Ch. 3

Question 1

Learning Objectives

Answer 1

3-1
Describe the difference between sensation and perception.
3-2
Identify multiple reasons why it is difficult to create a “perceiving machine” even with recent advances in artificial intelligence and computer vision.
3-3
Describe the principles of perceptual organization, including good continuation, pragnanz, and similarity.
3-4
Explain why two people may perceive the same stimulus differently.
3-5
Describe the difference between bottom-up and top-down processing.
3-6
Explain how perception depends on a person’s knowledge of the environment.
3-7
Explain why the brain responds best to things that are likely to appear in the environment, often called physical regularities.
3-8
Discuss the role of the fusiform face area (FFA) as a visual expertise brain region.
3-9
Describe the connection between perception and action—and how they relate to the ventral (“what”) and dorsal (“where”) pathways.

Question 2

perception

Answer 2

Conscious experience that results from stimulation of the senses.

arriving at a perception can involve a process. And one that is similar to reasoning or problem solving.

perceptions can change based on added information.

perception occurs in conjunction with action.

In most cases, perception occurs so rapidly and effortlessly that it appears to be automatic. But it’s not.

It is important to recognize that while perception creates a picture of our environment and helps us take action within it, it also plays a central role in cognition in general.

When we consider that perception is essential for creating memories, acquiring knowledge, solving problems, communicating with other people, recognizing someone you met last week, and answering questions on a cognitive psychology exam, it becomes clear that perception is the gateway to all the other cognitions.

Question 3

sensation

Answer 3

The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment. It involves the detection of physical stimuli (such as light) by the sensory organs (such as eyes) and converting these stimuli into neural signals.

Question 4

Machine learning

Answer 4

A form of artificial intelligence that uses algorithms and statistical models enabling computers to perform specific tasks by learning from data and improve their performance over time (instead of using explicit instructions).

Question 5

deep learning

Answer 5

A form artificial intelligence that uses neural networks with many layers (hence the term “deep”) to model complex patterns in large datasets. Deep learning algorithms are particularly powerful for tasks involving high-dimensional data, such as image and speech recognition and natural language processing.

Question 6

inverse projection problem

Answer 6

Task of determining the object that caused a particular image on the retina.

Question 7

Occlusion

Answer 7

The perceptual phenomenon in which part or all of an object or scene are obscured (blocked or hidden) from view.

Question 8

viewpoint invariance

Answer 8

The ability to recognize an object seen from different viewpoints.

Question 9

The difficulties facing any perceiving machine illustrate the process of perception is more complex than people may first suspect.

Answer 9

Our task, therefore, in describing perception is to explain this process, focusing on how the “human perceiving machine” operates.

We begin by considering the following two types of information used by the human perceptual system:

(1)
environmental energy that stimulates receptors and

(2)
knowledge and expectations that the observer contributes to the situation.

Question 10

bottom-up processing

Answer 10

Processing that starts with information received by the receptors. This type of processing is also called data-based processing.

Looking at something creates an image on the retina.

This image generates electrical signals that are transmitted through the retina, and then to the visual receiving area of the brain.

This sequence of events from eye to brain is called bottom-up processing because it starts at the “bottom” or beginning of the system when environmental energy stimulates the receptors.

Question 11

top-down processing

Answer 11

Processing that involves a person’s knowledge or expectations. This type of processing has also been called knowledge-based processing.

This knowledge enables people to rapidly identify objects and scenes, and also to go beyond mere identification of objects to determining the story behind a scene.

Question 12

Perceiving Objects

An example of top-down processing, “the multiple personalities of a blob,”

Answer 12

because even though all of the blobs are identical, they are perceived as different objects depending on their orientation and the context within which they are located.

We perceive the blob as different objects because of our knowledge of the kinds of objects that are likely to be found in different types of scenes.

The human advantage over computers is therefore due, in part, to the additional top-down knowledge available to humans.

