perceiving objects

Question 1

detecting features

Answer 1

• look at a collection feautures
• it is stimulus driven/bottom up
• using prior knowledge and expectations

Question 2

interpreting input

Answer 2

• determine from selections that may be ambigous
• if it was just from stimulus would see lines and circles
• brain based on expectations fills in the gaps

Question 3

gestalt principles

Answer 3

• german word form or apperance
• concerned with how perceptual organisation is achieved
• describe how we seperate and link (or parse) into individual objects

Question 4

similarity

Answer 4

group together objects that resemble each other

Question 5

proximity

Answer 5

closer objects are to each other more likely we are to group them together

Question 6

good countinuation

Answer 6

prefer to organise objects where contours continue smoothly

Question 7

closure

Answer 7

bias toward percieving closed objects rather than incomplete ones

Question 8

simplicity

Answer 8

interpret object in simplest way possible

Question 9

figure-ground segregation

Answer 9

• separating an object from its background
• pair of faces or vase
• cube illusion

Question 10

is it innate

Answer 10

• healthy controls=identified regions containing familiar configuration more than novel
• amnesia = no difference
• figure ground perception relies on past experience/learning

Question 11

strengths of gestalt principles

Answer 11

• focuses in fundamental issues
• simplicity
• principles applicable to complex images

Question 12

weaknesses of gestalt principles

Answer 12

• deemphasised importance of past experience
• provide descriptions (not explanations) of perceptual phenomena
• principles of perceptual organisation based on 2D drawings

Question 13

feature detection theories

Answer 13

• a simple pattern, fragment or component
• appears in combination with other features across a variety of stimuli
• object recognition first involves identifying ‘building- block’ features

Question 14

visual search

Answer 14

• indicate as quickly as you can whether a particular target is present
• differs from the others e.g. vertical line in array of horizontal

Question 15

feature nets bottom up

Answer 15

hierarchy of how we identify an object or group to create a coherent whole

Question 16

geometric ions

Answer 16

• recognition by components (RBC) theory
• all objects reduced to geons
• out of 3d shapes you can create an object

Question 17

recognition by components

Answer 17

• perceiving components is the first major step in object recognition
• object recognition is a joint effort between two processes

Question 18

non recoverable objects

Answer 18

• vertices (two lines meet) missing
• cannot or take longer to recognise object

Question 19

recoverable objects

Answer 19

• segments of smooth, continous edges missing
• easy to fill in missing parts and recognise object

Question 20

weaknessses of theories

Answer 20

• tied to bottom up processing
• some evidence contradicts the feature first aspect of the model. whole object can be percieved rapidly or automaticly
• embeded cognition, perception of objects influenced by our expectation of how we will interact with those objects

Question 21

perceptual consistency

Answer 21

• we percieve the constant properties of objects in the world, despite sensory info changing
• essential aspect of percieving objects, needed to perceive what something is

Question 22

size constancy

Answer 22

correctly perceive size on objects, despite changes in size created by viewing distance

Question 23

shape constancy

Answer 23

correctly percieves shapes of objects despite viewing angle e.g. door

Question 24

colour constancy

Answer 24

correctly perceive same colour of an object despite changes in wavelengths

Question 25

object comparison

Answer 25

- how do we achieve perceptual constancy? - compare target object with those in background - role of interpretation - the monster illusion (misperception of size)

Question 26

binocular cues

Answer 26

- each eye has a different view of the world (stereopsis) - difference = binocular disparity (3d glasses)

Question 27

oculomotor cues

Answer 27

- convergence: eyes turn inwards when we focus on close objects - accomodation: shape of lenses in eyes changes shape depending on object distance

Question 28

monocular cues (pictoral)

Answer 28

- interposition/occulsion- blocking of our view of one object by another - linear perspective- parrallel lines seem to converge as they get farther from the viewer - texture gradient- as surface gets farther away its texture appears finer and smoother

Question 29

motion cues

Answer 29

- motion parallax- nearby objects move more rapidly - optic flow- as we approach object larger it becomes

Question 30

agnosia

Answer 30

- failure to recognize objects - deficit caused by brain damage

Question 31

apperceptive agnosia

Answer 31

- ability to percieve feautures - unable to group them together - damage to posterior rear regions of right hemisphere

Question 32

associative agnosia

Answer 32

- able to group or combine features - cannot associate features with stored knowledge of object identity - damage to temporal and occiptal lobes in both hemispheres

Question 33

implications

Answer 33

1. detecting this feature in a visual stimulus in a seperate or later process from sensation 2. detecting visual features critical in constructing whole object 3. seperate step in connecting object with it’s meaning and name

Question 34

face recognition

Answer 34

- differs in important ways from other forms of object recogniton - involves holistic processing

Question 35

holistic processing

Answer 35

involves integrating info from an entire object