Lecture 2- Levels of Analysis and Explanation

Question 0

Perception as an active process

Answer 0

start with an agent with some developmental history: how they develop a knowledge base

what if it wasn’t a human agent? what kind of agent: different types of sensors and uses that info differently

Question 1

human sensory systems can be best thought of as…

Answer 1

…actively engaging sensory stimuli

it’s an interaction with the environment, focusing your eyes on something: they’re always moving, you’re always changing your perspective a bit

Question 2

Environmental Stimulus

Answer 2

distal stimulus:

• ex: tree, object that you’re trying to detect
• it’s always at a distance
• try to orient towards it

some input will come from the d.s.

first step where things can go wrong: light going through the atmosphere, obscured by smoke

Question 3

Receptor Processes

Answer 3

• stimulus (light energy) transduced into electrical energy

- transduction: changing in the type of energy

Question 4

Neural Processing

Answer 4

happens at the local level and further on through the primary sensory cortex

Question 5

Consciously Perceive (detect) that there is a thing

Answer 5

detected the distal stimulus

may not know the nature of the thing, can’t catagorize

if we have enough we go from perceptoin to recognition (OH! it’s a chair)

with or without recognition you’re still going to act

Question 6

Perception vs. Recognition

Answer 6

you can have one without the other

example: indivual can describe an object in detail without being able to put it in a specific class: VISUAL FORM AGNOSIA where common objects cannot be recognize

Recognizing without Perceiving: Blind site: where people believe they are blind but under the right testing conditions they can recognize objects without consciously percieving it: different functions dissociated from one another: suggests that there are diff parts of the brain responsible for those functions (diff parts of the brain for perceptions and recognition)

Question 7

Visual form agnosia

Answer 7

you recognize someone but you can’t place how you know them

perception without recognition

Question 8

top-down processing

Answer 8

history biases you to interpret results in certain ways

experience literally makes you look at things differently

Ex: twins: one twin is an entomologist and one hates bugs: both detected and both attempted recognition but both had different sensory experiences: interact with the environmental stimulus differently

Question 9

bottom up processing

Answer 9

receptors excited based on input

with always interact with the top down processing = never one or the other, it’s both

Question 10

How do we measure effects at each state of the perceptual process? Where do we start?

Answer 10

define terms
framework
perception doesn’t happen at just one level, involves a lot, so our framework has to account for that =

Question 11

Measurment

Answer 11

assigning numbers to observable entities or events

problem: how to observe what’s going on in someone’s head? you can’t see it?

Question 12

Sensory qualia

Answer 12

the technical term for the experience in someone’s head, associated with some particular event

experience of a certain color, hearing a sound, detecting a taste

are all subjective

can’t be directly observed

Question 13

Theoretical constructs

Answer 13

we believe that unobservable entities (color perception) exist in some sense, but can’t be directly observed

Question 14

operational defintion

Answer 14

created for the internal theoretical construct

assigns observable behavior as a proxy

when we see it we can make an inference that come perception is being experienced

fundamental fact of science

when i measure that thing it tells me it’s there

Question 15

precision is theoretically limiting

Answer 15

what if your operational defintion is wrong?

- what if mri isn’t a good indicator of brain activity? you’ve been thinking about things the wrong way

Question 16

operational def.

Answer 16

observable act

pointing, speaking

Question 17

theoretical constructs

Answer 17

recognition and perception

Question 18

what is vision for? what is hearing for?

Answer 18

model of processing can’t help with that, assumes you know the problem

doesn’t tell you the problem itself

Question 19

Marr’s Level’s of Analysis *****

Answer 19

computational level

algorithmic level

implementation level

complementary and interact with each other

Question 20

david marr

Answer 20

first computational neuroscientist

computer scientist interested in computer vision

hippie

book: Vision

asked some basic questions trying to come up with computer vision systems

bigger question: what is the system trying to solve? what is vision doing for us?

Question 21

computational level

Answer 21

basic question: what problems does the system solve and why?

what does vision do? danger: color, motion, edges

Question 22

algorithmic level

Answer 22

if this system is trying to solve some problem (danger-threat level), how does it do that? what representations does it use?

goes through a serious of steps: looks through features that indicate threat

Question 23

implementation level

Answer 23

what’s happing in the brain?

is it neural tissue? in a computer system? how is being physically instantiated? how does it act? does it go through some steps on the algorithmic level to solve some problem on the computational level?

Question 24

what about when one of the different levels comes into conflict?

Answer 24

key to scientific progress, what you would look for is the most concurring evidence that all holds together = higher theory

Question 25

Proximal stimulus

Answer 25

• info bounced off of that object
• info as transmitted from the atmosphere that hits the eye
• how could it be different if we had a diff kind of eye? (camera lens, bird’s eye)
• always different from distal stimulus