Times Oldest Debate Essay Example For Students

Times Oldest Debate Essay Times Oldest DebateRaffikkiPeriod 2According to recent studies, planet earth formed approximately four and ahalf billion years ago. Since then, the earth has undergone many evolutionarychanges. Earth began as a swirling gas which condensed to create an immenseland mass. The ancient earth was basically the same as todays earth except forthe environment. The atmosphere of the ancient earth was quite different,containing more carbon and nitrogen gases than oxygen. The former atmosphere iswhere much of present day organic molecules such as proteins, lipids, andenzymes were created in abundance. By chance or simply because of the laws ofnature, those life producing compounds bonded together to create the oldestknown life form on earth a bacterium. Other life forms evolved from thebacterium through natural selection. These microscopic organisms formedsymbiotic relationships with each other and produced larger, multicellularorganisms, such as man. It may seem like a gigantic leap, bacteriu m to man, butgiven billions of years, it is certainly possible. It is true that The Bibleholds certain truths which would imply a reliable source of information; however,some parts of The Bible are not true at all. According to science, life evolvedin the following order: bacterium to fish, fish to various land animals, andanimals to man. Coincidentally or divinely, The Bible states that God said,Let the waters teem with fish and other lifelet the earth bring forth everykind of animalLet us make man (Genesis 1:20-26). The Bible accuratelydepicts the order in which life was established. But how could the primitivepeople who wrote The Bible know the order of which life was created withoutscience to aid them? This evidence would stand to prove that The Bible truly isthe word of God Himself. However, evolutionists would prefer to believe thatthe writer of The Bible was an incredible guesser. That is because many partsof The Bible seem to be written based on conjectures of what people of the timethought was correct. An example of this would be from Genesis, God made twogreat lights the greater light to govern the day and the lesser light togovern the night (Genesis 1:16). Obviously the greater light is the sun andthe lesser light is the moon; however, the moon is not a light, it is a planetthat reflects light. The people who wrote The Bible did not know that the moonwas a planet; nor did they know that other planets even existed. So, theydescribed the moon as a source of light just as the sun is a source of light. We will write a custom essay on Times Oldest Debate specifically for you for only $16.38 $13.9/page Order now The writers of The Bible made a good guess; nevertheless, they were wrong. Thisis not to say that the entire Bible is completely inaccurate, but explanationsconcerning the creation are a little vague. Such an unclear source should not beheld accountable to explain the origin of mankind. Other proof that the biblical account of creation is wrong lies withinthe process of carbon and uranium dating, and fossil records. Carbon dating isthe process of determining age by counting the amount of radioactive carbon in afossil or corpse. When a creature is living, it has a certain ratio ofradioactive carbon in it. That radioactive material decays at a fixed rate whenthe creature dies. Scientists know the fixed rate and can therefore determinehow old a carcass is by counting how much radioactive material remains insidethe carcass. Carbon dating is useful for dating remains less than fiftythousand years old. Using carbon dating, scientists have discovered fossils ofanimals that lived five times as long ago as creationists say is possible. .u84a66fb514d3155ebd8edb1277141003 , .u84a66fb514d3155ebd8edb1277141003 .postImageUrl , .u84a66fb514d3155ebd8edb1277141003 .centered-text-area { min-height: 80px; position: relative; } .u84a66fb514d3155ebd8edb1277141003 , .u84a66fb514d3155ebd8edb1277141003:hover , .u84a66fb514d3155ebd8edb1277141003:visited , .u84a66fb514d3155ebd8edb1277141003:active { border:0!important; } .u84a66fb514d3155ebd8edb1277141003 .clearfix:after { content: ""; display: table; clear: both; } .u84a66fb514d3155ebd8edb1277141003 { display: block; transition: background-color 250ms; webkit-transition: background-color 250ms; width: 100%; opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #95A5A6; } .u84a66fb514d3155ebd8edb1277141003:active , .u84a66fb514d3155ebd8edb1277141003:hover { opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #2C3E50; } .u84a66fb514d3155ebd8edb1277141003 .centered-text-area { width: 100%; position: relative ; } .u84a66fb514d3155ebd8edb1277141003 .ctaText { border-bottom: 0 solid #fff; color: #2980B9; font-size: 16px; font-weight: bold; margin: 0; padding: 0; text-decoration: underline; } .u84a66fb514d3155ebd8edb1277141003 .postTitle { color: #FFFFFF; font-size: 16px; font-weight: 600; margin: 0; padding: 0; width: 100%; } .u84a66fb514d3155ebd8edb1277141003 .ctaButton { background-color: #7F8C8D!important; color: #2980B9; border: none; border-radius: 3px; box-shadow: none; font-size: 14px; font-weight: bold; line-height: 26px; moz-border-radius: 3px; text-align: center; text-decoration: none; text-shadow: none; width: 80px; min-height: 80px; background: url(https://artscolumbia.org/wp-content/plugins/intelly-related-posts/assets/images/simple-arrow.png)no-repeat; position: absolute; right: 0; top: 