Perception

Question 1

What is Perception?

Answer 1

A complex set of processes by which we organise, recognise and make sense of the sensations we receive form environmental stimuli.

Question 2

What are three key features of perception?

Answer 2

Changes based on added information.
Perception is an active process, similar to reasoning or problem solving.
Occurs in conjunction with actions.

Question 3

Which two types of information re used by the perceptual system?

Answer 3

Environmental energy stimulating the receptors.
Knowledge and expectation the observer brings to the situation.

Question 4

Why are perpetual objects NOT reflections?

Answer 4

We have no capacity to perceive the world as it actually is, therefore, a lot of how we perceive is culture dependent e.g. some languages only have two colour categories while others have 15.
The way we see a cat is as a result of a neural representations hat we have of a cat. This is why we see so many “black cats” when there are actually very few as most of them either have tabby stripes of are actually dark brown.

Question 5

Is human perception special?

Answer 5

No. Unlike humans, most other mammals, many birds, and insects, and fish can see ultraviolet light + infrared, snakes can even see temperature. There have been many attempts to replicate “bird vision” or “dolphin sounds” but we are unable to completely replicate these.

Question 6

What are Blaschko lines?

Answer 6

Unique human marking in our skin lines that are very similar to zebra stripes.

Question 7

Why can pets maybe see our stripes while we cannot?

Answer 7

Our stripes are invisible to our visual system however, we have occasionally been able to see the under extremely strong UV lights which may suggest that animals that can see ultraviolet are able to see our stripes.

Question 8

How do we know what other species can see?

Answer 8

It is an estimation based on the receptors we find, looking at the retina of a reptile we can create an estimation of what we think they will see and then carry out research to investigate the estimation.

Question 9

Why can we not replicate human perception of computers? (3)

Answer 9

Inverse Projection Problem.
Objects can be hidden or blurred.
Viewpoint invariance.

Question 10

What is the inverse projection problem?

Answer 10

We can perceive objects as they are due to our inverse projection whereas computers can only perceive in 2 dimensions.

Question 11

Why is it an issue for computers if objects are hidden or blurred but not for humans?

Answer 11

Computers see via edges - the contrast between neighbouring pixels - they cannot interpolate missing parts, if an image is not sharp they cannot compute its edges. Whereas, even if images are blurred or hidden, our knowledge of objects allows us to “fill in the gas” and still interpret the image.

Question 12

What is viewpoint invariance?

Answer 12

Objects look different from different viewpoints, machines do not have depth perceptions whereas humans do which allows us to perceive different objects from different viewpoints.

Question 13

What are the two main approaches to understanding perception?

Answer 13

Direct Perception Theories.
Constructive Perception Theories.

Question 14

What are the key features of direct perception theories? (3)

Answer 14

Bottom-up processing.
Perception comes from the stimuli in the environment.
Parts are identifies and put together, and then recognition occurs.

Question 15

What re the key feature of constructive perception theories? (3)

Answer 15

Top-down processing.
Processing originates in the brain, “top” of the perceptual system.
People actively construct perceptions using information based on expectations.

Question 16

Is perception of pain a top-down or bottom-up process?

Answer 16

Bottom-up because pain occurs when the receptors in the skin are stimulated. Therefore, it depends on stimulation of the receptors.

Question 17

How can pain be a top-down process?

Answer 17

If we are anticipating pain we can alter the extent to which we feel it therefore creating a top-down process.

Question 18

Is language a top-down or bottom-up process?

Answer 18

Top-down because we use both speech segmentation and transitional probabilities to better understand language.

Question 19

What is speech segmentation?

Answer 19

The ability to tell when one word ends and the another begins.

Question 20

What are transitional probabilities?

Answer 20

The knowledge of which sound will likely follow another in a word.

Question 21

What is an object?

Answer 21

Any entity that is close and can be moving, on term of perception a person walking away is a moving object.

Question 22

What is Helmholtz’s Unconscious Inference?

Answer 22

Some perceptions are the results of unconscious assumptions we make about the environment. We infer much of what we know about the world.

Question 23

What is the Likelihood Principle?

Answer 23

We perceive the world in the way that is “most likely” based on our past experiences.

Question 24

How does fear affect eye-witness testimonies?

Answer 24

The more scared a person is, the more likely they are to stay there was a weapon even if there wasn’t.

