3.4 - Conceptions of Object Perception

Question 1

An early idea about how people use information was prosed by 19th century physicist and physiologist called?

Answer 1

Hermann von Helmholtz (1866/1911).

Question 2

Why was Herman von Helmholtz important?

Answer 2

• He was a physicist who made important contributions to fields as diverse as thermodynamics, nerve physiology, visual perception and aesthetics.
• One of Helmholtz’s contributions to perception was based on his realization that the image on the retina is ambiguous

Question 3

See ambiguity means that:

Answer 3

particular pattern of stimulation on the retina can be caused by a large number of objects in the environment

Question 4

Example of ambiguity

Explain

Answer 4

what does the pattern of stimulation in Figure 3.16a represent?

For most people, this pattern on the retina results in the perception of a blue rectangle in front of a red rectangle, as shown in Figure 3.16b. But as Figure 3.16c indicates, this display could also have been caused by a six-sided red shape positioned in front of, behind, or right next to the blue rectangle.

Question 5

What was Helmholtz’s question and answer

Answer 5

how the perceptual system “decides” that this pattern on the retina was created by overlapping rectangles?

The answer is likelihood principle

Question 6

What is the likelihood principle?

Answer 6

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.

Question 7

What process did Helmholtz say that the judgement of what most likely occurs by?

Answer 7

Unconscious inference

Question 8

What is unconscious inference?

Answer 8

our perceptions are the result of unconscious assumptions, or inferences, that we make about the environment

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

Question 9

How would unconscious interference be seen in figure below

Answer 9

Thus, we infer that it is likely that Figure 3.16a is a rectangle covering another rectangle because of experiences we have had with similar situations in the past.

Question 10

Helmholtz’s description of process of perception resembles the process involved solving a problem

For perception e,g

Answer 10

For perception, the problem is to determine which object has caused a particular pattern of stimulation, and this problem is solved by a process in which the perceptual system applies the observer’s knowledge of the environment in order to infer what the object might be.

Question 11

What is an important feature of Helmholtz’s proposal?

Answer 11

1. process of perceiving what is most likely to have caused the pattern on the retina happens rapidly and unconsciously.
2. unconscious assumptions, which are based on the likelihood principle, result in perceptions that seem “automatic,” even though they are the outcome of a rapid process
3. you might have been able to “automatically” solve the perceptual puzzles in the scene in Figure 3.2, this ability, according to Helmholtz, is the outcome of a rapid process that we are unaware of.

Question 12

What happened after 30 years of Helmholtz’s proposed the theory of unconscious interference?

Answer 12

Work of Gestalt psychologists

Question 13

What are Gestalt psychologists?

Answer 13

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

Question 14

How did Gestalt approach of perception orginated?

Answer 14

part, as a reaction to Wilhelm Wundt’s structuralism

e.g analytic introspection and structuralism

REMEMBER:

Wundt proposed that our overall experience could be understood by combining basic elements of experience called sensations.

Question 15

What did Gestalt psychologists reject Wundt’s idea?

Answer 15

perceptions are formed by simply “adding up” sensations. Indeed, this group of psychologists was among the first to suggest that the whole is more than the sum of its parts (the German word gestalt means “whole”).

Question 16

What did Gestalt psychplogists proose?

Answer 16

principles of perceptual organization to explain the way elements are grouped together to create larger objects.

Question 17

What are principles of perceptual organisation?

Answer 17

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 18

Diagram of 3.17

Answer 18

For example, in Figure 3.17, some of the black areas become grouped to form a Dalmatian and others are seen as shadows in the background.

Question 19

What does the principle of good continuation state?

Answer 19

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 20

Example of continuation

Answer 20

Emma saw the coiled rope in Figure 3.1c, she wasn’t surprised that when she grabbed one end of the rope and flipped it, it turned out to be one continuous strand (Figure 3.18). The reason this didn’t surprise her is that even though there were many places where one part of the rope overlapped another part, she didn’t perceive the rope as consisting of a number of separate pieces; rather, she perceived the rope as continuous.

Question 21

What does pragnaz roughly transalte from German?

Answer 21

good figure.

Question 22

What does law of pragnaz/principle of good figure/principle of simplicity state?

Answer 22

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.

Question 23

Example of principle of good figure

Answer 23

an example of the law of simplicity at work. We see this display as five circles and not as a larger number of more complicated shapes such as the ones shown in the “exploded” view of the Olympic symbol in Figure 3.19b. The law of good continuation also contributes to perceiving the five circles.

Question 24

What is principle of similarity?