0; } .u84a66fb514d3155ebd8edb1277141003:hover .ctaButton { background-color: #34495E!important; } .u84a66fb514d3155ebd8edb1277141003 .centered-text { display: table; height: 80px; padding-left : 18px; top: 0; } .u84a66fb514d3155ebd8edb1277141003 .u84a66fb514d3155ebd8edb1277141003-content { display: table-cell; margin: 0; padding: 0; padding-right: 108px; position: relative; vertical-align: middle; width: 100%; } .u84a66fb514d3155ebd8edb1277141003:after { content: ""; display: block; clear: both; } READ: Bipolar disorders EssayUranium dating is similar to carbon dating except that it is used for datingthings much older than fifty thousand years, such as the earth. Using uraniumdating, scientists have accurately calculated the age of the earth to be fourand a half billion years old and the age of the earliest living creature to bethree and a half billion years old (Campbell 505). Carbon and uranium datingfurnish indisputable evidence that the biblical account of creation is wrong andevolution has occurred. The most conclusive proof that man has evolved fromlower life forms lies within the physical characteristics of man and hisrelation to other creatures. One physical examp le that man evolved is thevarious stages of a developing embryo. For example, while a human is still inearly embryonic stages, it has gill slits. While the gill slits never fullymature, they serve as evidence that mans ancestors at one time had gills. During another period of embryonic development, a human has a tail. Sometimes,a human is actually born with a tail. The tail is evidence of a traitpreviously owned by an ancestor, but was discarded thousands of years ago. Thisis not to say that tails and other physical features are simply cast off, butafter years of disuse, a feature will grow smaller and eventually disappear. This is also evident in the growth of certain animals as well. At certainstages of development, the embryos of various mammals, birds, fish, and humansare indistinguishable. Further evidence suggesting evolution is vestigialorgans (organs that are of little or no use to the organism). For example,whales possess a pelvic bone which would serve a purpose for functioning legs,and yet they have no legs. Millions of years ago sea creatures came onto land,acquired legs, then returned to the sea where legs were not needed. The pelvicbone is vestigial in whales because it no longer serves a purpose. Another morefamiliar vestigial organ is the human appendix. It serves absolutely no purposeand, for some humans, is even removed. Embryonic proof, and vestigial organs aresufficient evidence that man has evolved from lower organisms. While creationists may believe evolution is wrong in defense of theirbelief in God, evolutionists have extensive evidence to strengthen their claimthat man is the result of evolution. Evolutionists say that man is a highlyevolved ape-like creature. There is scientific evidence to prove that claim. There is also proof that evolution is occurring today. Modern apes are aperfect example: they portray almost identical physical characteristics to thatof man, use tools, and are learning to speak using sign language. Apes are notonly similar to man physically and intellectually, but genetically as well. Human and ape DNA are ninety-nine percent identical. In fact, genetically,humans are more closely related to the ape than the ape is to the orangutan. Regardless of this scientific evidence, creationists will continue to believethat mankind was created by God. Of course, the creationists view only holdsif there is belief that The Bible is the true word of God. If mankind had nobelief in The Bibles account of creation, the Book would remain a work ofmythology. The Bible requires no ordinary belief, however, but a gigantic leapof faith because there is absolutely no evidence God created mankind. The onlyevidence of creation is in the opinions of millions of creationists.But ifopinion or belief were to be the only basis for determining human origin,couldnt mankind believe in literally anything and claim it for fact? Humanscould believe the mythical god, Zeus, created mankind! Its a sad truth, butcreationism is a relic in a world where the concept of evolution logicallyexplains the origin of mankind. .ub8a74567d368e02d316882ea838352d7 , .ub8a74567d368e02d316882ea838352d7 .postImageUrl , .ub8a74567d368e02d316882ea838352d7 .centered-text-area { min-height: 80px; position: relative; } .ub8a74567d368e02d316882ea838352d7 , .ub8a74567d368e02d316882ea838352d7:hover , .ub8a74567d368e02d316882ea838352d7:visited , .ub8a74567d368e02d316882ea838352d7:active { border:0!important; } .ub8a74567d368e02d316882ea838352d7 .clearfix:after { content: ""; display: table; clear: both; } .ub8a74567d368e02d316882ea838352d7 { display: block; transition: background-color 250ms; webkit-transition: background-color 250ms; width: 100%; opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #95A5A6; } .ub8a74567d368e02d316882ea838352d7:active , .ub8a74567d368e02d316882ea838352d7:hover { opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #2C3E50; } .ub8a74567d368e02d316882ea838352d7 .centered-text-area { width: 100%; position: relative ; } .ub8a74567d368e02d316882ea838352d7 .ctaText { border-bottom: 0 solid #fff; color: #2980B9; font-size: 16px; font-weight: bold; margin: 0; padding: 0; text-decoration: underline; } .ub8a74567d368e02d316882ea838352d7 .postTitle { color: #FFFFFF; font-size: 16px; font-weight: 600; margin: 0; padding: 0; width: 