Cognitive Science Modules 7-12

all the key terms for these modules for the final exam :)

Chomsky’s hierarchy

a containment hierarchy of classes of formal grammars; in the case of languages, it spans from finite to context-free

Poverty of the Stimulus

* unknown that the stimulus exposed to learner has a relation to linguistic behavior
* children lack sufficient input, negative evidence, and correction
* against B.F. Skinner’s verbal behavior

Hierarchical structure in language

a way that we mentally represent a sentence; linear relationship is bad as it does not give a clear meaning

Phonology

study of sounds

Morphology

study of words and how they are formed

Syntax

the study of arrangement of words and phrases

semantics

study of meaning and relationships of words

syllable density

how many sounds can you put in a row to form one syllable

What are 7 essential features of human language?

1. mode
2. meaning
3. arbitrariness
4. discreteness
5. displacement
6. productivity
7. cultural transmission

mode

expression in speech/sign

meaning

significance of words

arbitrariness

words do not sound like how they are (ex: “dog” does not sound like an actual dog)

discreteness

ability to think about something that was not immediate

productivity

produce new sentences

cultural transmission

learn language from experience

competence

knowing what to say → subconscious knowledge of language

* contains mental grammar
* native speakers who have perfect knowledge of language = perfect of this

performance

being able to produce those words → coordinating linguistic knowledge and other cognitive systems

language

set of computations our mind does; very structured & principled + connectionist networks are not good at this

Eric Lennenberg’s biologically controlled behaviors

* behavior emerges before necessary
* emergence is not triggered by external events
* direct teaching and intensive practice little effort
* critical period is where we acquire biological behaviors (i.e. language)

Early attempt to define meaning was:

truth conditionals (ex: snow is white if and only if snow is white)

Force vs. Content

* a way to define meaning
* Assertic force: “Snow is white”
* Interrogative force: “Is snow white?”
* Content = meaning = the same

Sense vs. Reference

* a way to define meaning
* sense: mental, conceptual representation of the word’s meaning
* reference: the thing/object the word describes

Externalism vs. Internalism

* the best way we currently define meaning
* externalism: meaning is dependent on the objects in the real world
* internalism: meaning is dependent on the representations in your head of that word/sentence

frontal lobe

emotion, decision making and organization

prefrontal cortex

short-term memory and ability to pay attention

temporal lobe

long-term memory, language, comprehension and identifying objects

brainstem

body basics (i.e. heart rate and breathing); central to alertness and ability to sleep

cerebellum

skill memory and movement coordination

occipital lobe

processing visual information

parietal lobe

processing sensory information + spatial awareness

somatosensory cortex

responsible for sensations

motor cortex

responsible for movement and coordination

corpus collasum

a bundle of neural fibers that connects the two hemispheres

gyrus

bumps in brain

sulcus

crevices in brain

Why is the brain wrinkly?

more surface area → cortex contains more mental computations

contralateral organization

* the way our brain is organized
* the left hemisphere controls the right side of the body
* the right hemisphere controls the left side of the body

right ear advantage

right ear → auditory cortex in right hemisphere → language area in left hemisphere

left ear → auditory cortex in right → language area in left hemisphere (much slower)

split-brain patients

* corpus collasum cut → connections between left and right hemispheres lost
* if a word is written on the right side in field of vision, patient is able to say the word
* left hemisphere dominant in verbal processing
* if a word is written on the left side in field of vision, patient is not able to say the word
* right hemisphere cannot share information with the left hemisphere
* however, patient can draw it
* significance
* left and right hemispheres have specialized tasks
* it is possible that we might have two separate consciousness

Neuroimaging (list them)

* TMS
* EEG
* MRI (fMRI)
* PET
* fNIRS
* MEG

What can neuroimaging tell us about? What can it not tell us about?