Question 13

speech segmentation

Answer 13

The process of perceiving individual words within the continuous flow of the speech signal.

Question 14

transitional probabilities

Answer 14

In speech, the likelihood that one speech sound will follow another within a word.

Question 15

statistical learning

Answer 15

The process of learning about transitional probabilities and about other characteristics of language. Statistical learning also occurs for vision, based on learning about what types of things usually occur in the environment.

Question 16

Hermann von Helmholtz

Answer 16

1821–1894

physicist

One of Helmholtz’s contributions to perception was based on his realization that the image on the retina is ambiguous.

We have seen that ambiguity means that a particular pattern of stimulation on the retina can be caused by an infinite number of possible objects in the environment.

Helmholtz’s question was, how does the perceptual system “decide” that this pattern on the retina was created by overlapping rectangles?

His answer was the likelihood principle.

An important feature of Helmholtz’s proposal is that this process of perceiving what is most likely to have caused the pattern on the retina happens rapidly and unconsciously. These unconscious assumptions, which are based on the likelihood principle, result in perceptions that seem “instantaneous,” even though they are the outcome of a rapid process.

Question 17

likelihood principle

Answer 17

Part of Helmholtz’s theory of unconscious inference that states that we perceive the object that is most likely to have caused the pattern of stimuli we have received.

According to Helmholtz, this judgment of what is most likely occurs by a process called unconscious inference

Question 18

unconscious inference

Answer 18

Helmholtz’s idea that some of our perceptions are the result of unconscious assumptions that we make about the environment.

Question 19

Gestalt psychologists

Answer 19

A group of psychologists who proposed principles governing perception, such as laws of organization, and a perceptual approach to problem-solving involving restructuring.

About 30 years after Helmholtz proposed his theory of unconscious inference.

The Gestalt approach to perception originated, in part, as a reaction to Wilhelm Wundt’s structuralism.

The Gestalt psychologists rejected the idea that perceptions were formed by “adding up” sensations.

main point is the Gestalt psychologists realized perception is based on more than the pattern of light and dark on the retina.

In their conception, perception is determined by specific principles that organize visual information.

Max Wertheimer (1912) describes these principles as “intrinsic laws,” which implies that they are built into the system.

This idea that the principles are “built in” is consistent with the Gestalt psychologists’ idea that although a person’s experience can influence perception, the role of experience is minor compared to the perceptual principles

Question 20

apparent movement

Answer 20

An illusion of movement perception that occurs when stimuli in different locations are flashed one after another with the proper timing.

movement is perceived, nothing is actually moving. Three components to stimuli create apparent movement:

(1)
One light flashes on and off

(2)
there is a period of darkness, lasting a fraction of a second and

(3)
the second light flashes on and off

Physically, therefore, two lights are flashing on and off separated by a period of darkness. But we don’t see the darkness because our perceptual system adds something during the period of darkness—the perception of a light moving through the space between the flashing lights.

Wertheimer drew two conclusions:

His first conclusion was that apparent movement cannot be explained by sensations because there is nothing in the dark space between the flashing lights.

His second conclusion became one of the basic principles of Gestalt psychology: The whole is different than the sum of its parts.

Question 21

principles of perceptual organization

Answer 21

principles of Rules proposed by the Gestalt psychologists to explain how small elements of a scene or a display become perceptually grouped to form larger units. These “laws” are described as “heuristics” in this book.

Question 22

principle of good continuation

Answer 22

Law of perceptual organization stating that points that, when connected, result in straight or smoothly curving lines are seen as belonging together. In addition, lines tend to be seen as following the smoothest path.

Question 23

law of pragnanz

Also called principle of good figure or the principle of simplicity

Answer 23

Law of perceptual organization that states that every stimulus pattern is seen in such a way that the resulting structure is as simple as possible. Also called the law of good figure and the law of simplicity.