100%; } .ub8a74567d368e02d316882ea838352d7 .ctaButton { background-color: #7F8C8D!important; color: #2980B9; border: none; border-radius: 3px; box-shadow: none; font-size: 14px; font-weight: bold; line-height: 26px; moz-border-radius: 3px; text-align: center; text-decoration: none; text-shadow: none; width: 80px; min-height: 80px; background: url(https://artscolumbia.org/wp-content/plugins/intelly-related-posts/assets/images/simple-arrow.png)no-repeat; position: absolute; right: 0; top: 0; } .ub8a74567d368e02d316882ea838352d7:hover .ctaButton { background-color: #34495E!important; } .ub8a74567d368e02d316882ea838352d7 .centered-text { display: table; height: 80px; padding-left : 18px; top: 0; } .ub8a74567d368e02d316882ea838352d7 .ub8a74567d368e02d316882ea838352d7-content { display: table-cell; margin: 0; padding: 0; padding-right: 108px; position: relative; vertical-align: middle; width: 100%; } .ub8a74567d368e02d316882ea838352d7:after { content: ""; display: block; clear: both; } READ: The effects of the RussoJapanese War on WW1 EssayWorks CitedCampbell, Neil A. Biology Third Edition. California: The Benjamin/CummingsPublishing Company, Inc., 1993. The Living Bible: Paraphrased. 1971 ed. Wheaton, Illinois: Tyndale HousePublishers, 1971. Wertheim, Margaret. Science and Religion: Blurring the Boundaries.Omni Publications International, Ltd. October 1994: 36. Religion: SIRS, Vol. 4. 77. Religion

Etyka essays

Etyka essays 1. In my opinion, the young doctor did not do a right professional choice helping the police officer first. The professional choice should be made to the advantage of the gunman who was in the worse condition. A professional choice requires a doctor to chose a side of a person who is more seriously sick or injured regardless of other issues. On the other hand the doctor made a right moral decision because a policeman was an innocent man who also had family. If one of them would have to die it would be a right moral decision to save a person like the policeman with wife and children who need him than to save a worthless criminal who had no family to take care of. 2. I do not think that doctor Myricks experimentation is a noble guest. I think that taking homeless people from the street and experimenting on them causing a great pain or death are just to extreme way. However I can understand the need of sacrifice few people in order to help millions. In my opinion killing people is morally wrong and it does not matter who you kill. That is why I think that Dr. Myricks experimentation is not a noble guest. Maybe the alternative way would be to seek volunteers for such experiments who are for example sick with no chance for recovering. 3. Guys answer for the Dr. Myricks question is yes he would do anything to be able to walk again. This scene and particularly Dr. Myricks question is very important because it makes Guy and also viewers realize that he and probably we all in such situation would do anything to walk again, no matter if it would be morally right or wrong. 4. There is a connection between euthanasia that was performed by Guys father and the experiments of Dr. Myrick. The practices of both doctors (Dr. Myrick and Guys father) led to kill people. Most of religions puts peoples destiny in the hands of God and that is why both of them were pla ...

List of the 47 Prefectures of Japan by Area

List of the 47 Prefectures of Japan by Area Japan is an island nation located in eastern Asia in the Pacific Ocean. It is to the east of China, Russia, North Korea and South Korea. Japan is an archipelago that is made up of over 6,500 islands, the largest of which are Honshu, Hokkaido, Kyushu,  and Shikoku. It is one of the worlds largest countries by population and it has one of the largest economies in the world due to its many international companies and highly advanced technologies. Because of Japans large size, it is divided into 47 different prefectures for local administration (map). Prefectures in Japan are the highest level of government that an area can have as it is right below the federal government. They are similar to the 50 states of the United States and the 28 states of India or the provinces of Canada. Each prefecture has its own governor and they are subdivided into districts and municipalities. The following is a list of Japans prefectures by area. For reference, capital cities have also been included. 1) HokkaidoArea: 32,221 square miles (83,452 sq km)Capital: Sapporo2) IwateArea: 5,899 square miles (15,278 sq km)Capital: Morioka3) FukushimaArea: 5,321 square miles (13,782 sq km)Capital: Fukushima City4) NaganoArea: 4,864 square miles (12,598 sq km)Capital: Nagano5) NiigataArea: 4,857 square miles (12,582 sq km)Capital: Niigata6) AkitaArea: 4,483 square miles (11,612 sq km)Capital: Akita7) GifuArea: 4,092 square miles (10,598 sq km)Capital: Gifu8) AomoriArea: 3,709 square miles (9,606 sq km)Capital: Aomori9) YamagataArea: 3,599 square miles (9,323 sq km)Capital: Yamagata10) KagoshimaArea: 3,526 square miles (9,132 sq km)Capital: Kagoshima11) HiroshimaArea: 3,273 square miles (8,477 sq km)Capital: Hiroshima12) HyogoArea: 3,240 square miles (8,392 sq km)Capital: Kobe13) ShizuokaArea: 2,829 square miles (7,328 sq km)Capital: Shizuoka14) MiyagiArea: 2,813 square miles (7,285 sq km)Capital: Sendai15) KochiArea: 2,743 square miles (7,104 sq km)Capital: Kochi16) OkayamaArea: 2,706 square miles (7,008 sq km)Capital: Okayama17) KumamotoArea: 2,667 square miles (6,908 sq km)Capital: Kumamoto18) ShimaneArea: 