1. Sensation and Perception - eye.ppt © 2001 Dr. Laura Snodgrass, Ph.D.1 Eye Cornea - 2/3 focus power Iris and pupil - trade off between “depth-of-field” and light Lens - works with ciliary muscles and zonular fibers to do accommodation Sclera - outer coating Retina - 5 layers of cells Fovea - where you are looking Blind spot - where optic nerve leaves the eye

2. Sensation and Perception - eye.ppt © 2001 Dr. Laura Snodgrass, Ph.D.2 Focusing The Image Visual angle –the same size object will produce different images sizes depending on its distance. Closer objects produce larger retinal images.

3. Sensation and Perception - eye.ppt © 2001 Dr. Laura Snodgrass, Ph.D.3 Focusing the image The cornea and lens bend the light rays so the image on the retina is upside-down and left-right reversed The lens works with the ciliary muscles and zonular fibers to accommodate (focus) for different distances

4. Sensation and Perception - eye.ppt © 2001 Dr. Laura Snodgrass, Ph.D.4 Accommodation Far object –need a flat lens - relax ciliary muscle to pull zonular fibers tight across lens Near object –need a plump lens - constrict ciliary muscles to loosen zonular fibers so lens can plump out

5. Sensation and Perception - eye.ppt © 2001 Dr. Laura Snodgrass, Ph.D.5 Five Layers Of Cells In The Retina Receptors - rods and cones Horizontal and Amacrine cells - lateral inhibition Bipolar and Ganglion cells - afferent = sending signal towards brain Optic nerve = axons of the ganglion cells