That essay provided information concerning the various aspects of school context and the leader's role in shaping a school context that is conducive to change.
Visual system The visual system in animals allows individuals to assimilate information from their surroundings.
The act of seeing starts when the cornea and then the lens of the eye focuses light from its surroundings onto a light-sensitive membrane in the back of the eye, called the retina. The retina is actually part of the brain that is isolated to serve as a transducer for the conversion of light into neuronal signals.
Based on feedback from the visual system, the lens of the eye adjusts its thickness to focus light on the photoreceptive cells of the retina, also known as the rods and cones, which detect the photons of light and respond by producing neural impulses.
These signals are processed via complex feedforward and feedback processes by different parts of the brain, from the retina upstream to central ganglia in the brain. Note that up until now much of the above paragraph could apply to octopusesmolluskswormsinsects and things more primitive; anything with a more concentrated nervous system and better eyes than say a jellyfish.
However, the following applies to mammals generally and birds in modified form: The retina in these more complex animals sends fibers the optic nerve to the lateral geniculate nucleusto the primary and secondary visual cortex of the brain.
Signals from the retina can also travel directly from the retina to the superior colliculus. The perception of objects and the totality of the visual scene is accomplished by the visual association cortex.
The visual association cortex combines all sensory information perceived by the striate cortex which contains thousands of modules that are part of modular neural networks.
The neurons in the striate cortex send axons to the extrastriate cortexa region in the visual association cortex that surrounds the striate cortex.
Two-streams hypothesis The major problem in visual perception is that what people see is not simply a translation of retinal stimuli i. Thus people interested in perception have long struggled to explain what visual processing does to create what is actually seen.
Early studies[ edit ] The visual dorsal stream green and ventral stream purple are shown. Much of the human cerebral cortex is involved in vision. There were two major ancient Greek schools, providing a primitive explanation of how vision is carried out in the body.
The first was the " emission theory " which maintained that vision occurs when rays emanate from the eyes and are intercepted by visual objects. If an object was seen directly it was by 'means of rays' coming out of the eyes and again falling on the object.
A refracted image was, however, seen by 'means of rays' as well, which came out of the eyes, traversed through the air, and after refraction, fell on the visible object which was sighted as the result of the movement of the rays from the eye.
This theory was championed by scholars like Euclid and Ptolemy and their followers. The second school advocated the so-called 'intro-mission' approach which sees vision as coming from something entering the eyes representative of the object.
With its main propagators AristotleGalen and their followers, this theory seems to have some contact with modern theories of what vision really is, but it remained only a speculation lacking any experimental foundation.
Plato makes this assertion in his dialogue Timaeusas does Aristotlein his De Sensu. The eye has a central line and everything that reaches the eye through this central line can be seen distinctly.
Alhazen — c. He wrote "The function of the human eye But I found it to be completely different. Although he did not use these words literally he actually is the father of the modern distinction between foveal and peripheral vision.
Unconscious inference Hermann von Helmholtz is often credited with the first study of visual perception in modern times. Helmholtz examined the human eye and concluded that it was, optically, rather poor.
The poor-quality information gathered via the eye seemed to him to make vision impossible.Resources for School Librarians - Index.
School Library Mission Statements, Action Plans, Action Research, and Annual Reports. Menu for this page: Mission Statements | Action Plans | Action Research | Annual Reports Today it seems that accountability is the hot topic in educational reform.
Jul 09, · How to Write a Problem Statement. In this Article: Article Summary Sample Problem Statements Writing Your Own Problem Statement Polishing Your Problem Statement Community Q&A A problem statement is a short, succinct explanation of a problem a business is facing and a proposed solution to the problem.
The vision derived from this process serves as a beacon, lighting the way for organizational members to collaborate on behalf of students. Closely related to the vision statement is the mission for the school. Many schools today are prioritizing accommodations for students with disabilities, including visual disabilities.
Learn how high schools, colleges and other institutions use simple technology and special techniques to help these students succeed. Our vision is to create a k school that is highly regarded for its academic excellence, and for its contribution in actively serving and improving the community in which it operates.
A vision is more than broad, flowery statements. The vision helps people understand how you hope others will view you, and describes some of your highest priorities.
A mission or vision statement is the shared vision of people in a school about their ultimate purpose. In other words, it is a collective commitment of the school community.