2,589 square miles (6,707 sq km)Capital: Matsue19) MiyazakiArea: 2,581 square miles (6,684 sq km)Capital: Miyazaki20) TochigiArea: 2,474 square miles (6,408 sq km)Capital: Utsunomiya21) GunmaArea: 2,457 square miles (6,363 sq km)Capital: Maebashi22) YamaguchiArea: 2,359 square miles (6,111 sq km)Capital: Yamaguchi23) IbarakiArea: 2,353 square miles (6,095 sq km)Capital: Mito24) OitaArea: 2,241 square miles (5,804 sq km)Capital: Oita25) MieArea: 2,224 square miles (5,761 sq km)Capital: Tsu26) EhimeArea: 2,191 square miles (5,676 sq km)Capital: Matsuyama27) ChibaArea: 1,991 square miles (5,156 sq km)Capital: Chiba28) AichiArea: 1,990 square miles (5,154 sq km)Capital: Nagoya29) FukuokaArea: 1,919 square miles (4,971 sq km)Capital: Fukuoka30) WakayamaArea: 1,824 square miles (4,725 sq km)Capital: Wakayama31) KyotoArea: 1,781 square miles (4,613 sq km)Capital: Kyoto32) YamanashiArea: 1,724 square miles (4,465 sq km)Capital: Kofu33) ToyamaArea: 1,640 square miles (4,247 sq km)Capital: Toyama34) FukuiArea: 1,617 square miles (4,189 sq km)Capital: Fukui35) IshikawaArea: 1,616 square miles (4,185 sq km)Capital: Kanazawa36) TokushimaArea: 1,600 square miles (4,145 sq km)Capital: Tokushima37) NagasakiArea: 1,580 square miles (4,093 sq km)Capital: Nagasaki38) ShigaArea: 1,551 square miles (4,017 sq km)Capital: Otsu39) SaitamaArea: 1,454 square miles (3,767 sq km)Capital: Saitama40) NaraArea: 1,425 square miles (3,691 sq km)Capital: Nara41) TottoriArea: 1,354 square miles (3,507 sq km)Capital: Tottori42) SagaArea: 942 square miles (2,439 sq km)Capital: Saga43) KanagawaArea: 932 square miles (2,415 sq km)Capital: Yokohama44) OkinawaArea: 877 square miles (2,271 sq km)Capital: Naha45) TokyoArea: 844 square miles (2,187 sq km)Capital: Shinjuku46) OsakaArea: 731 square miles (1,893 sq km)Capital: Osaka47) KagawaArea: 719 square miles (1,862 sq km)Capital: Ta kamatsuSources:Wikipedia.org. Prefectures of Japan - Wikipedia, the Free Encyclopedia. Retrieved from: http://en.wikipedia.org/wiki/Prefectures_of_Japan.

The Song of Roland exemplifies model knightly behavior. What qualities Term Paper

The Song of Roland exemplifies model knightly behavior. What qualities were most desired in a knight What were the worst crimes - Term Paper Example The soldiers of the time had special titles, Knights that did not only highlight their proclaimed ability but also set them above the normal citizens. The knights went through a rigorous recruiting and training process that thereafter resulted in brave individuals who substituted their personal interests with the interest of the state and their divine call. The special soldiers had a specific age group and originated from specific families in the kingdom thus implying that the title of a knight preferred extraordinary personalities who had the heavenly selection. The early societies had an effective way of coercing loyalty using religions. By claiming that knights had some deific anointment, the soldiers therefore obeyed their leaders and followed their commands without questioning. The religions made knights brave enough to offer their lives in order to protect their kings and immediate leaders. The loyalty ensured discipline, which kept the military coherent enough to protect their internal interest. Ordinary soldiers who exhibited extraordinary skills and behavior would also graduate from their elementary roles in the military roles to become knight. However, such occasions were rare thereby making the few who would appear saintly. The details of the battle of Saragossa as depicted in the song of Roland reveal a number of qualities that made knights. One such quality is bravery. All knights would at one time fight in major battlefields. The wars of the time, unlike the modern art of warfare used less technology and soldiers had to interact using the rudimentary weapons. Several soldiers could therefore die in the process a feature that demanded extreme bravery. Knights swore to substitute their individual interests with those of their kingdoms a feature that still is desired in the earlier societies. The leaders of the societies managed to use religion among other divine features to foster the interest of the societies by making their knights willing to sacr ifice themselves simply to make the societies safer. In a great show of bravery, Roland a young man leads the rear of an entire army with only a handful man. His strong enemy overpower and threaten to kill him but he still refuses to call for held an act that would appear cowardly. He later blows his horn not to seek help from the bigger legion but to inform his leader of their predicament. In addition to bravery, knights required both obedience and loyalty. The military of the times just as still is today had a specific bureaucratic structures with each higher position demanding great respect, obedience and loyalty from their juniors. The knights followed and acted on orders without ever questioning the sources provided they came straight from their immediate seniors. Acts of disobedience were rare and would often attract harsh public punishments to instil both fear and discipline on the remaining soldiers. Obedience and loyalty aided the leaders control their troops, which constit uted of different people from diverse backgrounds. Before recruitment, the knights went through a rigorous training which aided instil the specific values and societal virtues into them. Additionally, the use of religion helped develop holistic armies united by the common respect for their leaders and nation through committing oaths, which they would not dare betray. Roland is a young man but holds a higher rank in the military, he uses his