Answer 24

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

Question 25

Example of good simiilarity

Answer 25

Most people perceive Figure 3.20a as either horizontal rows of circles, vertical columns of circles, or both. But when we change the colour of some of the columns, as in Figure 3.20b, most people perceive vertical columns of circles

Question 26

Another example of similairty

Answer 26

A striking example of grouping by similarity of colour is shown in Figure 3.21. Grouping can also occur because of similarity of size, shape, or orientation.

Question 27

Main purpose of Gestalt psychologist?

Answer 27

realized that visual perception is based on more than just the pattern of light and dark on the retina. In their conception, perception is determined by specific organizing principles.

Question 28

Where do these organising principles come from?

Answer 28

• 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,
• idea that experience plays only a minor role in perception differs from Helmholtz’s likelihood principle, which proposes that our knowledge of the environment enables us to determine what is most likely to have created the pattern on the retina. In agreement with Helmholtz, modern perceptual psychologists also see our experience with the environment as a central component of the process of perception.

Question 29

Modern cognitive psychologists introduced that perception is influenced by our knowledge of:

Answer 29

regularities in the environment

Question 30

Definition of regularities in the environment

Answer 30

Characteristics of the environment that occur frequently. For example, blue is associated with open sky, landscapes are often green and smooth, and verticals and horizontals are often associated with buildings.

Question 31

What are two types of regularities?

Answer 31

physical regularities and semantic regularities.

Question 32

What are physical regularities?

Answer 32

Regularly occurring physical properties of the environment. For example, there are more vertical and horizontal orientations in the environment than oblique (angled) orientations.

Question 33

Example of physical regularities

Answer 33

his occurs in human-made environments (for example, buildings contain lots of horizontals and verticals) and also in natural environments (trees and plants are more likely to be vertical or horizontal than slanted)

Question 34

What is the oblique effect?

Answer 34

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

Question 35

Example of physical regularities

Answer 35

• two textured protrusions jutting out from a wall. But when the picture is turned upside down, as in Figure 3.23b, the protrusions appear reversed—now the textured surface appears indented.
• Our perception in these two situations has been explained by the light-from-above assumption: We usually assume that light is coming from above, because light in our environment, including the sun and most artificial light, usually comes from above (Kleffner & Ramachandran, 1992).
• . Figure 3.23c shows how light from above would hit the top surface of a protrusion to result in the right-side-up perception. Figure 3.23d shows how light from above would hit the lower surface of a recess to result in the upside-down perception.

Question 36

What is light-from-above assumption?

Answer 36

The assumption that light is coming from above. This is a heuristic that can influence how we perceive three-dimensional objects that are illuminated.

Question 37

One of the reasons humans are able to perceive and recognize objects and scenes so much better than computer-guided robots is that our system is adapted

Answer 37

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 we have learned about what types of objects typically occur in specific types of scenes.

Question 38

What does semantic mean?

Answer 38

meanings of words or sentences.

Question 39

What are semantic regularities?

Answer 39

Characteristics associated with the functions carried out in different types of scenes. For example, food preparation, cooking and perhaps eating occur in a kitchen.

Question 40

What is scene schema?

Answer 40

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 41

Example of scene schema influence perception

Palmer’s experiment

Answer 41

• first presented a context scene such as the one on the left and then briefly flashed one of the target pictures on the right.
• observers were asked to identify the object in the target picture, they correctly identified an object like the loaf of bread (which is appropriate to the kitchen scene) 80 per cent of the time,
• correctly identified the mailbox or the drum (two objects that don’t fit into the scene) only 40 per cent of the time.’
• Apparently the observers were using their scene schema for kitchens to help them perceive the briefly flashed loaf of bread.

Question 42

Two ideas described

Answer 42

(1)

Helmholtz’s idea that we resolve the ambiguity of the retinal image by inferring what is most likely, given the situation; and

(2)

the idea that regularities in the environment provide information we can use to resolve ambiguities—are the starting point for our last approach to object perception: Bayesian inference (Geisler, 2008, 2011; Kersten, Mamassian, & Yuille, 2004; Yuille & Kersten, 2006).

Question 43

What is Bayesian inference named after and who proposed that our estimate of the probability of an outcome is determined by two factors:

Answer 43

named after Thomas Bayes (1701–1761),

(1)

the prior probability, or simply the prior, which is our initial belief about the probability of an outcome, and

(2)

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

Question 44

What is Bayesian inference?

Answer 44

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).

Question 45

What is prior probability?

Answer 45

A person’s initial belief about the probability of an outcome.

Question 46

What is second factor Thomas Bayes prorposed called?

