Chapter 3- Perception

Question 1

Perception

Answer 1

Conscious experience that results from stimulation of the senses, how we process sensations

Question 2

Basic concepts of perception

Answer 2

1. perceptions can change based on added information; takes into account prior experiences, context; prior knowledge and expectancies affect our interactions with ambiguous stimuli
2. involves a process similar to reasoning or problem solving; trying to figure out what is in our environment
3. perceptions occur in conjunction with actions; shaped by our interactions with objects

Question 3

why is it difficult to create a perceiving machine?

Answer 3

1. inverse projection problem
2. objects can be hidden or blurred (any time one object obscures part of another object) – people easily understand that the part of an object that is covered continues to exists
3. Viewpoint variance – objects look different from different viewpoints

Question 4

the inverse projection problem

Answer 4

task of determining the object that caused a particular image on the retina. Involves starting with the retinal image and then extending outward to the source of that image

Question 5

viewpoint invariance

Answer 5

the ability to recognize an object seen from different viewpoints

Question 6

bottom-up processing

Answer 6

processing that starts with information received by the receptors. ex. For Gil to see Mary the first step is light reflecting from Mary input into the retina, which generates an image on the retina

Question 7

top-down processing

Answer 7

processing that originates in the brain and involves a person’s knowledge or expectations. ex. Gill knows things about Mary, has general expectations, and pays attention to her specific features

Question 8

direct perception theories

Answer 8

•Bottom-up processing
•Perception comes from stimuli in the environment
oPerception may start with the senses
oOur perceptual system is tuned to particular objects
•Parts are identified and put together, and then recognition occurs
•Perception is less of an inferential process, and more of just taking in objects from the environment
•We simply have senses that are tuned to particular kinds of objects

Question 9

Constructive perception theories

Answer 9

•More familiar way of thinking about things
•Top-down processing
•People actively construct perceptions using information based on expectations
oPerception may start with the brain
oPerson’s knowledge, experience, expectations

Question 10

recognition-by-components

Answer 10

Biederman: we perceive objects by perceiving elementary features. These building blocks can be combined to create objects

Question 11

complexity of perception

Answer 11

Perception is hard and highly context dependent. The same input is interpreted in very different ways depending on the environment

Question 12

speech segmentation

Answer 12

the process of perceiving individual words within the continuous flow of the speech signal. the fact that a listener familiar only with English and another listener familiar with Spanish can receive identical sound stimuli but experience different perceptions means that each listener’s experience with language is influencing his or her perception

Question 13

direct pathway model

Answer 13

(early theory) bottom-up model of pain perception that proposes that pain signals are sent directly from receptors in the skin called nociceptors to the brain

Question 14

modern research on pain experience

Answer 14

More recent models have found that expectations, attention, and distraction can affect how we experience pain in a “top down” manner

Question 15

Helmholtz’ Theory of Unconscious Inference

Answer 15

Top-down theory; we use knowledge to inform our percepts and some of our perceptions are the result of unconscious assumptions we make about the environment. We infer much of what we know about the world

Question 16

“Problem” of perception

Answer 16

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 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 received

Question 18

unconscious inference

Answer 18

Helmholtz’ 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 perceptions (rejected the idea of structuralism, that perceptions were formed by adding up sensations)
The mind groups patterns according to laws of perceptual organization and the brain tells us what’s important and we focus on that

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.
1) one light flashes on and off
2) there is a period of darkness, lasting a fraction of a second
3) the second light flashes on and off
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

Question 21

principles of perceptual organization

Answer 21

grew out of Wertheimer’s conclusion that the whole is different than the sum of its parts; rules proposed by the Gestalt psychologists to explain how small elements of a scene or a display become perceptually grouped to form larger units

Question 22

principle of good continuation

Answer 22

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. Also, objects that are overlapped by other objects are perceived as continuing behind the overlapping object. Ex: coiled rope (bottom-up mechanism)

Question 23

law of pragnanz/principle of good figure/simplicity

Answer 23

every stimulus pattern is seen in a way that the resulting structure is as simple as possible. Ex: olympic symbol

Question 24

principle of similarity

Answer 24

similar things appear to be grouped together. can be grouped by color, size, shape, orientation

Question 25

Gestalt laws of perceptual organization

Answer 25

experience is important, but does not overcome perceptual principles. These laws are intrinsic and the role of experience is minor

Question 26

regularities in the environment

Answer 26

characteristics of the environment that occur frequently

Question 27

physical regularities

Answer 27

regularly occurring physical properties of the environment

Question 28

oblique effect

Answer 28

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

Question 29

light-from-above assumption

Answer 29

the assumption that light is coming from above. This is a heuristic that can influence how we perceive 3D objects that are illuminated. We perceive shadows as specific information about depth and distance

Question 30

semantic regularities

Answer 30

characteristics associated with the functions carried out in different types of scenes. the meaning of a given scene is related to what is happening within that 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.

Question 32

Palmer Experiment

Answer 32

1975: scenes were shown for 2 seconds to provide a context and participants were then shown and object and asked to ID it. most likely to ID an object correctly after seeing an appropriate context

Question 33

Inferential Approach

Answer 33

1. Helmholtz's idea that we resolve ambiguities by the most-likely principle 2. Regularities in the environment provide information for how the ambiguities can be resolved So, to refine our definition of "Perception": Given an image (input) and the knowledge about regularities of the physical world, pick the most probable interpretation of the image.

Question 34

Bayesian inference

Answer 34

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). Restates Helmholtz's idea - that we perceive what is most likely to have created the stimulation we have received - in terms of probabilities

Question 35

prior probability

Answer 35

a person's initial belief about the probability of an outcome. People start with a prior, and then use additional evidence to update the prior and reach a conclusion

Question 36

likelihood

Answer 36

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

Question 37

Comparing the 4 Approaches

Answer 37

The approaches of Helmholtz, regularities, and Bayes all have in common 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 an important part of these approaches. The Gestalt psychologists emphasized the idea that the principles of organization are built in. Perception is affected by experience, but built-in principles can override experience; bottom-up processing

Question 38

Culture and Perception

Answer 38

The dominate view is that tasks involving low-level cognitive processes, such as vision, should not vary much across the human spectrum. In Bayesian terms, our priors are determined by our experience with a particular kind of built environment

Question 39

Neurons and the Environment

Answer 39

Some neurons become tuned to respond best to things that occur regularly in the environment that we commonly experience, potentially as a result of natural selection but also through learning

Question 40

experience-dependent plasticity

Answer 40

a mechanism that causes an organism's neurons to develop so they respond best to the type of stimulation to which the organism has been exposed. Ex: if an animal is reared in a particular environment, neurons in the animal's brain change so that they become tuned to respond more strongly to specific aspects of that environment (kittens in environment of verticals)

Question 41

Movement and perception

Answer 41

movement facilitates perception by helping us perceive things in our environment more accurately than static, still images. As you move around an object you get more information about it and can recover what created that percept

Question 42

The interaction of perception and action

Answer 42

Our actions within or upon the environment around us involve a constant stream of updating perceptions and recognition of very subtle changes. Ex: picking up a coffee cup

Question 43

Sticky Mittens experiment

Answer 43

Visual development may be related in important ways to manual exploration. Some aspects of visual development may be accelerated by enhancing infant's ability to manually explore objects with sticky mittens. We build the representations that we use for these internal processes from our interactions with the environment