Sensation/Perception and Object Recognition

Question 1

Why is vision different from our other senses?

Answer 1

A lot of real estate in the brain related to visual processing

vision allows us to process and evaluate our environments

Question 2

Cornea

Answer 2

the eye’s outermost layer. It is the tran

Question 3

Iris

Answer 3

a thin circular structure in the eye, responsible fro controlling the diameter and size of the pupil and thus the amount of light reaching the retina (gives the eye its color)

Question 4

Lens

Answer 4

is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina

Question 5

Fovea

Answer 5

Specialized for high-resolution visual information

Question 6

Retina

Answer 6

10 densely packed layers of neurons

the deepest layer is made up of millions of photoreceptors

Question 7

Optic Nerve

Answer 7

transmits impulses to the brain from the retina at the back of the eye

Question 8

photoreceptors

Answer 8

rods and cones

Question 9

Rods

Answer 9

contains the photopigment rhodopsin which is destabilized by low levels of light (night vision/black and blues)

Question 10

Cones

Answer 10

contain photoreceptor photopsin which requires more intense levels of light (daytime/colors)

Question 11

Ganglion Cells

Answer 11

the output layer of the retina, their axons form a bundle known as the optic nerve and that carries information to the brain

Question 12

Connection to the CNS

Answer 12

the rods and cones are connected to bipolar neurons that then synapese with ganglion cells –> axons of ganglion cells form the optic nerve –> optic chiasm –> 90% of the axons go to the retinogeniculate pathway (Lateral geniculate nucleus of thalamus) and 10% fots to the pulvinar nucleus of the thalamus and superior colliculus of the midbrain

Question 13

Geniculocortical Pathway

Answer 13

Terminates in the primary visual cortex (V1/striate cortex) of the occipital lobe

Question 14

Retinogeniculate pathway

Answer 14

lateral geniculate nucleus of the thalamus

contains more than 90% of the axons from the optic nerve

Question 15

Pulvinar Nucleus & Superior Colliculus

Answer 15

play a role in visual attention

other 10% of the axons

Question 16

Retinotopic Maps

Answer 16

Neurons in the visual system represent space in an orderly manner

Visual neurons only respond when a stimulus is presented in a specific region of space (that neuron’s “receptive field”)

Question 17

Hubel and Wiesel

Answer 17

Individual neurons respond to very specific stimuli

Question 18

Where does visual information go once it’s processed by V1?

Answer 18

to many different extrastriate visual areas (30+)

Question 19

Sensation

Answer 19

Early processing that goes on

Most clearly linked to V1

Question 20

Perception

Answer 20

begins with a stimulus from the environment, which stimulates one of the sense organs –> the input is transduced into neural activity and sent to the brain for processing

Most closely linked to extrastriate cortex

Question 21

Enigma Pattern

Answer 21

illusory motion

when human view this pattern while undergoing an fMRI scan, there is activation in the MT (responsible for motion)

Question 22

Object recognition

Answer 22

result of sensation, perception and memory

1. Sensation is different from perception and recognition
2. Our perception is of unified objects
3. Perceptual capabilites are extremely flexible and robust (object constancy)
4. Perception and memory are intimately interwoven

Question 23

Patient G.S.

Answer 23

patient that proves that sensation is different from perception and recognition

his sensation was completely intact but have perception and object recognition failures

Shown a photo of a combination lock, started making a rotary motion with his hands but couldn’t make the leap from the sensation to what the object really was (guessed it was a telephone)

Question 24

What vs Where

Answer 24

Output from V1 is contained in two major fiber bundles called fasciuli (purple bundles)

Question 25

Superior Longitudinal Fasciculus

Answer 25

(dorsal stream/occipitoparietal) Takes a dorsal path, terminating mostly in posterior regions of the parietal lobe Indicates where information is in space

Question 26

Inferior Longitudinal Fasciculus

Answer 26

(ventral stream/occipitotemporal) takes a ventral path, terminating mostly in the temporal lobe what an object is, object perception and recognition

Question 27

Neuropsychological support for What vs Where

Answer 27

animal evidence:double dissociation Bilateral lesion of the temporal lobe leads to a behavioral deficit in a task that requires the discrimination of objects vs bilater lesion of the parietal lobe leads to a behavior deficit in a task that requires the discrimination of locations (landmarks)

