher

cracking

【長難句分析】

TheTawantinsuyuEmpirestretchedatotallengthof2485miles,essentiallythelengthoftheSouthAmericancontinentbetweentheAncasmayoRiverattheborderofmoderndayColombiaandEcuador,allthewaytoSantiago,Chile.

Themassiveempirewasconnectedbyaplexseriesofroads,over18,000milesofroadsinfact,supportedbyasmanyas2000waystations.

ThereareonlyafewhundredIncaperiodkhipuleft,andintheinterveningcenturies,muchoftheabilitytodecipherthemeaningoftheknotsandcolorshasdisappeared.

【機經(jīng)簡述及學(xué)科知識】

英國農(nóng)業(yè)的發(fā)展：

17世紀(jì)至19世紀(jì)英國農(nóng)業(yè)生產(chǎn)方式發(fā)生巨大變革的過程。包括圈地運動、機械化、四輪作、良種培育等，其結(jié)果是農(nóng)業(yè)生產(chǎn)效率大大提高。

在這段時期里，歐洲出現(xiàn)了圈地運動（enclosuremovement）。英國的圈地運動最為典型，規(guī)模也最大。15世紀(jì)后，英國毛紡制呢業(yè)迅猛發(fā)展，市場上的羊毛價格開始猛漲，使養(yǎng)羊變得有利可圖，但需要大片的土地。于是，貴族們把原來租種他們土地的農(nóng)民趕走，把可以養(yǎng)羊的土地圈占起來發(fā)展養(yǎng)羊業(yè)。

新航路開辟的影響。新航路開辟后，擴大了世界各地區(qū)、各民族之間的經(jīng)濟(jì)和文化交往。英國地處大西洋航運的中心線上，對外貿(mào)易急劇擴大，從而進(jìn)一步刺激了英國羊毛出口業(yè)和毛織業(yè)的發(fā)展，推動了養(yǎng)羊業(yè)的發(fā)展。利潤的刺激。英國的封建的習(xí)慣地租與資本主義地租之間的差別極大，使地主看到把土地租給農(nóng)業(yè)資本家比對農(nóng)民進(jìn)行封建剝削更為有利可圖，從而刺激了圈地運動的發(fā)展。

18世紀(jì)末，英國的農(nóng)業(yè)已經(jīng)在歐洲居領(lǐng)先地位。在輕視農(nóng)業(yè)的政策的誘導(dǎo)下，農(nóng)業(yè)逐步衰退，英國在食品供應(yīng)方面嚴(yán)重依賴世界市常二戰(zhàn)期間，由于德國潛艇擊毀英國遠(yuǎn)洋商船，糧食進(jìn)口運輸受阻，使國內(nèi)糧食供應(yīng)發(fā)生困難。英國政府不得不實行食品配給制，轉(zhuǎn)而加強對農(nóng)業(yè)的干預(yù)，采取重視農(nóng)業(yè)的許多措施，如：獎勵墾荒、對開墾荒地的農(nóng)戶發(fā)給獎金；擴大耕地面積；提高農(nóng)業(yè)機械化水平；大幅度提高農(nóng)產(chǎn)品價格；各地區(qū)普遍建立農(nóng)業(yè)生產(chǎn)管理委員會，對農(nóng)業(yè)生產(chǎn)進(jìn)行監(jiān)督。戰(zhàn)后，英國花了近15年的時間，扭轉(zhuǎn)了農(nóng)業(yè)衰退的局面，逐步實現(xiàn)了農(nóng)業(yè)現(xiàn)代化。

注：十八世紀(jì)初，英國農(nóng)民采用效率更高的耕種方法，改三田制為圈地，休耕為輪流耕種。

舊方法：三田制新方法：圈地

舊方法：休耕新方法：輪流耕種

【英文題源】

TheDevelopmentofBritishAgriculture

InEnglishsocialandeconomichistory,enclosureistheprocesswhichendstraditionalrightssuchasmowingmeadowsforhay,orgrazinglivestockonmonlandformerlyheldintheopenfieldsystem.Onceenclosed,theseusesofthelandberestrictedtotheowner,anditceasestobemonland.Underenclosure,suchlandisfencedandorentitledtooneormoreowners.TheprocessofenclosurebegantobeawidespreadfeatureoftheEnglishagriculturallandscapeduringthe16thcentury.Bythe19thcentury,unenclosedmonshadbelargelyrestrictedtoroughpastureinmountainousareasandtorelativelysmallpartsofthelowlands.

