Why is Hubel and Wiesels Description of the Classical...

The ultimate goal for a system of visual perception is representing visual scenes. It is generally assumed that this requires an initial ‘break-down’ of complex visual stimuli into some kind of â€Å"discrete subunits† (De Valois De Valois, 1980, p.316) which can then be passed on and further processed by the brain. The task thus arises of identifying these subunits as well as the means by which the visual system interprets and processes sensory input. An approach to visual scene analysis that prevailed for many years was that of individual cortical cells being ‘feature detectors’ with particular response-criteria. Though not self-proclaimed, Hubel and Wiesel’s theory of a hierarchical visual system employs a form of such feature detectors. I†¦show more content†¦Applying this notion to mammalian vision is however problematic; humans for example, are capable of visually perceiving greater detail and variety than a frog and would thus require considerably more of these uniquely coded feature detectors. The notion of a ‘grandmother cell’ was thus introduced to highlight the entailment of such a theory; if every unique stimulus requires its own feature-detector cell, an absurdly high number of neurons would be required for humans to represent the vast variety of visual scenes encountered in a lifetime. Aware of this shortcoming, Hubel and Wiesel (1962,1965,1968) were cautious not refer to ‘feature detectors’ when examining the receptive fields of the mammalian visual cortex of live cats (Hubel Wiesel, 1962) and monkeys (Hubel Wiesel, 1968). Nonetheless, it is now widely accepted that Hubel and Wiesel’s theory of simple, complex and hyper-complex cells remains a form of the original feature-detector theory, albeit formulated into a more economical hierarchical structure. (Lennie, 2003; Martin, 1994) Hubel and Wiesel (962, 1965) concluded that vision involved a hierarchical process starting in the retina, continuing through the lateral geniculate body, the primary visual cortex and possibly even into areas V2 and V3. As sensory information travels further up the hierarchy, it passes through progressively higher-order cells that become increasingly

