VISUAL PERCEPTIONArea of Study 2

Visual Sensation Visual Perception

-Physiological- Visual sensation is the same for everyone-It is our physiological make up of the eye and the way it functions

-Reception-Transduction-Transmission

- Psychological and physiological -Visual perception differs as everyone perceives and interprets things differently-When studying Visual Perception it is difficult to say where one starts and the other begins so we see it as an interrelated process.

-Selection (also occurs in sensation through reception process)-Organisation-Interpretation

Absolute Threshold Differential Threshold

- is the minimum amount of energy needed to detect a stimulus under ideal conditions fifty percent of the time.

- For example, the absolute threshold for the visual sensory system enables us to see a candle flame at 50 kilometres .

-is the smallest difference in the amount of a given stimulus that a specific, sense can detect.

-For example, the differential threshold enables us to perceive difference in two separate stimuli (i.e. When we go to an optometrist). When a change can no longer be detected it has exceeded our threshold.

Process Description

Reception Reception or capture of visual stimuli in the retinas of the eye by sensory neurons called photoreceptors.

Transduction Transduction or conversion of electromagnetic energy (light energy) into electrochemical energy (or neural impulses) by photoreceptors

Transmission Transmission of neural impulses, via one neuron to another, through the optic nerve to the brain.

Selection Selection of features of a stimulus by specialised neurons in the visual cortex called feature detectors.

Organisation Organisation of the stimulus features into patterns or groupings to closely represent the original stimulus in a meaningful way.

Interpretation Interpretation or understanding of what the stimulus represents in the external world.

Sue Requires Two Things, whereas Paul Selects One Item.

Sensation involves Reception, Transduction and Transmission,

While Perception involves Selection, Organisation and Interpretation of information.

Gestalt Principles

Figure-Ground

Closure

Similarity

Proximity

Constancies

Size Constancy

Shape Constancy

Orientation Constancy

Brightness Constancy

Monocular Depth Cues Binocular Depth Cues

Accommodation (A) Retinal Disparity (R)

PICTORIAL CUES: Convergence (C)

Texture Gradient (T)

Height in the visual field (H)

Relative Size (R)

Interposition (I)

Linear Perspective (L)

CAR THRIL

Visual Illusion Explanation

Muller-Lyer Perceptual compromise Hypothesis (Ross Day)- Two or more visual cues conflict with each other when interpreting visual information.

Ames-Room Apparent distance hypothesis-When two retinal images are the same size, but one that appears to be a greater distance then the one that appears to be further will be interpreted as larger.-Size constancy fails

PERCEPTUAL SET (EXPECTANCY):

Context Past Experience

-Context refers to the setting in which a perceived stimulus occurs.

- In other words, context refers to the physical or circumstantial surrounds in which the observed event or object sits.

-Past experience can affect visual perception, especially if the experience holds significant personal meaning.

-The subjectivity of the experiences may cause particular stimuli to be interpreted differently by different people.

Perceptual set is a predisposition or expectancy to perceive stimuli in a specific way.

Closure

Proximity

Similarity

Figure-Ground

Closure

Closure

Figure-Ground

Retinal Disparity

Accommodation

Convergence

Linear Perspective

Relative Size Height in the Visual Field

Interposition

Texture Gradient

Orientation Constancy

Brightness Constancy

Shape Constancy

Size Constancy

Which of the following structures is first to be involved in the process of selection in visual perception?

a) The photo receptor cells

b) The lens

c) The neurons in the visual cortex

d) The optic nerve

Anna has chronic sinusitis (blockage of the canals that drain into the nostrils) and headaches. Her plastic surgeon decided that instead of drilling a hole in the bridge of her nose, her will push a tube down the corner of her eye through the ciliary muscles and clear the nasal passages. For the next week, Anna finds that her vision is blurry. Her vision is blurry because:

a) The fluid behind her eyes and nose has now been drained

b) The eye muscles are disturbed and so images at the fovea are no longer clear

c) She can no longer use retinal disparity as a depth cue

d) She has lost some aqueous humor and the cornea cannot function correctly

Many people perceive the black diamonds in this picture as forming a cube. The Gestalt principle that is most important to achieve this perception is:

a) Closure

b) Proximity

c) Simplicity

d) Reversibility figure

 

The slanting lines are used as a depth cue. The slanting lines are an example of:

a) Interpositions

b) Height in the visual field

c) Relative size

d) Linear perspective

The process of transduction occurs ina) The photoreceptor cellsb) The optic nervec) The neurons in the visual cortexd) The lens

Which of the following is a primary monocular depth cue?

a) Interpositionsb) Texture gradientc) Accommodationd) Convergence

Benita plans to carry out research into different eye problems and their effects on depth perception. Benita must

A. match the names of her participants with their results in her report.

B. inform participants of their obligation to disclose all relevant information.

C. inform participants that they are not allowed to withdraw from the research.

D. ensure that her participant’s personal details are not exposed.

Philip is conducting research on children who have a particular eye disorder. His theory is that children with this eye disorder are unable to perceive the Müller-Lyer illusion. He conducts a study with two groups: one group of children with the eye disorder and a second group of children without the eye disorder. The two groups are matched on age, sex and intelligence.

In this research design, the group of children with the eye disorder is the ___________ group and the group of children without the eye disorder is the __________ group.

A. experimental; control

B. control; experimental

C. random; stratified

D. stratified; random

SHORT ANSWER QUESTIONS

Allan lives near the You Yangs and Barbara lives in Baccas Marsh. Both of them are psychology students who live in houses high up on a hill. There houses are nearly 25 kilometres apart. They ring each other and agree to turn all the house lights off. Over the next 10 minutes Alan lights a candle 10 times. Barbara notices a change 6 times.

What is an absolute threshold?

Identify a way they could measure a JND?

SHORT ANSWER QUESTIONS Explain the processes of organisation and interpretation?

Trisha is researching the effect of context on visual perception. She intends to show participants an ambiguous image that can be interpreted as waves in the ocean or a bird’s face. Trisha selected participants randomly from her target population and then randomly allocated them to two experimental groups. For each group, she plans to use context to create a different perceptual set; one of land and water, the other of animals.

a. Give an example that Trisha could use that will help participants create a perceptual set in relation to this ambiguous figure.

b. Outline one strength and one limitation of random sampling.

James sustains an injury to his left eye, and has to wear an eye patch for several weeks.

a. Name a depth perception cue that James would be unable to use.

b. b. Name a non-pictorial depth cue that James would be able to use and explain how this cue would assist him to perceive depth.

SHORT ANSWER QUESTIONS

a. Clearly state how the Ames room is constructed in terms of its shape and the position of the peephole to create an illusion.

b. Bernadette has never heard of the Ames room illusion while Kane is familiar with the Ames room illusion and has an understanding of why this illusion is thought to exist. Both look through the peephole and watch a person walk from one corner to the other.

What would you expect Bernadette and Kane to perceive?

Bernadette:

Kane:

SHORT ANSWER QUESTIONS