Theprocessofenclosurehassometimesbeenapaniedbyforce,resistance,andbloodshed,andremainsamongthemostcontroversialareasofagriculturalandeconomichistoryinEngland.ThiscreatedalandlessworkingclassthatprovidedthelaborrequiredinthenewindustriesdevelopinginthenorthofEngland.

LargerfarmersandlandownersinitiallybenefitedfromthegreatlandsalesthatfollowedtheDissolutionoftheMonasteriesinthe1530s,whilemostfarmersgainedfromrisingpricesandfavorableleases.Agriculturalproductivity–particularlyofgrain–wasspurredbyadoublingofpopulationfrombetween2.5and3milliontoover5millionby1660,andanassociatedriseingrainprices.After1650,afallingrainprices,ariseincattlepricesanddemandfromLondonandothergrowingurbanmarkets,ledtoariseincattlerearinginthenorthofEngland,andofthedairyindustryandspecializedproduce(suchashopsandcider)inotherareas.Improvementsintransport,includingthecoastalandrivertrade,providedaccesstonewmarkets.Newrotationsandcrops,particularlyclover,grassesandturnips,hadbeestablishedbytheendofthisperiodonthelightsoilsofEastAngliaandadoptedwithvaryingsuccessinotherpartsofthecountry.Thisperiodisstronglymarkedbythecontinuingprocessofenclosureandtherelatedprocessofexchangeandconsolidationoffarmholdings,thegrowthoffarmsize(especiallyincorn-producingareas),largeestatesandthewidespreaddevelopmentofalandlord–tenantsystem.Landowners,notablythecountygentry,emergedasinfluentialpioneersofnewcropsandnewsystemsoffarming.Theconsolidationofestatesandholdingsarereflectedinthecontinuing–andinmoreancientlyenclosedareasoftenthefinal–phaseofenclosure.Thenationalmarketbecamemoreintegratedfromthelater17thcentury,intandemwiththeemergenceofspecializedregionaleconomies.This,andthedevelopmentandstrengtheningoflocalbuildingtraditions,arealsoreflectedinthelayoutanddesignofbothfarmhousesandmoresubstantialfarmbuildings.

Agriculturalproductivitysustainedamassiveincreaseinpopulation,whichhadrisenfromaround6millionin1750toover16.7millionby1851and26millionin1881.Thiswasthemostimportantperiodoffarmbuildingdevelopment,monlydividedbyagriculturalhistoriansintotwoperiods:beforeandafter1840.Probablyunder25%ofthelandareaofEnglandremainedunenclosedby1750,andbetween1760and1815asmuchas18%ofthislandwasenclosed.ThiswasaprocessatfirstconcentratedontheMidlandclays(forthemanagementoflandaspastureforfattening)andthen–fromthestartoftheNapoleonicWarsinthe1790s–ontheexpansionofthecultivatedareaontopoorerandlightersoilssuchasthenorthernmoorlandsandthesoutherndownlands,andpoorly-drainedlandsuchastheFensandtheLancashiremosses.

Inthe‘HighFarming’yearsofthe1840sto1870s,high-inputorhigh-outputsystems–basedontheavailabilityofimportedartificialfertilizersandmanures(superphosphates,nitrates,guanoandbones)andfeedssuchasoilcakebroughtontothefarm–replacedthe‘closedcircuit’methodsthatreliedonfarm-producedfeedsandmanure.Amajordevelopment–asobservedbytheagriculturaljournalistJamesCairdwritinginthe1850s–wasanincreaseddistinctionbetweentheintensivelycroppedlandscapesoftheeasternhalfofthecountry,andthewetterandmorepastoral-basedeconomiesofthewesternhalf.