The Slave Crucible Analysis - 1266 Words

â€Å"The Slave Crucibles† and â€Å"A Federal Assault† provide different perspectives on the experiences of slaves. â€Å"The Slave Crucibles† contributes personal insight into the different aspects of the lives of slaves while â€Å"A Federal Assault† exhibits a generalized viewpoint on the effects of laws such as the Fugitive Slave Act of 1850 on the majority of the slave population. Both pieces of literature demonstrate the injustices and demeaning treatment towards African Americans during the 19th century. Pargas’ â€Å"The Slave Crucibles† is structured to provide the personal experiences of slaves by including specific examples and testimonies from those who endured slavery or had first hand encounters with enslaved African Americans. By including such†¦show more content†¦However, fictive kin and these new established relationships on shared experiences did not completely extinguish the feelings of longing for loved ones or diminish the oppression faced by these people. Reunion with family members was one of the major motives for interstate migrants to escape but sometimes it proved to be more difficult than expected because migrants came from longer distances. Therefore, when attempts to escape were made they were more permanent and â€Å"...fugitives were not intending to ‘visit’ loved ones but rather escape their new destinations for good†¦Ã¢â‚¬  (Pargas 243). These feelings of depression and isolation, removal from loved ones, and demeaning treatment incited many slaves to escape. Escaping was never easy and there were laws set in place to punish those who tried to do so. These laws, specifically the Fugitive Slave Act of 1850, and their effects are closely examined in Horton’s article, â€Å"A Federal Assault.† Horton provides a more generalized approach and the use of anecdotes is present but is not as intense as in â€Å"The Slave Crucibles.† Horton presents the actions taken by the government and the states in order to deal with fugitives. He examines the impact of the Fugitive Slave Act of 1850 on the general slave population and the people associated with it. Information is also presented on what was done in order to combat the Fugitive Slave Act and allow African Americans to experience the freedom that theyShow MoreRelatedAccusation And Defense Of The Salem Witchcraft Trials1658 Words   |  7 PagesHistory 1301-73001-73002 JOE L. MCCAMBRIDGE - HISTORY 1301-1302 One of the most infamous Trial in history took place on March 1, 1692. According, to the Library of Congress, Massachusetts authorities catechized Sarah Good, Sarah Osborne, and an Indian Slave, Tituba regarding their practice in witchcraft. The trial resulted in more than 150 men and women in and around Salem jailed on charges of practicing Witchcraft and Sorceries. 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Reflecting this tactic, cases involving slavery and the treatment of slaves rarely made it into the courtroom, although it was constantly at the forefront of the court of public opinion. It seemed that everyone desired to keep enslavement as it was, for fear of ruffling the feathers of some dangerous birds. America was, atRead MoreRace And Gender Politics : Purple Hibiscus1487 Words   |  6 Pagesand inequality of class and culture. From there, I hoped to comprehend how gender politics was a reflection of Nigerian politics and its gender perceptions in the social structure as a whole. As my work proceeded, however, a third dimension of analysis became equally significant, for it became clear that, as much as African women in this novel speak from physical environments shaped by race, there is also an element of silence, censorship and domestic violence. The narrative of this novel, theRead MoreRhetorical Analysis Of Winthrop Delivered Sermon Called A Modell Of Christian Charity2205 Words   |  9 Pagesin Bradford s piece, it becomes the main point of interest and analysis as I read it. Have you ever watched an award show, and when someone wins an Oscar, Grammy, Tony, etc., they thank God, and you wonder why they would blindly attribute their remarkable successes to something so intangible? That s what I was thinking when I read this short section, and that s why I chose to include the first quote in this reflection and analysis. The pilgrims give all the credit to God for their survival acrossRead MoreSupernatural in American Fiction Essay2928 Words   |  12 PagesMankind would never submit to this. He will immediately turn to the darkness. Drawn by his own cords of fear and longing, man will imagine that he is tired of the light and his small, familiar world.3 No amount of rationalization... or Freudian analysis can overcome the thrill of the chimney-corner whisper or the lonely wood.4 Why? Children will always be afraid of the dark and men will always shudder at what they do not understand, yet everyone will continue to seek it. Perhaps it is becauseRead MoreEssay The Salem Witchcraft Trials of 16924260 Words   |  18 Pagesgovernment in Africa, Salem town council in Salem village), and new opportunities for betterment which are not evenly distributed throughout the population, causing increased social inequality. There have been three basic approaches taken to the analysis of the Salem witch trials. Scholars have sought psychological and biological explanations for the symptoms displayed by the bewitched girls. Sexual repression in Puritan New England, the low status of women, especially young women, in the community

SON OF A SMALLER HERO by Mordecai Richler Essay Example For Students

SON OF A SMALLER HERO by Mordecai Richler Essay What is the central truth about people in the novel?I think the central truth that Richler writes about in this novel concerns our right to be happy. In the novel we witness the main characters suffering because of the fear to protect their rights. One of the brightest examples is Melech. On one hand he is presented as a stern and ambitious character who isnt afraid to accept a challenge. In pursuit of happiness he leaves his homeland and comes to Canada with only fifty cents. He makes a living working in the scrap yard and still he can afford to have ten children. It seems that he succeeded in life, but on the other hand he isnt happy at all. At the end he feels guilty about his Polish girlfriend who he misses all his life. He and she truly loved each other, but Melech was too afraid to rebel against his family which forbade him to marry her. A similar situation happens to his oldest son, Wolf. Unlike his father, he is a small man who accomplished nothing in life. He works in Melech s scrap yard and cant do anything about his miserable life. Being always afraid of Melech, he has to marry against his will. Later he even has to make a child because Melech tells him to. Submitting to his father, Wolf voluntarily gives away his freedom and turns his life into a torture. It seems that fear to stick up for ones own rights is a common problem in the Adlers family. In this case Noah is represented as a hero and an example to be followed. Living in the Jewish community he cant afford to be a loser and an embarrassment to his family. He knows what is right for him, and sets off into the gentile world, even if its different and against the laws of his grandfather. He failed to be a real Jew, but partly it happened by his initiative. He wanted to be someone different, may be better or worse for him, but still someone. Unlike both of his predecessors, he is natural and rebels for his rights. Through his example, Richler suggests that for any human being there are things tha t are much more important than laws.

