Lecture 1 - Problems with Perception

Question 1

What is the purpose of perception?

Answer 1

To collect information and make sense of the world.

Question 2

FINISH the SENTENCE: Visual and auditory _ creates _ to form _ perceptions.

Answer 2

Noise, distractions, accurate

Question 3

What happens to sensory signals when the environment is noisy or crowded?

Answer 3

It’s challenging to encode and process sensory information. Signals are drowned out.

Question 4

TRUE or FALSE: Sensory systems are unlimited and cannot become overloaded.

Answer 4

FALSE: Sensory systems are limited and can become overloaded.

Question 5

How do sensory systems work?

Answer 5

Sensory systems act as filters for environmental information or input.

Question 6

Give an example of a sensory system. Can we process more than what the system lets in?

Answer 6

Wavelengths of light are filtered by three types of cones (red, blue, green), allowing colour vision.

We can’t process more than the information we have been given - only what the filter lets in. As such, we do not process all the visual spectrum simultaneously.

Question 7

Is this filtering useful or detrimental?

Answer 7

Useful. Filtering allows us to organise only the relevant and necessary sensory information.

Question 8

Which two lobes primarily process perception, and what can disrupt the flow of information?

Answer 8

The occipital and temporal lobes. Information entering these areas can be disrupted by conditions of the environment.

Question 9

FINISH THE SENTENCE: _ _ information can guide our perceptions through top-down informational processing.

Perception is a mix of both top-down and _.

Answer 9

Already known, bottom-up

Question 10

TRUE or FALSE: Seeing is a faithful record. Our eyes work like a camera. The outside world is captured like on film. As such, the visual system is infallible, and we cannot be deceived.

Answer 10

FALSE: Seeing is not a faithful record. Our eyes do not work like cameras.

The eye and the brain must cooperate - we have to integrate already known knowledge and what we see to form images. As such, the visual system is vulnerable to error - this causes illusions, seeing elements that are not truly there.

Question 11

How do we visually construct images?

Answer 11

To create a full image, we construct individual elements present in the environment and integrate them together, rather than capturing single components.

Question 12

Give an example of how we construct images or visual records in the visual system. (5)

Answer 12

An image may first be perceived through its colour - encoded by retinal cones - and contrasts - determined by different spatial frequencies.

The image continues to be formed through the primary visual cortex and creates mental representations (i.e., certain signals from simple cells).

The full image is formed through higher order mechanisms, integrating all sensory information.

Question 13

Is vision a passive process and rich in detail? How do we know an image is incorrect?

Answer 13

Vision is an active process and is lacking in detail.

We only notice if something is wrong about an image if we direct ourselves to its details.

Question 14

Do we focus on all of the image or only on details? (3)

Answer 14

We focus only on the important details. Our visual system samples on a ‘need-to-see’ basis. Eye movements are goal directed.

Question 15

Is imageless thought a myth or fact?

Answer 15

Imageless thought is a myth, although conditions such as aphantasia exist. This is where the individual cannot visualise mental imagery.

Under normal circumstances, we can recreate scenes and imagine different scenarios through mental imagery.

We use the same areas of the brain in creating mental imagery as visual perception.

Question 16

Do people with aphantasia or colour blindness realise they have these conditions? Why or why not?

Answer 16

They often do not. This is because their sensory systems have found ways to substitute processing in the absence of typical mechanisms.

Question 17

TRUE or FALSE: The brain processes all sensory information simultaneously and in the same area.

Answer 17

FALSE. The brain separates and organises information into different sensory categories. This includes sound, colours, depth, etc.

Question 18

What is the difference between lower level processes and higher level processes?

What can the brain be considered in considering this?

Answer 18

Lower level processes form images and perceptions, identifying individual elements and encoding them.

Higher level processes integrate this sensory information to construct the sensory experience.

The brain is a map that locates where different elements are processed/categorised/integrated.

Question 19

Where does the visual system start?

Answer 19

The visual system starts at the eyes and the retina.

Question 20

How many types of ganglion cells are there in the eye and what do they process?

Answer 20

There are 30 types of ganglion cells. These mainly process space and colour.

Question 21

What are the three main types of ganglion cells? What does their size indicate?

Answer 21

The three main types of ganglion cells (in order of smallest to largest) are midget, bi-stratified, and parasol.

