ART TECHNOLOGIES 1201 LESSON 2

OUTCOMES In this lesson, you will learn… To identify the structure of the human eye How the eye “sees” To describe some of the conditions associated with vision problems How some technology can assist human vision

THE HUMAN EYE Understanding human visual perception begins with the eye. If you know about the different parts that make up the eye, understand the working relationship between the eye and the brain, and can recognize some of the basic strengths and weaknesses of the eye, then you’re on your way to knowing how human vision operates. You will also be better able to make key choices when planning to create a piece of art!!

The adult human eye is about 2.5cm in diameter. Our eyes sit in their own cavities in the skull (eye sockets) which help to protect them from injury. The front of the eye has a slight bulge. This is the cornea. If the cornea tissue is healthy, it is clear, allowing light to pass through the pupil. The pupil is the opening (which changes based on the amount and strength of light available) in the coloured muscle at the front of each eye. The pupil appears to be black, but it is actually a hole formed by the iris (the coloured part) so it doesn’t have a colour. Light travels through the vitreous humour (clear jelly filling). It hits the retina, which passes the sensation along to the optic nerve to travel to the brain.

Have you even gotten a photo taken, but in the photo you had red-eye? This happens because often, the flash of the camera “surprises” your eye so the iris doesn’t have a chance to contract to narrow the pupil opening. The light travels to the retina, with all its blood vessels, which show up red when recorded on the image stored in the camera. So, when you see “red eye” on a photo, you’re actually seeing the inside of the eyeball!! Newer cameras have “red-eye reduction”, in which the flash goes off twice before the photo is captured, so that the eye is “warned”.

Our eyelids also help control the amount of light that enters the eye (by closing our eyelids, sqinting, or staring intently. They also help to keep our eyes moist with tears.

Each eyeball has a single, flexible, transparent lens to focus light from an image onto photoreceptors onto the retina. The light sensitive photoreceptor cells that live there consist of two types: Rods (which see light, particularly at low levels, like at night. They can only project black and white. This is why you don’t see very much colour when there is very little light around you.) ** Cones (which are used for colour vision… think C for “colour” and “cones”)

Once light enters the eye, it is focused by the iris and lens onto the photoreceptors in the retina, which results in an UPSIDE DOWN image made of millions of dots. The fovea is the spot in the retinal with the sharpest focus. All of the light sensing cells send a rapid signal to the brain via the optic nerve. The brain receives the signals from both eyes and interprets them into one continuous image, RIGHT-SIDE-UP.

COMMON VISION PROBLEMS Damage to the eye can result in blindness or a partial loss of sight. (So wear sunglasses and don’t look directly into bright light) People who see well close-up but who have difficulty seeing objects at a distance are near-sighted. Those people who see objects well at a distance but not close up are far-sighted. (These conditions can be corrected with glasses, contact lenses, or laser surgery) Colour Blindness is a hereditary condition – passed from parents to their children – resulting in an inability to distinguish between some colours. An inability to distinguish between green and red is the most common. Males are more likely than females to have colour blindness. (Men who are colour blind pass the gene onto their daughters, making it likely that their daughters will have a colour blind son…)

People who can’t see well in low light levels are said to have night blindness (believed to be caused by a vitamin deficiency). Many artist’s work from the past have been explained as showing the effects of eye problems. Astigmatisms provoked elogated figures. Cararacts (which blur vision) was shown in art work by “auras” around light sources (i.e. a glow of light around the moon)

TECHNOLOGICAL EYES People have created technological “eyes” to perform very specific jobs, enhancing our ability to “see” in much better and different ways that our eyes could on their own. Examples: Satellites relay pictures of our planet and of space Remote controlled devices with stereoscopic cameras (i.e. The Pathfinder vehicle which landed on Mars) send us 3D images, making it seem like you could be there Telescopes and microscopes assist us in seeing objects far away and objects too small to see Here is an image from NASA’s Hubble telescope of a place a few hundred million ‘light years’ away

LESSON 2 ASSIGNMENT Part 1: Visit the Art Gallery of Newfoundland and Labrador online. Look through some of the collections/images. Respond to the question. Part 2: Draw a picture using some aspect of Newfoundland and/or Labrador as your subject/theme. It might involve something from our history, a famous location or person, etc. Use pencils and/or coloured pencils to do the drawing. Part 3: A collage is an image created from other assorted images. Using photographs, magazines, advertisements, web-images, etc. create a collage on one of the given themes. (Example on the next slide)