Performance Measurement in a Post Merger Integration Process Essay

Performance Measurement in a Post Merger Integration Process - Essay Example The objective of any merger is to increase the value of the enterprise which means the there is always an objective that helps the company to come up with such a strategy to merger with another company. This is mostly seen as a long term strategy culminating from inside research in the market as there is not firm which would like to lose its identity in the market as a result of the merger. (ndrade 2001, p. 106; Ronald and Suzanne 2000, p. 5) In the recent past, there have been increasing interest on the issue of mergers. Many people have tried to look at the effect of those mergers in the face of looking who are the real winners and who are the real losers of merger. There have been many studies which have been looking closely into the issue of outcome of the mergers and acquisitions. The outcome of these two processes has been evaluated on many grounds from economic, communication, and other performance standards. (Caves 1999, p. 4; Lipin 2000, p.4) Once we realize that the objective of any merger is to increase the value of the enterprise in the market in order to create a formidable force the can compete effectively with others in the market, it will be easy for us to analyse then how does a merger affect the operation of each firms after they merge. This paper will concentrate on assessing the post merger effects on trust building performance and communication in the new enterprise. It will review various literature and findings that have come from many researches. (Ghosh 2001, p. 13) Outcome of mergers Many studies that have conducted research on mergers and acquisition have basically centred on some of the interesting characteristics of the mergers. They have been able to categorize the effect of merge on three broad classes. The first class consist of measureing performance after a merger based on share price. The second one has categories it on profitability while the class takes in many studied which have used other effect of merger success. (Paul 2002, p. 49) As we mentioned earlier the aim of any merger is to ensure that there is success of a business. This success should not only be measured in term of finical success but also in the degree of integration the two firms. In this regard cultural integration is one of the most important aspects that help the merger to succeed. Whether a merger can be considered a success based on the financial implication depends on many factors including the benchmark that is used to evaluate the merger. Many studies have concentrated on the share price of the firm pre and post merger as a measure of success in themes. This is often based on the confidence the investors will have on the merger. In this regard, the revenue of the firm is used as bench mark for evaluating the success of the firm since the dynamic trend in the share price of a firm will depend on the revenue collection of the firm. (Sitkin 1996, p. 17; Kaplan 2000, p. 243) Based on the financial performance of the mergers, studies that have been carried out shows that 82% of all mergers evaluated have shown success in the share price and economic performance. However it has also been shown that more that 50% of all mergers do not meet the expectations of the investors with majority of them failing to attain the objectives of the new merger. Once a merger is planned, there

Canterbury Tales - Wife of Bath :: essays papers

Canterbury Tales - Wife of Bath â€Å"The Prologue to the Canterbury Tales† had numerous unique characters, but the Wife of Bath struck me as the most interesting personality. Through the narrator’s use of direct and indirect characterization, significant details, and motivations for actions I was able to analyze the distinct traits of â€Å"the worthy woman from beside Bath city.† The narrator was very successful in portraying the wife. The wealth of the wife was distinct. â€Å"Her hose of finest scarlet red† shows the fortune she possesses. The wife also had enough fortune to travel to the most important shrines in Italy, France, Spain, and Germany. The narrator’s described her appearance well. â€Å"Bold was her face, handsome, and red in hue† allows the reader to picture the wife as an attractive woman of her time. The middle-aged woman had impressive large hips and â€Å"gap-teeth† which express lust. Her corpulent figure was a very favorable aspect of the time; it indicated wealth and beauty. â€Å"She’d had five husbands, all at the Church door† allows the reader to grasp much about the wife. Having five husbands shows that she is sociable and interested in love and marriage. Her experiences with marriage allow her to be very knowledgeable of love, which is â€Å"an art in which she knew the oldest dances.† â€Å"†¦ All at the Church door† shows her devotion to tradition and her faith. Her dedication to the Catholic Church and the forbidding Church rules of the time, allow the reader to infer she did not divorce her husbands. Therefore, all of her husbands passed away, which allows us to conclude she may have married older men. This wealthy world-traveler, on a pilgrimage to Canterbury, is not motivated by her faith as she travels on this mediocre trip.

