Chapter 3- Perception

Question 1

Perception

Answer 1

Organization, identification and meaningful interpretations
of sensory information, and our experiences resulting from stimulation of the senses.

Question 2

Characteristics of perception (5)

Answer 2

1. Perceptions can change based on added information
2. Perception can involve problem solving. Sometimes we are able to determine what something is based on having seen it previously in another context.
3. Perception can be based on a perceptual rule- when objects overlap, the one underneath usually continues behind the one on top, for example.
4. Perception occurs in conjunction with action- we must perceive a coffee cup to grab it. Perception is central to our ability to organize the actions that occur as we interact with the environment.
5. Perception is the gateway to all other cognitions- it is necessary for memory, answering exam questions, communicating with others, etc

Question 3

Inverse projection problem

Answer 3

The stimulus on receptors is ambiguous. The perceptual system starts with the image on the retina, and its goal is to determine what object created the image. This task is called the inverse projection problem.
It involves starting with the retinal image and extending rays out from the eye. A particular image on the retina can be created by many different objects in the environment.

Question 4

Viewpoint invariance

Answer 4

People’s ability to recognize an object even when it’s seen from different viewpoints. Objects are often viewed from different angles, so their viewpoints are always changing.

Question 5

Bottom up processing

Answer 5

The sequence of events from the eye to the brain. It starts at the “bottom” of the system, where environmental stimuli reach the receptors.

Question 6

Top down processing

Answer 6

The knowledge we have of the environment. Perception also involves the expectations a person brings to the situation. This allows us to quickly identify objects and scenes, and to go beyond the identification of objects to determine the story behind a scene.

Question 7

Why are we still able to perceive blurry objects?

Answer 7

Blurry pictures example- the pictures all look similar, but we are still able to perceive what’s going on in them. Due to their context and orientation, we can use our knowledge of what kinds of objects are usually found in different scenes to perceive them.

Question 8

Speech segmentation

Answer 8

The ability to tell when one word in a conversation ends and the next one begins. An individual’s experience with language influences their perception- someone who speaks English receives the same stimuli while listening to Spanish speakers as someone who speaks Spanish. However, to an English speaker, Spanish will sound mostly continuous without breaks between words. Segmentation doesn’t just require knowledge of the meanings of words. As we learn a language, we are learning transitional probabilities- the likelihood that one sound will follow another within a word.

Question 9

How do top down and bottom up processing influence language perception?

Answer 9

The continuous sound signal enters the ears and triggers signals that are sent to the brain (bottom up processing). If the individual understands the language, they are able to perceive the individual words using their prior knowledge (top down processing).

Question 10

Statistical learning

Answer 10

The process of learning about transitional probabilities and about other characteristics of language. Infants are capable of this at as young as 8 months old. One study found that infants listened longer to part word stimuli of nonsense words. Infants tend to lose interest in stimuli that are repeated.

Question 11

Likelihood principle/ Helmholtz’s theory of unconscious inference

Answer 11

Hemholtz- states that we perceive the object that is most likely to have caused the pattern of stimuli we received. Proposes that our knowledge of the environment enables us to determine what is most likely to have caused the image on the retina.

Question 12

How often do we make inferences to perceive things?

Answer 12

The judgment of which object is which most likely occurs by unconscious inference- our perceptions are the result of unconscious assumptions (inferences) we make about the environment. We infer what an image is based on experiences we’ve had. This involves an element of problem solving, even though perceptions seem instantaneous.

Question 13

Gestalt principles of organization

Answer 13

Based on the idea of structuralism- Gestalt psychologists believed that perceptions were formed by adding up sensations.

Question 14

Apparent movement illusion

Answer 14

when movement is perceived, but nothing is actually moving. There are 3 components of stimuli that create this illusion: one light flashes on and off, there is a period of darkness lasting a fraction of a second, and the second light flashes on and off. We don’t see the darkness in this illusion. Our perceptual system adds the perception of the light moving through the space between the flashing lights. This is an example of Gestalt psychology.

Question 15

What is a basic principle of Gestalt psychology?

Answer 15

A basic principle of Gestalt psychology is that the whole is different from the sum of its parts. This conclusion was drawn from the fact that the perceptual system creates the perception of movement from stationary images, when there are no actual sensations.

Question 16

Good continuation

Answer 16

Gestalt psychology- when points are connected to form straight or smoothly curving lines, they are seen as belonging together. The lines tend to be seen in such a way as to follow the smoothest path. Also, objects that are overlapped by other objects are perceived as continuing behind the overlapping object. We perceive our shoelaces as continuous even though we can’t see the whole lace when our shoes are tied.

Question 17

Pragnanz

Answer 17

Gestalt psychology- the law of pragnanz is also called the principle of good figure or the principle of simplicity. It states that every stimulus pattern is seen in such a way that the resulting structure is as simple as possible. For example, we see the Olympic 5 circle logo as five circles and not more complicated shapes.