The larger the cell, the more visual information that can be processed.

Question 22

The Lateral Geniculate Nucleus (LGN) has 6 layers. Describe the three sizes of these layers and where the LGN is located.

Answer 22

The 6 layers of the LGN are magnocellular, parvocellular, and koniocellular in order of size (largest to smallest).

Four layers receive parvocellular input. Two layers receive magnocellular input. The LGN is in the thalamus.

Question 23

The Lateral Geniculate Nucleus sends input towards what system?

Answer 23

The LGN sends information to the Primary Visual Cortex - otherwise known as the Straite Cortex.

Question 24

The primary visual cortex is separated into six layers. Each layer has different cells, and each functions differently.

What is the main function of V1 - the first layer of the primary visual cortex - and how does this section organise information?

Answer 24

V1 organises information through sorting colour contrast, achromatic contrast, ocular dominance, and orientation columns.

Question 25

What are the main functions of the primary visual cortex’s other stripes (V1 to V5)?

Answer 25

V1, V2, V3, V4, and V5 are selective for orientation, binocular disparity, and motion direction.

Question 26

The stripes are further divided into two main pathways. What are these called, what are their functions, and what size are the cells within them?

Answer 26

The two pathways of the primary visual cortex are:

The Ventral Pathway. This processes information relating to what is the object. This pathway has parvocellular, small cells which select for form and colour. It is also called the perception pathway.

The Dorsal Pathway. This processes information relating to where is the object. This pathway has magnocellular, large cells which select for motion and depth. It is also called the action pathway.

Question 27

How does the visual cortex improve efficiency in its organisation?

Answer 27

Areas closer together tend to process and select for the same elements. This shortens the flow of information and improves efficiency.

Question 28

YES or NO. Does visual information from the environment cross between areas of the visual cortex?

Answer 28

NO. Information from the environment remains segregated and independent throughout visual processing.

Question 29

Describe Ungerleider and Mishkin’s (1983) study. What did they do?

Answer 29

Ungerleider and Mishkin (1983) lesioned areas in the ventral and dorsal pathways in monkeys.

Lesion in the ventral, ‘what’ pathway: Could no longer discriminate between objects.

Lesion in the dorsal, ‘where’ pathway: Could no longer complete the landmark discrimination task.

Question 30

Which study presented the case of DF who had visual form agnosia?

Answer 30

Goodale and Milner (1992).

Question 31

Goodale and Milner (1992) provided evidence for the dissociation between perception and action. How did they do this?

Answer 31

The ventral (perception) and dorsal (action) pathways were assessed through hand orientation tasks. DF had to match their hand’s orientation to post a letter.

DF, with visual form agnosia, could not properly orient their hand to different letterbox openings. Their movement was also extremely varied (perception). Yet, when asked to post a letter, they did so similarly to controls (action).

Question 32

Describe the Ponzo Illusion. Which study investigated this using normal samples, and what did they find?

Answer 32

The Ponzo illusion involves two lines of the same length, but these change in lengths in different contexts. Line 1, nearer to the subject, is often perceived as shorter than Line 2, further away. They are still the same length.

Ganel et al. (2008) used this to dissociate between perception and action. Participants could accurately grasp both lines (action), but would incorrectly say that line 2 was longer (perception).

As this was in normal samples, the study has an advantage in external validity in comparison to primate or case studies.

Question 33

TRUE or FALSE. Perceptions are active and inform us only about important aspects of the environment. We perceive what is important at any given time.

Answer 33

TRUE. Only when we attend to details do we know that an image is wrong. Vision is not a faithful record and is lacking in detail.

Question 34

FILL IN THE GAPS. Representations of objects are _, in a _ way, by _ sub-systems. We do not copy images like a camera to see them.

Answer 34

Constructed, Layered, Specialised

Question 35

YES or NO. Can the visual system process far away objects as well as near objects?

Answer 35

YES. The visual system is special as it allows for depth perception. It conveys messages about distant objects and objects that are directly in front.

Question 36

How does perception aid survival? What lies at the core of perception?

Answer 36

Perceptions enable us to make decisions and actions. This is helpful in spotting predators, identifying edible/toxic food, and potential mates.

Perception is all about decision making; deciding what is important and relevant to us.