Answer 46

In Bayesian inference, the extent to which the available evidence is consistent with the outcome.

CALLED LIKELHOOD

Question 47

Example of Bayesian interference

Answer 47

Stella believes that having a cold or heartburn is likely to occur, but having lung disease is unlikely. With these prior probabilities in her head (along with lots of other beliefs about health-related matters), Stella notices that her friend Simon has a bad cough. She guesses that three possible causes could be a cold, heartburn, or lung disease. Looking further into possible causes, she does some research and finds that coughing is often associated with having either a cold or lung disease, but isn’t associated with heartburn (Figure 3.25b). This additional information, which is the likelihood, is combined with Stella’s prior probability to produce the conclusion that Simon probably has a cold

Bayesian inference involves a mathematical procedure in which the prior probability is multiplied by the likelihood to determine the probability of the outcome. Thus, people start with a prior probability, then use additional evidence to update this initial belief about the probability of a certain outcome and reach a conclusion (Körding & Wolpert, 2006).

Question 48

How is Bayesian idea similar to Helmholtz’s idea?

+ different’

Answer 48

that we perceive what is most likely to have created the stimulation we have received—in terms of probabilities. It isn’t always easy to specify these probabilities, particularly when considering complex perceptions

+ different

Bayesian inference provides a specific procedure for determining what might be out there, researchers 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 49

How is Helmholtz and Bayes common

Answer 49

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.

Question 50

How is Gestalt Psychologists differ?

Answer 50

emphasized the idea that the principles of organization are built-in. They acknowledged that perception is affected by the experience, but argued that built-in principles can override experience, thereby assigning bottom-up processing a more central role in perception than the other three approaches do

Question 51

Gestalt following example

following example to illustrate how built-in principles could override experience:

Answer 51

W and M based on their past experience with these letters. However, when the letters are arranged as in Figure 3.26b, most people see two uprights plus a pattern between them. The uprights, which are created by the principle of good continuation, are the dominant perception and override the effects of past experience we have had with Ws and Ms

Question 52

Modern psychologists vs Gestalt psychologists

Answer 52

Gestalt psychologists de-emphasized experience, using arguments like the one above, modern cognitive psychologists have pointed out that the laws of organization could, in fact, have been created by experience

Question 53

Example laws of organisation in fact have been created by the experience

Answer 53

principle of good continuation has been determined by experience with the environment.

From years of experience in seeing objects that are partially covered by other objects, we know that when two visible parts of an object have the same colour (principle of similarity) and are “lined up” (principle of good continuation), they belong to the same object and extend behind whatever is blocking it. Thus, 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. In fact, there is physiological evidence supporting the idea that experiencing certain stimuli over and over again can actually shape the way neurons respond in perceptual systems. We will consider this physiological approach to perception next.

Question 54

It is just about time for Samuel to receive the weekly call from his mother that has occurred for nearly two years, so when he answers the phone and hears a female voice, he says, “It’s the best mum in the world calling me.” As it happens, it is the TA from his cognitive psychology class who is returning a call from him. He swears up and down that she really does sound just like his mother. Samuel has fallen prey to Helmholtz’s

Answer 54

likelihood principle.

According to Helmholtz’s likelihood principle, we perceive what is most likely to have caused a particular stimulus pattern. Since it is most likely his mother calling, Paxton perceives his TA’s voice as his mother’s voice.

Question 55

For centuries, people have created images in the night sky by connecting the stars into constellations illustrating various animals like bears, dogs, or eagles as well as various deities or protagonists. The tendency to connect together points that, when joined, result in straight or smoothly curving lines, and perceive the points as belonging together, is known as the principle of

Answer 55

good continuation

According to the principle of good continuation, points that, when connected, result in straight or smoothly curving lines are seen as belonging together, and the lines tend to be seen in such a way as to follow the smoothest path.

Question 56

Megan has a terrible stress-related headache, one of the worst she has ever had. While taking a break from working on a tough term paper, Megan googles her symptoms (e.g., sick to her stomach, dizzy, headache) and finds mention after mention of brain tumors. In fact, nearly three out of four of the hits are about brain tumors, although the majority of the others are stress-related headaches. Suddenly, Megan wonders whether she has a brain tumor. This is most consistent with

Answer 56

Bayesian inference.

Bayesian inference is the idea that we estimate the probability of an outcome (having a brain tumor) based on our belief about the probability of an outcome and the extent to which the available evidence is consistent with the outcome. Since Megan has seen many instances in which the symptoms she is experiencing turn out to be associated with a brain tumor, she becomes concerned about the possibility of a brain tumor.