Question 18

The principle of similarity

Answer 18

Gestalt psychology- similar things appear to be grouped together. We perceive an image as being grouped in rows rather than columns when similar shapes have been placed in a row

Question 19

Is Gestalt psychology based on top down or bottom up processing?

Answer 19

Bottom up- Gestalt principles are described as “intrinsic laws” built into the perceptual system. These psychologists believe that experiences influence perception, but that role is minor compared to perceptual principles.

Question 20

Physical regularities of the environment

Answer 20

Regularly occurring physical properties of the environment. For example, there are more vertical or horizontal orientations in the environment than oblique ones. This is true both in nature and in buildings. Examples include the oblique effect and the light from above assumption.

Question 21

The oblique effect

Answer 21

People can perceive horizontal and vertical orientations more easily than oblique ones.

Question 22

Light from above assumption

Answer 22

We usually assume that light is coming from above since that is where the light in our environment usually comes from. Ex- we assume the image (page 75) is either an indentation or a bump depending on where the light is coming from.

Question 23

Semantic regularities

Answer 23

Semantics refers to the meaning of a scene, which is usually referring to what’s happening in a scene. Semantic characteristics are the characteristics associated with the activities carried out in different areas/scenes, for example, cooking and eating occur in kitchens.

Question 24

How are human perceptual systems different from those of computers?

Answer 24

We have adapted to the physical characteristics of our environment, which is what influences some of our perceptions. What we have learned about the environment also influences our perceptions. These two things are what makes humans different from computers.

Question 25

Scene schema

Answer 25

The knowledge of what a given scene typically contains. For example, when asked to picture a microscope, you would probably picture it in a laboratory setting. If two objects look alike, you might perceive the object as something that fits in the scene rather than something that doesn’t.

Question 26

Bayesian inference

Answer 26

Thomas Bayes proposed that our estimate of the probability of an outcome is determined by two factors: the prior probability and the likelihood of the outcome. Work together to determine perception.

Question 27

Prior probability

Answer 27

Our initial belief about the probability of an outcome. While retinal images are ambiguous, we come to most perceptual situations with priors based on our past experiences.

Question 28

Likelihood of the outcome

Answer 28

The extent to which the available evidence is consistent with the outcome.

Question 29

Bayesian inference example

Answer 29

Mary believes that having a cold or heartburn is likely, but having lung disease is not. These are Mary’s priors, or her beliefs about frequency.
Mary notices that her friend Charles has a bad cough. She guesses that 3 possible causes are cold, heartburn, or lung disease. She does research and realizes that coughing can be associated with a cold or lung disease, but not heartburn. This new information is called the likelihood. The likelihood is combined with the priors, and Mary concludes that Charles probably has a cold.

Question 30

How do priors affect our perception?

Answer 30

While retinal images are ambiguous, we come to most perceptual situations with priors based on our past experiences. One prior we have is that books are rectangular. When we see a book, we believe that the book is probably rectangular. The likelihood that the book is rectangular is provided by more evidence, like the book’s retinal image, your perception of the book’s distance, and the angle you’re viewing the book from. If the evidence is consistent with the prior that the book is rectangular, then the likelihood is high and the perception “rectangular” is strengthened. This testing process occurs automatically and rapidly, so we aren’t aware of it.

Question 31

How does Bayesian inference compare to Hemholtz’s ideas and the principle of environmental regularities?

Answer 31

The Hemholtz, regularities, and Bayes approaches all have in common the idea that we use data about the environment, gathered through our past experiences in perceiving, to determine what we’re perceiving.
Therefore, top down processing is important.

Question 32

There are more neurons in animal and human visual cortexes that respond to horizontal and vertical orientations than to oblique (slanted) orientations. Why?

Answer 32

Horizontals and verticals are common features of the environment, and people are more sensitive to these orientations than to other orientations that aren’t as common. One possible explanation for why there are more horizontal and vertical neurons is the theory of natural selection- the characteristics that enhance an animal’s survival, and therefore their ability to reproduce, will be passed onto future generations. The trait that resulted in more neurons that fired in response to important things in the environment (verticals and horizontals) was selected for.

Question 33

Experience-dependent plasticity in humans

Answer 33

There is evidence from fMRI studies that this likely occurs in humans. The fusiform facial area (temporal lobe) contains many neurons that respond to faces. measured the level of activity in the FFA in response to faces but also to Greebles. Greebles are families of computer generated beings that have the same basic configuration but differ in the shapes of their parts just like faces do. For people who had less experience perceiving Greebles, the faces cause more FFA activity than the Greebles. After they were trained to recognize Greebles, the participants’ FFA responded almost as well to Greebles as it did to faces. Therefore, the objects to which the neurons respond best are established by experience with those objects. Since we have a lifetime of experience in recognizing faces, neurons in the FFA respond well to faces.

Question 34

How does experience dependent plasticity influence perception?