The familiar Olympic symbol is an example of the law of simplicity at work. We perceive this display as five circles and not as a larger number of more complicated shapes.

Question 24

principle of similarity

Answer 24

Law of perceptual organization that states that similar things appear to be grouped together.

Question 25

regularities in the environment

Answer 25

Characteristics of the environment that occur frequently.

Question 26

Physical regularities

Answer 26

Regularly occurring physical properties of the environment. For example, there are more vertical and horizontal orientations in the environment than oblique (angled) orientations. This occurs in human-made “carpentered” environments (for example, buildings contain lots of horizontals and verticals and also in natural environments (trees, plants, and land are more likely to be vertical and horizontal. Humans are not born with knowledge of these physical regularities. Instead, this knowledge is gained through observation of the physical regularities in the environment.

Question 27

oblique effect

Answer 27

The finding that vertical and horizontal orientations can be perceived more easily than other (slanted) orientations.

Question 28

light-from-above assumption

Answer 28

The assumption that light is coming from above. This is a heuristic that can influence how we perceive three-dimensional objects that are illuminated. Our perception of illuminated shapes is influenced by how they are shaded, combined with the brain’s assumption that light is coming from above.

Question 29

One of the reasons humans can perceive and recognize objects and scenes so much better than computer-guided robots

Answer 29

is that our system is adapted to respond to the physical characteristics of our environment, such as the orientations of objects and the direction of light. But this adaptation goes beyond physical characteristics. It also occurs because, as we observed when we considered the multiple personalities of a blob, we have learned about what types of objects typically occur in specific types of scenes.

Question 30

Semantic Regularities

Answer 30

Characteristics associated with the functions carried out in different types of scenes. For example, food preparation, cooking, and perhaps eating occur in a kitchen. Semantics applies to our perception of assigning meaning to, or understanding what happens in, a scene.

Question 31

scene schema

Answer 31

A person’s knowledge about what is likely to be contained in a particular scene. This knowledge can help guide attention to different areas of the scene. For example, knowledge of what is usually in an office may cause a person to look toward the desk to see the computer.

Question 32

Bayesian inference

Answer 32

The idea that our estimate of the probability of an outcome is determined by the prior probability (our initial belief) and the likelihood (the extent to which the available evidence is consistent with the outcome). the prior probability , or simply the prior , which is our initial belief about the probability of an outcome, and the extent to which the available evidence is consistent with the outcome. = likelihood was named after Thomas Bayes (1701–1761) involves a mathematical procedure in which the prior is multiplied by the likelihood to determine the probability of the outcome. Thus, people start with a prior and then use additional evidence to update the prior and reach a conclusion. What Bayesian inference does is to restate Helmholtz’s idea—that we perceive what is most likely to have created the stimulation we have received—in terms of probabilities. have used it to develop computer-vision systems that can apply knowledge about the environment to more accurately translate the pattern of stimulation on their sensors into conclusions about the environment.

Question 33

Helmholtz’s unconscious inference, The Gestalt laws of organization, Regularities in the environment, Bayesian inference Which one is different from the other three?

Answer 33

Helmholtz, regularities, and Bayes all share the idea that we use data about the environment, gathered through our past experiences in perceiving, to determine what is out there. Top-down processing is therefore an important part of these approaches. Gestalt psychologists, in contrast, emphasized the idea that the principles of organization are built in. They acknowledged that perception is affected by experience but argued that built-in principles can override experience, thereby assigning bottom-up processing a central role in perception. modern psychologists have pointed out that the laws of organization could, in fact, have been created by experience. one way to look at the Gestalt principles is that they describe the operating characteristics of the human perceptual system, which happen to be determined at least partially by experience.