Building a 21st Century Organization

The power and versatility of the human visual system derive in large part from its remarkable ability to find structure and organization in the images encoded by the retinas. To discover and describe structure, the visual system uses a wide array of perceptual organization mechanisms ranging from the relatively low-level mechanisms that underlie the simplest principles of grouping and segregation, to relatively high-level mechanisms in which complex learned associations guide the discovery of structure.The Gestalt psychologists were the first to fully appreciate the fundamental importance of perceptual organization (e. g. , see Kohler, 1947; Pomerantz & Kubovy, 1986). Objects often appear in different contexts and are almost never imaged from the same viewpoint; thus, the retinal images associated with physical objects are generally complex and varied. To have any hope of obtaining a useful interpretation of the retinal images, such as recognizing objects that have been encountered p reviously, there must be initial processes that organize the image data into those groups most likely to form meaningful objects.Perceptual organization is also important because it generally results in highly compact representations of the images, facilitating later processing, storage, and retrieval. (See Witkin & Tenenbaum, 1983, for a discussion of the importance of perceptual organization from the viewpoint of computational vision. ) Although much has been learned about the mechanisms of perceptual organization (see, e. g. , Beck, 1982; Bergen, 1991; Palmer & Rock, 1994; Pomerantz & Kubovy, 1986), progress in developing testable quantitative theories has been slow.One area where substantial progress has been made is in models of texture grouping and segregation. These models have begun to put the study of perceptual organization on a firm theoretical footing that is consistent with the psychophysics and physiology of low-level vision. Two general types of model for texture segr egation have been proposed. In the feature-based models, retinal images are initially processed by mechanisms that find specific features, such as edge segments, line segments, blobs, and terminators.Grouping and segregation are then accomplished by finding the image regions that contain the same feature or cluster of features (see, e. g. , Julesz, 1984, 1986; Marr, 1982; Treisman, 1985). These models are relatively simple, are consistent with some aspects of low-level vision, and have been able to account for a range of experimental results. In the filter-based models, retinal images are initially processed by tuned channels, for example, â€Å"contrast-energy† channels selective for size and orientation.Grouping and segregation are then accomplished by finding those image regions with approximately constant output from one or more channels (Beck, Sutter, & Ivry, 1987; Bergen & Landy, 1991; Bovik, Clark, & Geisler, 1990; Caelli, 1988; Chubb & Sperling, 1988; Clark, Bovik, & Geisler, 1987; Fogel & Sagi, 1989; Graham, Sutter, & Venkatesan, 1993; Victor, 1988; Victor & Conte, 1991; Wilson & Richards, 1992).These models have some advantages over the existing feature-based models: They can be applied to arbitrary images, they are generally more consistent with known low-level mechanisms in the visual system, and they have proven capable of accounting for a wider range of experimental results. However, the current models do not make accurate predictions for certain important classes of stimuli. One class of stimuli are those that contain regions of texture that can be segregated only on the basis of local structure (i. e. , shape).Another broad class of stimuli for which most current perceptual organization models do not make adequate predictions are those containing nonstationary structures; specifically, structures that change smoothly and systematically across space. Nonstationary structures are the general rule in natural images because of perspective pr ojection, and because many natural objects are the result of some irregular growth or erosion process. A simple example of a nonstationary structure would be a contour formed by a sequence of line segments (a dashed contour) embedded in a background of randomly oriented line segments.Such contours are usually easily picked out by human observers. However, the elements of the contours cannot be grouped by the mechanisms contained in current filter-based or feature-based models, because no single orientation channel or feature is activated across the whole contour. Grouping the elements of such contours requires some kind of contour integration process that binds the successive contour elements together on the basis of local similarity. A more complex example of a nonstationary structure would be an image of wood grain.Such a texture contains many contours whose spacing, orientation, and curvature vary smoothly across the image. Again, such textures are easily grouped by human observe rs but cannot be grouped by the mechanisms contained in the current models. Grouping the contour elements of such textures requires some form of texture integration (the two-dimensional analogue of contour integration). The heart of the problem for existing quantitative models of grouping and segregation is that they do not represent the structure of the image data with the richness achieved by the human visual system.The human visual system apparently represents image information in an elaborate hierarchical fashion that captures many of the spatial, temporal, and chromatic relationships among the entities grouped at each level of the hierarchy. Grouping and segregation based on simple feature distinctions or channel responses may well be an important initial component of perceptual organization, but the final organization that emerges must depend on more sophisticated processes.The major theoretical aim of this study was to develop a framework for constructing and testing models o f perceptual organization that capture some of the richness and complexity of the representations extracted by the human visual system, and yet are computationally well defined and biologically possible. Within this framework, we have developed a model of perceptual organization for two-dimensional (2D) line images and evaluated it on a number of â€Å"textbook† perceptual organization demonstrations.In this article we refer to this model as the extended model when it is necessary to distinguish it from a simplified version, the restricted model, described later. Perceptual organization must depend in some way on detected similarities and differences between image elements. Furthermore, it is obvious that similarities and differences along many different stimulus dimensions can contribute to the organization that is perceived. Although there have been many studies of individual stimulus dimensions, there have been few systematic attempts to study how multiple dimensions inter act (Beck et al., 1987; Fahle & Abele, 1996; Li & Lennie, 1996). The major experimental aim of this study was to measure how multiple stimulus dimensions are combined to determine grouping strength between image elements. To this end, we conducted a series of three-pattern grouping experiments to directly measure the tradeoffs among two, three, or four stimulus dimensions at a time. Predictions for these experiments were generated by a restricted version of the model appropriate for the experimental task. The experimental results provided