Answer 34

The brain can be trained to operate best in a specific environment, so the neurons will adapt to these regularities of the environment. An important purpose of perception is to allow us to interact with the environment.

Question 35

How does movement facilitate perception?

Answer 35

Movement helps us to perceive objects in the environment more accurately. This is because moving around reveals different viewpoints of an object that wouldn’t be visible if you were just standing in one place.

Question 36

How do perception and action interact?

Answer 36

Movement involves coordination between perceiving the stimuli and taking action to interact with those stimuli- to pick up a coffee cup, you perceive it first and then interact with it. This involves multiple different perceptions that influence your actions- positioning your fingers to grab the cup based on your perception of its handle, adjusting how much force you use based on your perception of its fullness, etc.

Question 37

Brain ablation

Answer 37

Removing part of the brain. This is done to determine the function of a certain area of the brain.

Question 38

Ungerleider and Mishkin study

Answer 38

Monkeys were given two tasks- an object discrimination and a landmark discrimination problem. During brain ablation, part of the temporal lobe was removed. The monkeys had trouble with the object discrimination problem after this. This indicates that the neural pathway that reaches the temporal lobe is responsible for determining an object’s identity.

Question 39

Ventral pathway

Answer 39

Also known as the “what pathway”. It is the the pathway from the striate cortex to the temporal lobe. Responsible for object discrimination, individuals with damage to this area will have trouble identifying objects.

Question 40

Dorsal pathway

Answer 40

Also known as the “where pathway”. It is the pathway from the striate cortex in the occipital lobe to the parietal lobe and is responsible for determining an object’s location. Individuals with damage to this area have difficulty with landmark discrimination.

Question 41

Patient DF

Answer 41

Patient DF experienced damage to her temporal lobe. She was unable to rotate a card to match the different orientations of a slot. However, when she was asked to “mail” the card through the slot, she was able to do it (after she had started moving the card toward the slot). She was unable to do static orientation matching, but did well once action was involved. These results suggested that there’s one mechanism for judging orientation and another for coordinating vision and action, like there is in monkeys.

Question 42

Perception pathway

Answer 42

The pathway from the visual cortex to the temporal lobe, corresponds to the what pathway. This was the pathway that was damaged for patient DF, causing her difficulty with static orientation matching.

Question 43

Action pathway

Answer 43

Also called the how pathway. The pathway from the visual cortex to the parietal lobe, corresponds to the where pathway.

Question 44

Mirror neurons

Answer 44

Mirror neurons are neurons that respond when the monkey picks up the food and when it observes someone else doing the same activity. They are likely involved in determining the goal or intention behind an action. There are multiple different intentions associated with the perception of the same action.

Question 45

Mirror neuron system

Answer 45

There is likely a network of mirror neurons distributed throughout the human brain.

Question 46

How do mirror neurons signal intentions?

Answer 46

One possibility is the response of these neurons is determined by the sequence of motor activities that could be expected to happen in a particular context. In this case, the neurons are responding to the action that is happening as well as the sequence of actions that are most likely to follow. If a person is picking up a coffee mug with the intention of drinking coffee, it would make sense that they would next drink the coffee.

Question 47

Sensation

Answer 47

Physical energy that we take from our environment and
translate into neural signals

Question 48

Vision

Answer 48

Takes up a large portion of the brain, can overrule the other senses

Question 49

Touch

Answer 49

Controlled by somatosensory cortex.

Question 50

Smell

Answer 50

Only sense connected to the forebrain, strongly connected to memory

Question 51

Taste

Answer 51

Lose half of our taste buds by 20

Question 52

What does it mean to perceive something?

Answer 52

The set of processes we use to interpret the different stimuli we’re presented with. Our perceptions are based on how we make sense of different sensations

Question 53

Recognition

Answer 53

The process of matching representations of organized sensory input to stored representations in memory. We get too much information at a given moment, so it’s impossible to process everything in the environment

Question 54

Figure ground

Answer 54

A Gestalt principle. The eye differentiates between an object form, silhouette, or shape, which is naturally perceived as the figure (object), while the surrounding area is perceived as ground (background). Two faces vs a vase example- you see one of these objects and then treat the other shape as the background.

Question 55

Closure

Answer 55

Closure occurs when an object is incomplete or a space is not completely
enclosed. If enough of the shape is indicted, people perceive the whole by filling in the missing information. We tend to perceive a line with gaps as a solid line or a full shape

Question 56

Proximity/nearness

Answer 56

Gestalt principle. When elements are placed close together, they tend to be perceived as a group. For example, a random number of squares will be perceived as part of a larger square when they are in close proximity to each other.

Question 57

Common fate

Answer 57

Gestalt principle. Entities that move together, are grouped together.

Question 58

McGurk effect

Answer 58

An illusion whereby speech sounds are often miscategorized when the auditory cues in the stimulus conflict with the visual cues from the speaker’s face