Question 34

Neurons That Respond to Horizontals and Verticals

Answer 34

When we described physical regularities in the environment, we mentioned that horizontals and verticals are common features of the environment and behavioral experiments have shown that people are more sensitive to these orientations than to other orientations that are not as common (the oblique effect). Found more neurons that respond best to horizontals and verticals than neurons that respond best to oblique orientations. The oblique effect can be weakened, Bayesian inference can also be used to help more accurately recall oblique line orientations. _{Two groups of participants were asked to accurately report the angle of various oblique lines. One group was given an oblique line as a point of reference, but the other group was not. The participants that had a point of reference could better estimate likelihoods using Bayesian inference, leading to more accurate reporting of line orientation.}

Question 35

theory of natural selection

Answer 35

Why are there more neurons that respond to horizontals and verticals? One possible answer is based on the theory of natural selection , which states that characteristics that enhance an animal’s ability to survive, and therefore reproduce, will be passed on to future generations.

Question 36

Experience-Dependent Plasticity

Answer 36

The brain’s functioning can be “tuned” to operate best within a specific environment. Thus, continued exposure to things that occur regularly in the environment can cause neurons to become adapted to respond best to these regularities. Blakemore and Cooper’s (1970) experiment in which they showed that rearing cats in horizontal or vertical environments can cause neurons in the cat’s cortex to fire preferentially to horizontal or vertical stimuli. This shaping of neural responding by experience, which is called experience-dependent plasticity, provides evidence that experience can shape the nervous system. The particular objects to which the neurons respond best are established by experience with the objects. Just as rearing kittens in a vertical environment increased the number of neurons that responded to verticals, training humans to recognize Greebles, cars, or birds causes the FFA to respond more strongly to these objects. These results support the idea that neurons in the FFA respond strongly to faces because we have a lifetime of experience perceiving faces.

Question 37

“What is the purpose of perception?”

Answer 37

One possible answer is that the purpose of perception is to create our awareness of what is happening in the environment, as when we see objects in scenes or when we perceive words in a conversation. But it becomes obvious that this answer doesn’t go far enough, when we ask, why it is important that we can experience objects in scenes and words in conversations? The answer to that question is that an important purpose of perception is to enable us to interact with the environment. The key word here is interact because interaction implies taking action.

Question 38

Movement Facilitates Perception

Answer 38

Although movement adds a complexity to perception that is not there when we are sitting in one place, movement can also help us perceive objects in the environment more accurately. One reason this occurs is that moving reveals aspects of objects that are not apparent from a single viewpoint. Our concern with movement extends beyond noting that it helps us perceive objects by revealing additional information about them. Movement is also important because of the coordination that is continually occurring between perceiving stimuli and interacting with these stimuli. Picking up a cup of coffee: (a) perceiving and recognizing the cup; (b) reaching for it; and (c) grasping and picking it up. This action involves coordination between perceiving and action that is carried out by two separate streams in the brain, as described in the text.

Question 39

Perception and Action: Physiology

Answer 39

1980s This research has shown that there are two processing streams in the brain—one involved with perceiving objects, and the other involved with locating and interacting with these objects. This physiological research involves two methods: brain ablation—the study of the effect of removing parts of the brain in animals, and neuropsychology—the study of the behavior of people who experienced traumatic injury that damaged the brain. Both methods demonstrate how studying the functioning of animals and humans with brain damage can reveal important principles about the functioning of the normal (intact) brain.

Question 40

brain ablation

Answer 40

the study of the effect of removing parts of the brain in animals

Question 41

Leslie Ungerleider and Mortimer Mishkin (1982)

Answer 41

studied how removing part of a monkey’s brain affected its ability to identify an object and to determine the object’s location. This experiment used a technique called brain ablation. two tasks: (1) an object discrimination problem -A monkey was shown one object, such as a rectangular solid, and was then presented with a two-choice task which included the “target” object (the rectangular solid) and another stimulus, such as the triangular solid. -If the monkey pushed aside the target object, it received the food reward that was hidden in a well under the object. -Temporal lobe removed makes this task difficult to complete, but can do other task fine (2) a landmark discrimination problem. -Here, the tall cylinder is the landmark, which indicates the food well that contains food. -The monkey received food if picked food well closer to cylinder. -parietal lobe removed made this task difficult to complete, but other task easy to complete. Goal determine function of a particular area of the brain, accomplished by first determine an animals capacity by testing it behaviourally. Once animals perception has been measured, a particular area of the brain is ablated. Ideally 1 particular are is removed and rest of the brain intact. After ablation, monkey is tested to determine which perceptual capacities remain and which have been affected.