Laboratory Techniques and Measurements Lab 1 (Labpaq) free essay sample

Throughout lab one we were introduced to many different forms of measurement, whether its using a ruler too measure length, a digital scale to measure weight, and also many different sized and shaped flasks to measure different volumes. Another key measurement of this lab was to teach the student about density and how to measure it. Density tells us that it is defined as the mass per unit measure, in which as we know is most oven referred to as volume and is also used to describe how heavy something is. We were also required to calculate many different measurements do to the number of moles that one substance might have due to the amount of material/solution we are currently working with. Along with all the measurements and how to use them correctly that Lab 1 teaches us, it also presents to use how to record our data correctly using Significant Figures. We will write a custom essay sample on Laboratory Techniques and Measurements Lab 1 (Labpaq) or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Significant figures are the number of digits that we may use including or excluding the zeros that we may be given with any number or solution. There are many different rules in determining the proper number of significant figure in an answer. For example; â€Å"All zeros to the right of the decimal place and to the right of a non zero digit are consider significant†. So we were given the number 45. 000, we know from the rule above that this figure has 5 significant figures because the zeros following he unit are behind the decimal place and are considered significant. My Hypothesis for this lab was simple, can I or can I not make the proper measurements using the provided materials and measuring devices included for this lab. Along with making the appropriate measurements, will I be able to use the rules I was taught and record my data with the correct significant figures? This lab is all about measurements and recording them properly. The lab first introduces to use the measurement of centimeters, millimeters, and meters to measure different household objects in our everyday life. We were given the task to use the provided ruler and measure a CD, key, spoon, and a fork in centimeters and then convert our findings to give us the appropriate units of millimeters and meters for each object required in the exercise. Data Table 1: Length measurements. | Object| Length (cm)| Length (mm)| Length (m)| CD or DVD| 12cm| 120mm| . .12m| Key| 5. 5cm| 55mm| 0. 055m| Spoon| 15cm | 150mm| . 15m| Fork| 18cm| 180mm| . 18m| Lab 1 also teaches us the importance of molecular weight of a substance and how to use that to find the amount of moles of that substance in a solution. For example; in exercise 3 we were asked to weigh 8 grams of sugar and then calculate how many moles of sugar it really was. Using the molecular weight of sugar (C = 12. 01 grams/mol, H = 1. 008 grams/mole, O = 15. 00 grams/mole). We were then able to use this molecular mass of the sugar that we then had to use to calculate and determine the molarity of the sugar solution that we were working on for exercise three. Data Table 8: Initial Concentration. | Chemical| Mass(g)| Molecular Weight (g)| Moles in Volumetric Flask| Total Volume (L)| Molarity(mol/L)| Sugar(C12H22O11)| 8. g8. | 28. 018g| 0. 29 | . 0025L| 116 mol/L| My analyses of this lab is like so. The lab presented itself with great learning options for teaching us how to use and proper measure the different units of the Si system, but as easy as they are to learn there are many of possible solutions for error. Since this was the first lab the many of the students have probably done in a couple years, I see plenty of room for h uman error do to the lack of training or experience with most of the lab equipment required to compete this lab to the full. Not only is there room for human error but there are also the possibilities of error with the lab equipment whether it is the student’s fault or just default equipment. For example, if the digital scale, required for most of the lab, is not tarred right, your numbers from your experiment are going to be way off. One wrong calculation or measurement could ruin a whole exercise if not whole entire lab itself. In my conclusion for this lab was pretty accurate to my hypothesis. I was able to make most of the appropriate measurements with little to no error at all. I had trouble with the density at first seeing I have never used the method for calculating density. After a few tries I was able to succeed in calculating all the appropriate calculation required for this lab as well as using the appropriate significant figures for all my answers in my lab right up. Measurements are all around us in our daily life. We use some sort of measurement on a daily bases whether we know it or not. Without measurement or the SI units we would have no since of idea of how much something may way or weather or not the water was going to fit into a single are or space (density). The unit of measure is used so much throughout the world everyday that without it, the world would have no since of weight, mass, height, width, or any other unit from the Si family. We use this form of description for almost everything living and non-living in our world today.