Topic A

keywords

optic nerve - transmits visual information from the retina to the brain

optic chiasma - point information crosses over

rods - detects light

cones - detect different colour

retina - very sensitive to light

nerve impulse - an electric impulse to the brain

• light is reflexed off an object entres the eye and makes an image on the retina (the layer at the back of the eye),which the retina is covered with thousands of light - detecting cells called rod and cones
• the retina which is very sensitive to light, sends nerve impuse to the brian. The nerve impulse travels along the optic nerve
• information from frome each eye travle along the optic nerve to each side of the brian
• information from the left and righ eye crosses over at a point called the optic chiasma

vistion vs perception

vision: our eye works by detecting rays of lights that are refleced or emitted by object. This is a biological process that happenedin our eyes.

perception: happens in our brain, it is a psychological process during which our brain makes sense of the visual image. 

 The visual cortex

the visual cortex interpered information from the optic nerve.

Topic A     Theory 1

how do we see size and depth?

light reflects off an object and into our eye, lens then to the retina where the rods and cones which help me see colour and brightness.

key words

Depth cues - The visual clues that we use to understand depth and distance.

Monocular depth cue - The information about dis tance that cones from one eye, such as relative size, texture gradient.

Bhinocular depth cues - in formation about distance that needs two eyes, e.g steropsis.

Steropsis - this is a cue to depth that the brain works out by comparing the view from the left and right eye. the bigger te difference between them, the closer the objcet you are looking at.

Size contancy - we perceive on object as the same size even when it's distance from us change.

Distance: things e sclaed up to make then seem bigger on the retina.

Nearby: things are scaled down to make them seem smaller on the retina.

Topic A       thoery 2

• figure ground
• similarity
• continuity
• proximity
• closure

Gestalt Laws

Gestalt say when we see we catergarise things

Figure ground: It the main image, more complex more symmetrical and small.

Similarities: When a view has colours and one colour stands out to make an objest or shape.

Coninuity: We see lines curves, shapes and objects meeting up and continuing as if ther were the same object some times we read a book and the gaps between seem lines swiggely lines.

Proximity: we see objects as close together related- in blocks or groups.

Closure: we perceive ojects as a whole even though they are not completed, we make the lines into a complete edge and there for percieve the full shape.

Topic A            Theory 3

monocular and bonocular depth cues

Binocular depth cues:steropsis

This is a cue to depth that the brain works out by comparing the view from the left and right eye. the bigger the different between them, the closer the object your looing at.

monocular depth cue

relative size - smaller object are perceived as futher away than larger ones

texture gradient - close up textured surface is very detailed, from futher away the texture is less clear

height in the plane -  closer the object is to the hoirzon are futher away, those which are higher up from the hoirzon are closer

superimposition - the thing you can see must be nearer then the partly hidden object behind

linear perspective - lines which are paralle appear to meet together in the distance

Topic A    illusions

Visual illuion - a comflict between reailty and what we perceive

Fiction - occurs when you perceive a shape that is not there. sometime we perceive edges and belive that a shape exists when there is no actual boundary

Illusory contour - a boundary (edge) thats is perceived in a figure but is not present in the stimulus.

Colour after effect - an illusion caused by focusing on a coloured stimulus and perceiving opposite colour immediately afterwards

Motion after effect - an illusion caused by paying attention to movement in one direction immediately afterwards

Ambiguous figure -  a stilulus with two possible interpretaion, in which it is possible to perceive only one of the alternative at anytime

Distortion illiusion - where our perception in deceived by some aspect of the stimulus. this can affect the shape of size of an object.