Recap – lesson 1

What is perception?Perception: The process which we give meaning to sensory information, resulting in our own interpretation.

What is Visual perception?Visual perception is the ability to interpret information and surroundings

via our eyes.

For example, when you organised the black and white patches into the shape of a cow

Visual Sensation is the initial process of detecting and decoding environmental information

For example: When you look at the first picture of the cow, your eyes transmit information to your brain about which parts are white and which parts are black.

The process of Sensationand Perception

Eye structure and functions

• Pupil:The opening in the centre of the iris. The size of the pupil determines the amount of light that enters the eye.

• LensTransparent flexible structure in the eye that focuses light on the retina by changing shape

• IrisThe coloured part of the eye. The muscles of the iris change the size of the pupil

• Cornea• The front covering of the eye that covers the iris and pupil

• RetinaA multi-layered sensory tissue that lines the back of the eye.  It contains photoreceptors that capture light rays and convert them into electrical impulses. These impulses travel along the optic nerve to the brain where they are turned into images. 

Vision process• Looking at your diagram, what order do you

think the vision process occurs in? Label in pencil 1-5.

1.Cornea2.Lens3.Pupil4.iris5.Retina

On your poster, draw arrows or write the order of the vision process.

Today’s objectives:

•Characteristics of the visual perception system

Visual System Characteristics - RTTOI• Reception• Transduction• Transmission• Organisation and Interpretation

Activity: Create a sentence whereby the first letter of each word is the visual system process – RTTOI.

For example, Rowan Tried To Overcome his Idiosyncrasies

Reception

Reception: is the process by which the structures of the eye capture an image of a visual stimulus and focus it on the photoreceptors in the retina.

There are two types of photoreceptors:Cones: Photoreceptor that responds to high levels of light –

responsible for detecting colour vision and fine details.

To remember : you eat ice-cream (cone included) during the day when its light.

Rods: Photoreceptor that responds to very low levels of light – responsible for night vision.

To remember: you go fishing (with your rod) at night when it is dark.

Reception

Transduction

•Transduction: the process by which photoreceptors in the retina change electromagnetic energy (light) into electrical impulses (signals) which can travel along the optic nerve to the brain.

•More simply, conversion of the information into a form that can be processed

Reception + Transduction

TransmissionThe process of transferring or moving info from one location to another. (I.e. from receptor cells

to the brain)

•The optic nerve carries the visual information from the retina to the visual cortex which is located at the back of the brain + specialises in receiving and processing visual information.

Transmission

Organisation and Interpretation• Organisationinvolves assembling or arranging the features of avisual image in a meaningful way.

For example, we perceive a ‘house’ rather than ‘doors, windows, walls, roof, chimney

• Interpretation is the process of assigning (or ‘giving’) meaning to visual

information so that we can understand what we are looking at.

• For example, we know that an aeroplane doesn’t get physically smaller as it takes off from the runway and flies into the sky even though it appears to shrink.

Organisation + Interpretation

•Complete Learning Activity 3.5 – page 100

VISUAL PERCEPTION PRINCIPLESVisual perception principles can be

classified intothree broad categories:•Gestalt principles•Depth principles•Perceptual constancies

Gestalt PrinciplesGestalt = “organised whole”

Gestalt principles refer to the ways in which we organise the features of a visual scene by grouping them to perceive a whole, complete form.

4 types of gestalt principles•Figure-ground organisation•Closure•Similarity•proximity

The eye differentiates an object from its surrounding area.

Figure-Ground

A form, silhouette, or shape is naturally perceived as figure (object), while the surrounding area is perceived as ground (background).

Balancing figure and ground can make the perceived image more clear.

What is the ‘figure’? What is the ‘ground’

Complete your own definition of figure-ground

Closure

Occurs when an object is incomplete or a space is not completely enclosed.

It is the tendency to ‘close’ or ignore the gaps in stimuli, and perceive it as complete

We see three black circles covered by a white triangle, even through it could just as easily be three incomplete circles joined together.

What do you see?

Our minds react to patterns that are familiar, even though we often receive incomplete information

Write a definition for

closure

SimilarityThe principle of similarity states that things which share visual

characteristics such as shape, size, color, texture, value or orientation will be seen as belonging together.

It is the tendency to perceive that stimuli or parts of a stimuli that have similar features as one part of a whole

We group together the similar objects (dark blue circles) to perceive a number five

What do you see?

Write a definition for similarity

Proximity occurs when elements are placed close together. They tend to be perceived as a group.

Proximity

The nine squares above are placed without proximity. They are perceived as separate shapes.

When the squares are given close proximity, unity occurs. While they continue to be separate shapes, they are now perceived as one group.

How do you see these grouped?

Because of proximity, we see two groups, each containing two lines of circles, rather than four separate lines of circles.

Write a definition for

proximity

MINI TEST

What are these pictures examples of?

Similarity

Figure-ground

Proximity

Closure

•Complete