【托福高頻詞】

entitled

apaniedby

ceases

initially

spurred

associated

produce

rotations

notably

substantial

artificial

sustained

cultivated

distinction

【長難句分析】

InEnglishsocialandeconomichistory,enclosureistheprocesswhichendstraditionalrightssuchasmowingmeadowsforhay,orgrazinglivestockonmonlandformerlyheldintheopenfieldsystem.

Theprocessofenclosurehassometimesbeenapaniedbyforce,resistance,andbloodshed,andremainsamongthemostcontroversialareasofagriculturalandeconomichistoryinEngland.

ThiscreatedalandlessworkingclassthatprovidedthelaborrequiredinthenewindustriesdevelopinginthenorthofEngland.

LargerfarmersandlandownersinitiallybenefitedfromthegreatlandsalesthatfollowedtheDissolutionoftheMonasteriesinthe1530s,whilemostfarmersgainedfromrisingpricesandfavorableleases.

Newrotationsandcrops,particularlyclover,grassesandturnips,hadbeestablishedbytheendofthisperiodonthelightsoilsofEastAngliaandadoptedwithvaryingsuccessinotherpartsofthecountry.

ThiswasaprocessatfirstconcentratedontheMidlandclays(forthemanagementoflandaspastureforfattening)andthen–fromthestartoftheNapoleonicWarsinthe1790s–ontheexpansionofthecultivatedareaontopoorerandlightersoilssuchasthenorthernmoorlandsandthesoutherndownlands,andpoorly-drainedlandsuchastheFensandtheLancashiremosses.

2011年1月21日

【機經(jīng)簡述及學(xué)科知識】

嬰幼兒的記憶能力

記憶是人腦對過去經(jīng)驗的反映，記憶過程由四個部分構(gòu)成，它包括識記、保持、再認(rèn)和回憶四個基本環(huán)節(jié)。識記是獲得知識經(jīng)驗和鞏固知識經(jīng)驗的過程。例如，幼兒初次認(rèn)字，要通過反復(fù)多次的認(rèn)識，才把字記住，這是識記過程。保持是跟隨識記過程的，只要記住的字，總可保持一段時間。但保持的效果怎樣，則要通過再認(rèn)和回憶來檢驗。再認(rèn)是經(jīng)歷過的事物再次出現(xiàn)時，感到熟悉，能夠識別，再認(rèn)識。例如，認(rèn)過的字，再次出現(xiàn)能認(rèn)識。回憶是經(jīng)歷過的事物不在眼前時，根據(jù)一定的條件能把它重新反映出來。比如幼兒把玩具藏起來時會做個標(biāo)記，然后通過會議這些標(biāo)記找到所藏的東西。幼兒記憶就是由這樣四個相互聯(lián)系的過程組成的。

據(jù)研究表明，記憶的效果，隨年齡和經(jīng)驗的增長而增長，隨記憶材料性質(zhì)的不同而不同，一般到少年期達(dá)到高峰。有人做過這樣的實驗：用三組不同的材料，考察孩子的記憶能力，第一組材料是畫有具體實物圖形的圖片，第二組材料是畫有抽象圖形的圖片，第三組材料是詞。結(jié)果表明，對具體實物圖形的記憶能力在小學(xué)高年級時達(dá)到高峰，對抽象圖形和詞的記憶能力到初中階段，就是少年時期達(dá)到高峰。

人們一般認(rèn)為幼兒的記憶比成人更好，但事實上這是一種錯覺。例如，成人的生活領(lǐng)域廣闊，獲取經(jīng)驗的范圍極廣，工作、學(xué)習(xí)、生活中需要記憶的事情很多，為了保證記住主要的事情，常常對—些瑣碎的小事忽略而記不??；而孩子生活環(huán)境和經(jīng)驗范圍很小，活動中需要記住的事情相對較少，同時某些瑣碎小事反而常常是孩子感興趣的事情。如一些生活中的小物品，常常是孩于喜歡玩弄的，所以，當(dāng)成人忘記某些小東西的存放地點時，孩子就能告訴成人。

【英文題源】

Duringearliertimestherewasaconflictofbeliefbetweenparentsandresearchersaboutmemorystatusandskillstolearninchildren.Thoughparentsalwaysthoughtthatthechildlearnsandremembersatallages,butresearcherswereoftheopinionthatthechildhasnomemoryskilluptothetimethechildisofeightorninemonths.