Question 42

object discrimination problem

Answer 42

A problem in which the task is to remember an object based on its shape and choose it when presented with another object after a delay. Associated with research on the what processing stream.

Question 43

landmark discrimination problem

Answer 43

Problem in which the task is to remember an object’s location and to choose that location after a delay. Associated with research on the where processing stream.

Question 44

“what” / ventral pathway

Answer 44

Neural pathway, extending from the occipital lobe to the temporal lobe, that is associated with perceiving or recognizing objects. Corresponds to the perception pathway. part of the temporal lobe was removed in some monkeys. Behavioral testing showed that the object discrimination problem became very difficult for the monkeys when their temporal lobes were removed. This result indicates that the neural pathway that reaches the temporal lobes is responsible for determining an object’s identity. what are gills for on a shark? Gills are vents! That will help you remember that the ventral pathway relates to “what” information and that they pathway is on the side/bottom of the brain (where the gills would be).

Question 45

“where” / dorsal pathway

Answer 45

Neural pathway, extending from the occipital lobe to the parietal lobe, that is associated with neural processing that occurs when people locate objects in space. Roughly corresponds to the action pathway. Other monkeys, which had their parietal lobes removed, had difficulty solving the landmark discrimination problem. This result indicates that the pathway that leads to the parietal lobe is responsible for determining an object’s location. where is the dorsal fin on a shark? It’s on the top! Now you know the dorsal pathway pertains to “where” information and that the pathway is on the top of the brain.

Question 46

“perception” pathway

Answer 46

Neural pathway, extending from the occipital lobe to the temporal lobe, that is associated with perceiving or recognizing objects. Corresponds to the what pathway. Milner and Goodale suggested

Question 47

“action” pathway

Answer 47

Neural pathway, extending from the occipital lobe to the parietal lobe, that is associated with neural processing that occurs when people take action. Corresponds to the where pathway.

Question 48

With our knowledge that perception and action involve two separate mechanisms, we can add physiological notations to our description of picking up the coffee cup

Answer 48

(1) The first step is to identify the coffee cup among the vase of flowers and the glass of orange juice on the table (“perception” or “what” pathway). (2) Once the coffee cup is perceived, we reach for the cup (“action” or “where” pathway), taking into account its location on the table. (3) As we reach, avoiding the flowers and orange juice, we position our fingers to grasp the cup (“action” pathway), taking into account our perception of the cup’s handle (“perception” pathway), and (4) We lift the cup with just the right amount of force (“action” pathway), taking into account our estimate of how heavy it is based on our perception of the fullness of the cup (“perception” pathway).

Question 49

Mirror Neurons

Answer 49

Neurons in the premotor cortex, originally discovered in the monkey, that respond both when a monkey observes someone else (usually the experimenter) carrying out an action and when the monkey itself carries out the action. There is also evidence for mirror neurons in humans.

Question 50

mirror neuron system (MNS)

Answer 50

A network of neurons in the brain that have mirror neuron properties. work done using functional magnetic resonance imaging (fMRI) in neurologically healthy people has further suggested that these neurons are distributed throughout the brain in a network that has been called the mirror neuron system (MNS)

Question 51

What is the purpose of these mirror neurons?

Answer 51

One suggestion is that they are involved in determining the goal or intention behind an action. If mirror neurons do, in fact, signal intentions, how do they do it? One possibility is that the response of these neurons is determined by the sequence of motor activities that could be expected to happen in a particular context