Chapter 5: Perceiving Objects and Scenes

Name the 7 principles

1. Good continuation 2. Pragnanz 3. Similarity 4. Proximity 5. Common Fate 6. Common Region 7. Uniform connectedness

What are physical and semantic regularities in the environment?

1. regularly occurring physical properties of the environment 2. the characteristics associated with activities that are common in different types of scenes

Describe what happens when objects are hidden or blurred

1. we can still identify objects 2. we can use our knowledge of environment to determine this

Define Principle of Common Region

Elements that are within the same region of space apear to be grouped together

What did Zeidman experiment show?

that PPA/PHC is activated by patterns that create impression of 3D space but contain no objects

Define Perceptual Segregation

1. Another Gestalt approach 2. Perceptual organization in which one object is seen as separate from other objects 3. Includes figure-ground segregation

Describe the Gibson and Peterson Experiment that argues against above

1. Figure can be perceived as a. standing woman (black part) b. less meaningful shape (white part) 3. they presented stimuli for a fraction of a second and asked observer which region they see figure 4. RESULTS: they were most likely to say woman was figure

Describe the Wertheimer example on how built-in principles can override experience

1. Most people see the MW display as W itting on top of an M moslty because of our past experience with those letters 2. When the letters are arranged directly upright, we see two uprights and a pattern in between them created by principle of good continuation - our perception overrides the effects of past experience - SO past experience plays a minor role in perception

What areas process what kinds of info associated with faces in the brain?

1. Occipital cortex: initial processing of face info 2. FFA: identification of faces 3. Amygdala: emotional aspects of faces/reactions to facial expressions 4. Superior temporal sulcus: evaluation of where a person is looking 5. Frontal cortex: evaluation of a face's attractiveness

What is the Gestalt approach to Perceptual grouping

1. Structuralism: the approach to psychology that postulated that perceptions result from the summation of many elementary sensations a. came before the Gestalt approach from Wundgt b. saw sensations as as analogous to atoms of chem - just like atoms, sensations combine to create complex perceptions - sensations = simple - perception = complex 3. Gestalt psychologists reject the idea that perception is formed by adding up sensations

What is 1/2 image-based factors that determine which area is the figure?

1. The first one is that areas in lower field of view are more likely to be perceived as figure

Define persistence of vision Define visual masking stimulus

1. a phenomenon in which perception of any stimulus persists for about 250ms after the stimulus is physically terminated 2. a visual pattern that when presented immediately after a visual stimulus, decrease a person's ability to perceive the stimulus - this stops the persistence of vision and therefore limits the effective duration of the stimulus

define apparent movement

1. an illusion of movement that occurs when two objects separated in space are presented rapidly, one after another, separated by a brief time interval

How did Frank Tong use binocular rivalry to connect perception and neural responding?

1. by presenting picture of a person's face to one eye and a picture of a house to the other eye 2. had ppl view the pictures through coloured glasses which caused face to be presented to left eye and house to right 3. because each image received a different image, BR occurred - while images remained same on retina, observers perceived just the face or just the house 4. Used fMRI to measure activity in PPA and FFA RESULTS: when they were perceiving face FFA activity increase and PPA decreased

Define Illusory contours What does this argue against? Why can't sensations explain IC?

1. contour that is perceived even though it is not present in the physical stimulus 2. argues against sensation and that the whole is different than the sum of its parts 3. because there aren't any sensations along contours

What 5 global image features enable us to perceive the gist of image so fast?

1. degree of naturalness 2. degree of openness 3. degree of roughness 4. degree of expansion 5. degree of color

What are some properties of GIF?

1. dont depend on time consuming processes 2. they contain info about scene's structure and spatial layout 3. GIF help explain not only how we can perceiev gist of scene but that our past experincs play a role in determining our perceptions

Corresponding to that, what is the Vecera Experiment?

1. flashed stimuli for 150ms and determined which area was seen as figure. The red or green? 2. Results: In upper-lower displays, they were more likely to perceive lower area as figure, but for left-right displays they only showed small preference for left region 3. CONCLUSION: there is ONLY definite preference for seeing objects lower in display as figure

What did Gibson and Peterson's second demonstration illustrate? Describe it

1. how meaning can influence perceptual organization on a larger time scale 2. Finding faces in landscape - initially it's hard to find faces - they change perception from rocks in the stream to faces due to our familiarity with faces - you'll never not see the faces the next time you look

Describe what happens when we see objects from different viewpoints

1. image is continuously changing 2. viewpoint invariance: the condition in which object properties don't change when viewed from different angles. Responsible for our ability to recognize objects when viewed from different angles 3. difficult task for computers which means the process of perception is more COMPLEX than it seems

describe wethreimer's 2 conclusions of apparent movement

1. it can't be explained by sensations because there is nothing in the dark between the flashing lights 2. the whole is different than the sum of it's parts

How did they study figure-ground?