Question 28

Patient D.F

Answer 28

had lesion in ventral stream in the perception condition: she failed to correctly orient her hand to match the orientation of the card to that of the slot In the action condition: she correctly inserted the card when asked to do so (failing at the recognition of the object in front of her) Perhaps her dorsal stream wasn't damaged and also helps guide interactions with objects, maybe better labeled "how"

Question 29

Neuronal-Based Evidence for What vs Where

Answer 29

Dorsal Stream: The receptive fields of neurons encompass not only the fovea but also non-foveal regions vs Ventral Stream: Receptive fields of the neurons always encompass the fovea

Question 30

Neuroimaging (PET) Evidence for What vs Where

Answer 30

Subject views image A Object Task/ventral: Subject is asked if the three objects are the same as the screen they viewed Spatial Task/dorsal: Subject is asked if the threeobjects are in the same positions as the screen they viewed

Question 31

Two different theories for object recognition

Answer 31

View Dependent View Invariant

Question 32

View-Dependent Recognition

Answer 32

We have a stored representation of object in memory When we see an object, we "match" it to our stored representation

Question 33

Evidence for View-Dependent Recognition

Answer 33

Reaction time for naming an object is shortest when the view gives the most information about it

Question 34

Advantages and Disadvantages of View-Dependent

Answer 34

Advantages: reaction time data shows that the way that we view an image matters with identification Disadvantages: When viewing a novel object, does that mean you cannot accurately label it? Assumes heavy burden on memory because have to store representations

Question 35

View Invariant Recognition

Answer 35

Perceptual system extracts information about the components of an object and the relationship between those components critical properties of an object stay independent of viewpoint

Question 36

Evidence for View Invariant Recognition

Answer 36

Reputation suppression effect: the more you view a stimulus/object, the fewer neurons fire in response to the object

Question 37

Shape Encoding

Answer 37

simple features can be combined into edges corners and intersections, which can then be grouped into parts and then grouped into objects

Question 38

Two different theories of encoding objects

Answer 38

Hierarchical Representation Ensemble Coding

Question 39

What part of the brain is critical for shape and object recognition

Answer 39

Lateral Occipital Cortex

Question 40

Grandmother Cells/ Hierarchical Representationsof Objects

Answer 40

The final percept of an object is coded by a single cell aka "grandmother" Hallie Berry Study (individual electrodes implanted in cortex, neurons would fire specifically to images of hallie berry)

Question 41

Ensemble Coding of Objects

Answer 41

Cells coding for different features of an object or face work together to permit perception and recognition

Question 42

Agnosia

Answer 42

"Without knowledge" Types: Visual, Appericeptive, Integrative, Associative and Prosopagnosia

Question 43

Visual Agnosia

Answer 43

Object recognition problems eventough visual information continues to be registered at the cortical level Sensation is still intact (dont know what keys are when visually looking at it but when holding them in her hand she knows what it is) A perceptual problem, not a memory problem.

Question 44

Appericeptive

Answer 44

Intact Vision: acuity, brightness discrimination, color vision Deficits: abnormal shape perceptions, integration of spatial information (esp. for right sided lesions) The right hemisphere is especially important in object recognition and therefore damage is usually in right hemisphere towards posterior in appericaptive agnosia patients

Question 45

Unusual Views test

Answer 45

Test for apperceptive agnosia patients would have trouble recognizing a chair from above

Question 46

Test for Appericeptive Agnosia

Answer 46

some patients would have trouble drawing a chair if missing contours Patients can draw a photo but not in typical order (cannot fully integrate it and copy it accurately)

Question 47

Associative Agnosia

Answer 47

Inability to understand or assign meaning to objects Subject can copy an image accurately but cannot tell you what it is The border of occipital and temporal lobes and bilaterally

Question 48

Matching by function Task

Answer 48

Question 49

Prosopagnosia

Answer 49

Impairment in face recognition Patients are still able to accurately recognize objects (though below normal) Can be congential or result from brain damage Generally involves the occipital and temporal lesions Fusiform gyrus (in ventral stream) --\> fusiform face area(FFA)

Question 50

Is there a specialized system for face processing?

Answer 50

prosopagnosia suggest so but this hypothesis must be approached cautiously because it is hard to find control objects that match faces in complexity

Question 51

Patient C.K.

Answer 51

Had severe object recognition deficits but could perceive faces with relatively little trouble

Question 52

Answer 52

we prefer to integrate all the parts of the face