Studyhasalsorevealedthatthechildhasmemoryevenwhenatthestageoffetus.Achildcanrememberanimpulsefromtenminutestotwentyfourhoursatdifferentstagesofdevelopmentasafetus.

Whatpsychologistshavedone,though,isexaminetheemergenceofmemoryinourfirstfewyearswithaseriesofnowclassicexperiments.Ifmemoriesreallycanbelaiddownearlyinlifethenitiscertainlypossibleintheoryforadultstorememberveryearlyexperiences.Oneclassicexperiment,devisedbyProfessorCarolynRovee-Collierandcolleaguesinthe1960s,providesusaninsightintowhatinfantscanremember.Thismethodhasproducedsomegreatevidenceabouthowandwheninfants'memoriesdevelop.Intheirexperiment,Roveehadinfantsofbetween9and12weekslayfortablyintheircribsathomelookingupatamobilecoveredwithbrightlycolouredwoodenfigures.Acordwasthenattachedtotheirfootconnectingittothemobile.Thismeantthatiftheinfantskickedoutthemobilewouldmove.And,iftheykickedouthard,thewoodenfigureswouldbumpintoeachotherandmakeapleasantknockingsound.Themorethelittlekidskick,themoreofakicktheygetfromthemobile.

Ifyou'restartingtogetawhiffofPavlovandhissalivatingdogthenyou'reontherightlines.Thisexperimentisallaboutseeingifaninfantcanbeconditionedtokicktheirfoottomakethemobilemove.Researchersfirstmeasureinfants'baselinelevelsofkicking(withmobileunattached),thenparethistokickingthatproducesanexcitingresponse.WhatRoveefoundwasthateveninfantsasyoungas8weeksoldcouldlearntheassociationbetweenkickingandthemobilemovement.Thislearningwasstillevidentovera45-55minutesperiod.

Whilethisinitialfindingisfairlymodest,theuseofthisprocedurehasledtoallsortsofnewfindingsaboutinfants'memories.Forexample,subsequentstudieshavelatersubstitutedadifferentmobilefortheoriginaltoseeiftheinfantscanspotthedifference,therebytestingwhetherornottheyreallyremember.

Inoneexperimentinfantsonly8-weeks-oldweretrainedwiththemobileoveraperiodof3daysfor9minuteseachday.Twenty-fourhourslatertheinfantsonlykickedatabovetheirbaselinelevelswhenthesamemobilewasabovetheirheads.Thisshowedtheyrememberedtheparticularmobiletheyhadbeentrainedwithandnotjustanyoldmobile.Itwasanespeciallyexcitingfindingbecauseithadpreviouslybeenthoughtthatlong-termmemory(and24hoursislong-termforpsychologists)didn'temergeuntilaslateas8or9months.

Becauseofthisexperimentandotherslikeit,wenowknowmuchmoreaboutinfantmemory.Ourmemorysystemsactuallyworkquitewellfromveryearlyon.Infants'memoriesalsoseemtoworkinmuchthesamewayasadultmemories-it'sjustthatinfantmemoriesaremuchmorefragile.

Roveearguesitisdoubtfulwhetherinfantileamnesiareallyexists.Itcertainlyappearsourbrainscanlaydownlong-termmemorieseveninthefirstyearoflife.Thereasonitisunusualtoretainmemoriesfromthattimeintoadulthoodisprobablybecauseofthelimitedcapacityofourearlymemorysystemsandtheinterveningyearsduringwhichweinevitablyforget.

【托福高頻詞】

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【長難句分析】

Subsequentresearchhasestablishedthatthebabyhasmemoryandcanretainathinginmemoryforadayattheageofsixweeksanduptoaperiodoffourmonthswhenattheageofeighteenmonths.

Thisexperimentisallaboutseeingifaninfantcanbeconditionedtokicktheirfoottomakethemobilemove.

Thereasonitisunusualtoretainmemoriesfromthattimeintoadulthoodisprobablybecauseofthelimitedcapacityofourearlymemorysystemsandtheinterveningyearsduringwhichweinevitablyforget.