both a test for the restricted model and a means of estimating the model's parameters.The estimated parameter values were used to generate the predictions of the extended model for complex patterns. The next four sections describe, respectively, the theoretical framework, the restricted model, the experiments and results, and the extended model and demonstrations. Theoretical Framework for Perceptual Organization In this section we discuss four imp ortant components of perceptual organization: hierarchical representation, detection of primitives, detection of similarities and differences among image parts, and mechanisms for grouping image parts.These components taken together form the theoretical framework on which the restricted and extended quantitative models are based. Hierarchical Representation It is evident that the mechanisms of perceptual organization yield a rich hierarchical representation that describes the relationship of â€Å"parts† to â€Å"wholes† at a number of levels; that is, the wholes at one level often become the parts at the next level. However, there is evidence that the process by which the hierarchical representation is constructed does not proceed strictly either from local to global or from global to local.The global structure of a large letter composed of small letters can be discovered before the structure of the individual small letters is discovered (Navon, 1977), and there exist ambiguous figures, such as R. C. James's classic Dalmatian dog, that can be solved locally only after at least some of the global structure is discovered. On the other hand, the discovery of structure must sometimes proceed from local to global; for example, it would be hard to extract the symmetry of a complex object without first extracting some of the structure of its subobjects.Any well-specified theory of perceptual organization must define what is meant by parts, wholes, and relationships between parts and wholes. Given the current state of knowledge, all definitions, including the ones we have adopted, must be tentative. Nonetheless, some basic definitions must be made in order to form working models. In our framework, the most primitive objects are defined on the basis of the current understanding of image encoding in the primary visual cortex of the primate visual system.Higher order objects are defined to be collections of lower order objects (which may include primitive objects), together with information about the relationships between the lower order objects. The range of relationships that the visual system can discover, the order and speed with which they are discovered, and the mechanisms used to find them are unsettled issues. As a starting point the relationships we consider are quantitative similarities and differences in size, position, orientation, color, and shape.These dimensions were picked for historical and intuitive reasons: They are major categories in human language and therefore are likely to correspond to perceptually important categories. The precise definitions of these dimensions of similarity between objects are given later. Detection of Primitives: Receptive-Field Matching One of the simplest mechanisms for detecting structure within an image is receptive-field matching, in which relatively hard-wired circuits are used to detect the different spatial patterns of interest.For example, simple cells in the primary visual corte x of monkeys behave approximately like hard-wired templates: A strong response from a simple cell indicates the presence of a local image pattern with a position, orientation, size (spatial frequency), and phase (e. g. , even or odd symmetry) similar to that of the receptive-field profile (Hubel & Wiesel, 1968; for a review, see DeValois & DeValois, 1988). The complex cells in the primary visual cortex are another example.A strong response from a typical complex cell indicates a particular position, orientation, and spatial frequency independent of the spatial phase (Hubel & Wiesel, 1968; DeValois & DeValois, 1988). Receptive field matching may occur in areas other than the primary visual cortex, and may involve detection of image structures other than local luminance or chromatic contours, for example, structures such as phase discontinuities (von der Heydt & Peterhans, 1989) and simple radially symmetric patterns (Gallant, Braun, & Van Essen, 1993).An important aspect of receptive -field matching in the visual cortex is that the information at each spatial location is encoded by a large number of neurons, each selective to a particular size or scale. The population as a whole spans a wide range of scales and hence provides a â€Å"multiresolution† or â€Å"multiscale† representation of the retinal images (see, e. g. , DeValois & DeValois, 1988). This multiresolution representation may play an important role in perceptual organization.For example, grouping of low-resolution information may be used to constrain grouping of high-resolution information, and vice versa. The quantitative models described here assume that receptive-field matching provides the primitives for the subsequent perceptual organization mechanisms. However, to hold down the complexity of the models, the receptive-field matching stage is restricted to include only units similar to those of cortical simple cells with small receptive fields. These units proved sufficient for the line pattern stimuli used in the experiments and demonstrations.Receptive-field matching is practical only for a few classes of simple image structure, such as contour segments; it is unreasonable to suppose that there are hard-wired receptive fields for every image structure that the visual system is able to detect, because of the combinatorial explosion in the number of receptive-field shapes that would be required. Thus, there must be additional, more flexible, mechanisms for detecting similarities and differences among image regions. These are discussed next. Similarity/Difference Detection MechanismsStructure exists within an image if and only if some systematic similarities and differences exist between regions in the image. Thus, at the heart of any perceptual organization system there must be mechanisms that match or compare image regions to detect similarities and differences. (For this discussion, the reader may think of image regions as either parts of an image or as grou ps of detected primitives. ) Transformational matching A well-known general method of comparing image regions is to find out how well the regions can be mapped onto each other, given certain allowable transformations (see, e.g. , Neisser, 1967; Pitts & McCulloch, 1947; Rosenfeld & Kak, 1982; Shepard & Cooper, 1982; Ullman, 1996). The idea is, in effect, to use one image region as a transformable template for comparison with another image region. If the regions closely match, following application of one of the allowable transformations, then a certain similarity between the image regions has been detected. Furthermore, the specific transformation that produces the closest match provides information about the differences between the image regions.For example, consider an image that contains two groups of small line segment primitives detected by receptive-field matching, such that each group of primitives forms a triangle. If some particular translation, rotation, and scaling of one of the groups brings it into perfect alignment with the other group then we would know that the two groups are identical in shape, and from the aligning