1. one way was considering reversible figure-ground: a figure ground pattern that perceptually reverses as it's viewed, so figure become ground and vice-versa

Define Principle of good continuation

1. 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 2. objects that are partially covered by others are seen as continuing behind the covered object ex: ROPE

Describe the Stephen Palmer experiment on how scene schema can influence perception

1. presented a context scene and then flashed a target picture (loaf of brad, mail box, wheel) 2. when asked people to identify object in target pic they did correctly 80% of the time as it fit the scene

Describe the Lei Fei-Fei experiment

1. presented pics of scenes for different exposure times. 2. Used masking procedure to be sure observers saw pics for desired duration 3. participants asked to describe what they saw RESULTS: overall gist perceived first followed by perception of detail

Define Gestalt Psychologists principles of perceptual organization

1. principles that describe how elements in a scene become grouped together. - determines how elements in scene can be grouped together - predict what we will perceive based on what actually happens in the environment

define Epsein's Spatial layout hyothesis

1. proposes that that the PPA/PHC responds to the surface geometry or geometric layout of a scene 2. this proposal is based partially on fact that scenes cause larger responses than buildings

According to Gestalt, what is one of the first things that happens in perceptual process when organizing?

1. segregation of figure from ground

Describe the Mary Potter Experiment on how long it takes people to perceive gist of scene

1. showed people a target picture and asked them to indicate if they saw that picture as they viewed sequence of 16 rapid pics 2. they could do it with almost 100% accuracy even if pics only flashed for 1/4 second

The Role of Perceptual Principles and Experience in Determining which area is figure - what did GP's believe?

1. that although experience can effect perception, built in principles can override experience

What is 2/2 image-based factors that determine which area is the figure? What is the Peterson Example of this?

1. that figures are more likely to be perceived on the convex side of the border 2. Peterson presented bulging figure displays and asked people to indicate whether a red square was on ot off it 3. RESULT: dark regions were considered figure 89% of the time 4. They went further presenting same figure with fewer components to decrease likelihood that convex region would be seen as a figure 4. RESULT: seen as figure 58% of the time CONCLUSION: to understand how segregation occurs we need to go beyond simply identifying factors like convexity

Describe how the stimulus on receptor is ambiguous

1. the perceptual system task is to determine objects responsible for particular image on retina 2. inverse projection problem: the idea that a particular image on the retina could have been caused by an infinite number of different objects. This means that the retinal image does not unambiguously specify a stimulus 3. Fig 5.5: retinal image created a rectangular page could have been created by other objects at different distances = image on retina is ambigious - may have erroneous perception

what are the components that create apparent movement

1. there are 3 components that create apparent movement a. light flashes b. period of darkness c. second image flashes - we don't see the darkness because our perceptual system adds perception of an image moving during darkness

Describe Maguire's proposal that PPA/PHC is activated by any stimulus that results in a sense of 3D space even if there is no scene

1. they determined the connection between 3d space and PPA/PHC activity by creating a list of 399 everyday objects that are found in indoor environment and had each person rate each object as a. space defining b. space ambiguous RESULTS: the SD objects caused more activity in the PPA/PHC than SA SO PPA is activated not only by fill scenes, but by objects that create a sense of surroundings

why were they most likely to say the figure was a woman?

1. they recognize the black area as a familiar object

Define Bayesian inference

1. when our estimate of the probability of an outcome is determined by prior probability/ prior OR the extent to which the available evidence in consistent with the outcome

Define the likelihood principle of Helmholtz

1.we perceive the object that is most likely to have caused the pattern of stimuli we have received

Define Principle of Uniform Connectedness

A connected region of the same visual properties, such as lightness, color texture, or motion is perceived as a single unit

Define the Principle of Pragnanz

ALSO called principle of good figure/simplicity 1. Every stimulus pattern is seen in such a way that the resulting structure is as simple as possible ex: ** OLYMPIC SYMBOL - we see it as a display of five circles and not as a larger number of more complicated shapes

What is the second method to analyze patterns of voxel activation?

Semantic encoding: a method for analyzing patterns of voxel activation recorded from the visual areas of an observer's brain, based on the relationship between voxel activation and the meaning/category of a scene

Define Principle of Similarity

Similar things appear to be grouped together

What is the first method to analyze patterns of voxel activation?

Structural encoding: a method for analyzing the patterns of voxel activation recorded from visual areas of an observer's brain based on the relationship between voxel activation and structural characteristics of a scene like lines, shapes textures

Define Principle of Proximity/Nearness

Thing that are near each other appear to be grouped together

Define Principle of Common Fate

Things that are moving in the same direction appear to be grouped together ex: flock of birds

What are the properties of figure ground?

a. figure is more thinglike and more memorable than ground b. figure is seen as being in front of ground c. near borders it shares with figure, ground is seen as uniform material d. the border separating figure from ground appears to belong to a figure

What is a modern example of apparent movement?

electronic signs

What happens to incoming stimulation during perceptual organization?

it is organized into coherent units (objects) - involves grouping and segregation

define unconscious inference of Helmholtz

some of our perceptions are the result of unconscious assumptions that we make about the environment

Define figure-ground segregation

the perceptual separation of an object from it's background

define binocular rivalry

when the observer perceives either the left-eye image or right, but not both at the same time

define border ownership

when two areas share a border, the border is usually perceived as belong to the figure