Question 25

What do the Gestalt Principles say?

Answer 25

The mind groups patterns according to intrinsic laws of perceptual organisation based on knowledge about the world.

Question 26

What are the four main Gestalt Principles?

Answer 26

Figure Ground Principle.
Principle of Good Continuation.
Law of Pragnanz.
Principle of Similarity.

Question 27

What does the Figure Ground Principle state?

Answer 27

There needs to be distinction between an object and its background.

Question 28

What does the Principle of Good Continuation state?

Answer 28

Lines tend to be seen as following the smoothest path, good continuation help use perceive the rope as a single strand.

Question 29

What does the Law of Pragnanz state?

Answer 29

Principle of simplicity or good figure; every stimulus pattern is seen so the resulting structure is as simple as possible. If there is a dark image with a triangle, a circle and a square all overlapping we will perceive it as the three separate simple shapes rather than one more complex shape.

Question 30

What does the Law of Pragnanz state?

Answer 30

Principle of simplicity or good figure; every stimulus pattern is seen so the resulting structure is as simple as possible. If there is a dark image with a triangle, a circle and a square all overlapping we will perceive it as the three separate simple shapes rather than one more complex shape.

Question 31

What does the Principle of Similarity state?

Answer 31

Similar things appear grouped together, if there is an image in which there are three rows of shapes and each row is a different colour, the rows will appear grouped separately to the others.

Question 32

What are the four key points of the Gestalt Principles of Perceptual Organisation?

Answer 32

Perception is determined by specific organising principles, not just lightwaves activation the retina.
Perceptual organisation is a feature of the stimulus (bottom up).
Role of experience is minor compared tot eh intrinsic, “built in” principles.
Experience can influence perception but is not the key driver.

Question 33

What is the modern view on perception?

Answer 33

Perception is influenced by common physical properties of the environment. This means it is based on experience, not innate/intrinsic.

Question 34

What is the Oblique Effect?

Answer 34

We perceive verticals and horizontals more easily than other orientations.

Question 35

What is the Light-from-above assumption?

Answer 35

We assume light comes from above because this is common in our environment e.g. the photo with the “upside down peas” when in reality we just perceive them as upside down because of where the light is coming from. We also perceive shadows as specific information about depth and distance.

Question 36

What does regularities of the environment refer to?

Answer 36

The context in which we see an object will change our interpretation of what the object is. E.g. a “life is short, lick the bowl” sign makes a lot of sense in the kitchen but not in the bathroom.

Question 37

What are scene schema?

Answer 37

The knowledge of what a given scene ordinarily contains, cultural differences can also influence perception.

Question 38

What is Bayesian Inference?

Answer 38

One’s estimate of the probability of a given outcome is influenced by two factors:
- The prior probability.
- The likelihood of a given outcome.

Question 39

What three conceptions of object perception are top-down processing and why?

Answer 39

Unconscious inference.
Environmental regularities.
Bayesian inference.
(use of knowledge in perception)

Question 40

What conception of object perception is bottom-up processing and why?

Answer 40

Gestalt Principles.
(built in perceptual principles).

Question 41

What does experience-dependent plasticity mean?

Answer 41

Mechanism through which the structure of the brain is changed by experience, this means that neurons become tuned to respond best to what we commonly experience.

Question 42

How does movement facilitate perception?

Answer 42

Moving add complexity to perception to if we stood still however, moving around a stimulus offers us more views to create an accurate perception.

Question 43

How does the interaction of perception and action help us?

Answer 43

We are constantly interpreting the world in flow which means we can perceive and act really quickly.

Question 44

How do perception and action interact in the brain?

Answer 44

The sensory and motor cortexes have a specific rhythm that no other neurones use via which they communicate (μ rhythm).

Question 45

What is the ventral & dorsal visual pathway?

Answer 45

The dorsal pathway of perception connects input from the visual cortex to the parietal lobe which means that we can connect vision to feelings e.g. seeing a dangerous animal coming towards you causes you to feel tense and scared.

Question 46

Example of stroke damage to ventral & dorsal visual pathway?

Answer 46

A patient had a stroke causing damage to the ventral “what” stream, when they were asked to orient a credit card to insert it into an ATM they can’t process the direction of the cards but they can put it in the slot because they can process the “where” but not the “what”.