transformation itself we would know how much the two groups differ in position, orientation, and size. There are many possible versions of transformational matching, and thus it represents a broad class of similarity-detection mechanisms.Transformational matching is also very powerful—there is no relationship between two image regions that cannot be described given an appropriately general set of allowable transformations. Thus, although there are other plausible mechanisms for detecting similarities and differences between image regions (see section on attribute matching), transformational matching is general enough to serve as a useful starting point for developing and evaluating quantitative models of perceptual organization. Use of both spatial position and colorThe most obvious form of transformational matching is based on standard template matching; that is, maximizing the correlation between the two image regions under the family of allowable transformations. However, template matching has a well-known limitation that often produces undesirable results. To understand the problem, note that each point in the two image regions is described by a position and a color. The most general form of matching would consist of comparing both the positions and colors of the points. However, standard template matching compares only the colors (e. g. , gray levels 2 ) at like positions.If the points cannot be lined up in space then large match errors may occur even though the positional errors may be small. A more useful and plausible form of matching mechanism would treat spatial and color information more equivalently by comparing both the spatial positions and the colors of the points or parts making up the objects. For such mechanisms, if the colors of the objects are identical then similarity is determined solely by how well the spatial coordinates of the points or parts making up the objects can be aligned and on the values of the spatial transformations that bring them into the best possible alignment.In other words, when the colors are the same, then the matching error is described by differences in spatial position. For such mechanisms, B matches A better than B matches C, in agreement with intuition. Later we describe a simple matching mechanism that simultaneously compares both the spatial positions and the colors of object points. We show that this mechanism produces matching results that are generally more perceptually sensible than those of template matching. Attribute matchingAnother well-known method of comparing groups is to measure various attributes or properties of the groups, and then represent the differences in the groups by differences in the measured attributes (see, e. g. , Neisser, 1967; Rosenfeld & Kak, 1982; Selfridge, 1956; Sutherland, 1957). These attributes might be simple measures, such as the mean and variance of the color, position, orientation, or size of the primitives in a group, or they might be more complex measures, such as the invariant shape moments. It is likely that perceptual organization in the human visual system involves both transformational matching and attribute matching.However, the specific models considered here involve transformational matching exclusively. The primary reason is that perceptual organization models based on transformational matching have relatively few free parameters, yet they are sensitive to differences in image structure—an essential requirement for moving beyond existing filter- and feature-based models. For example, a simple transformational matching mechanism (described later) can detect small differences in arbitrary 2D shapes without requiring an explicit description of the shapes.On the other hand, specifying an attribute-matching model that can detect small differences in arbitr ary shapes requires specifying a set of attributes that can describe all the relevant details of arbitrary shapes. This type of model would require many assumptions and/or free parameters. Our current view is that transformational matching (or something like it) may be the central mechanism for similarity/difference detection and that it is supplemented by certain forms of attribute matching. Matching groups to categoriesThe discussion so far has assumed implicitly that transformational and attribute matching occur between different groups extracted from the image. However, it is obvious that the brain is also able to compare groups with stored information because this is essential for memory. Thus, the visual system may also measure similarities and differences between groups and stored categories, and perform subsequent grouping using these similarities and differences. These stored categories might be represented by prototypes or sets of attributes.Rather than use stored categori es, the visual system could also measure similarities and differences to categories that emerge during the perceptual processing of the image. For example, the visual system could extract categories corresponding to prevalent colors within the image, and then perform subsequent grouping on the basis of similarities between the colors of image primitives and these emergent color categories. Grouping Mechanisms Once similarities and differences among image parts are discovered, then the parts may be grouped into wholes.These wholes may then be grouped to form larger wholes, resegregated into a different collection of parts, or both. However, it is important to keep in mind that some grouping can occur before all of the relevant relationships between the parts have been discovered. For example, it is possible to group together all image regions that have a similar color, before discovering the geometrical relationships among the regions. As further relationships are discovered, the rep resentations of wholes may be enriched, new wholes may be formed, or wholes may be broken into new parts and reformed.Thus, the discovery of structure is likely to be an asynchronous process that operates simultaneously at multiple levels, often involving an elaborate interleaving of similarity/difference detection and grouping. Within the theoretical framework proposed here we consider one grouping constraint—the generalized uniqueness principle—and three grouping mechanisms: transitive grouping, nontransitive grouping, and multilevel grouping. The uniqueness principle and the grouping mechanisms can be applied at multiple levels and can be interleaved with similarity/difference detection.Generalized uniqueness principle The uniqueness principle proposed here is more general: it enforces the constraint that at any time, and at any level in the hierarchy, a given object (part) can be assigned to only one superordinate object (whole). An object at the lowest level (a pr imitive) in the hierarchy can be assigned to only one object at the next level, which in turn can be assigned to only one object at the next level, and so on. The sequence of nested objects in the hierarchy containing a given object is called the part–whole path of the object.The generalized uniqueness principle, if valid, constrains the possible perceptual organizations that can be found by the visual system. Nontransitive grouping Our working hypothesis is that similarity in spatial position (proximity) contributes weakly to nontransitive grouping. If proximity were making a dominant contribution, then separated objects could not bind together separately from the background objects. 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