It can tell us:

* cognitive process that correlates with the brain activity

It cannot tell us:

* anything about cognitive processes
* if brain regions are necessary for these cognitive processes
* how the brain supports these cognitive processes

Hemodynamics

* measures blood flow in brain
* energy (blood flow) to power brain activity → blood delivers food for neuron firing
* significant as blood flow only travels to the active regions in the brain for a certain cognitive task
* MRI, fMRI, PET, fNIRS

Electrophysiology

* measures electrical signals from neurons firing
* EEG, MEG

What do EEG and MEG tell us about the brain?

* when things happen in the brain
* can tell us about the algorithms happening in the brain
* can give you a timeline of what order the operations/computations take place (ex: when the brain region is interpreting a certain word)
* answer questions in Marr’s 3 levels of analysis
* answer questions about mental representations
* this is all due to good temporal resolution

What does fMRI, MRI, PET, and fNIRS tell us about the brain?

* where things are happening in the brain
* we need to know the computations for functional specialization

functional specialization

a specific part of the brain does a specific computation

TMS

* switches brain part that converts words into symbols
* usually to treat depression/anxiety

EEG

* implants electrodes onto brain’s cortical surface or head
* detect/investigate epilepsy
* convert processes in real time
* stages of processing
* mental representations - how activity can be encoded in the algorithmic level
* active potential (within a neuron: 1 msec) and postsynaptic potential (between neurons and slower: 10s/100msec)

MRI

uses magnetic field or examine organs, tissue and skeletal system

fMRI

looks at the function of the brain

PET

* uses positrons to evaluate function of organs and detect cancer
* injects radioactive tracer
* scanner detects radioactive decay
* measures regional cerebral blood flow (rCBF)
* spatial resolution: 4mm
* temporal resolution: 30-40 secs; very **bad**

fNIRS

* uses infrared lasers through a person’s head
* reconstructs amount of blood flow by reconstructing the strength of the laser

MEG

* similar to EEG but instead of electrical it uses the magnetic domain
* detect/investigate epilepsy

ECG

* sensors attached to skin that detects electrical signals produced by heartbeats
* check heart’s rhythm and electrical activity

Structural vs. Functional MRI

* represents activity in brain particular to specific stimulus
* calculates the average of all activity recorded for that specific stimulus
* uses BOLD (blood oxygenated level dependent) signal
* no required radioactive tracers
* spatial resolution: 3-6mm
* temporal resolution: 3-6 sec

invasiveness

how easily can the machine integrate in the brain (poor would mean you would have to cut open the head)

spatial resolution

refers to pixel density

temporal resolution

* margin of error time
* how long you have to wait until you get the data

implicit learning

* cue-based
* effortless
* unconscious
* gradual
* no feedback
* positive examples only

explicit learning

* rule-based
* effortful
* conscious
* abrupt (info received and learned immediately)
* feedback
* both positive and negative examples

What does explicit vs. implicit learning experiments show?

* different cognitive processes are used in implicit vs. explicit learning
* explicit is better for doing things quickly: if you tell people what they are supposed to learn it, they learn!

event-related potentials (ERP)

* measured brain response that is the direct result of a specific sensory, cognitive or motor event that occurred
* ex: I take my coffee with cream and SOCKS
* this triggered a bump in ERP activity

memory systems

**incoming info** → **sensory** (not attended to = forgotten) → **selective** **attention** (what are we focusing on)→ **working** (not attended to = forgotten) → **successfully coded for storage in long-term memory due to rehearsal buffer** → **long-term**

sensory memory

* a mental representation of how the environment events involving the senses
* large capacity
* short duration
* two types we know of well: iconic and echoic

iconic memory

* type of sensory memory
* visual memory
* 250-300ms duration

echoic memory

* type of sensory memory
* auditory
* lasts for a few seconds
* probably due to the fact that hearing something (i.e. a song) cannot be heard in one instant (unlike iconic)

working memory

* aka short-term memory
* longer duration than sensory
* more limited storage capacity
* functions: manipulates information and focuses attention
* capacity: 7 recognizable chunks (+/- 2)

recoding

occurs when representations of individual items are chunked together into another representation and is assigned a label

decay

memory fades due to passage of time

rehearsal

revisiting current contents of working memory with the aim of maintaining or improving memorability

2 types: maintenance and elaborative

maintenance rehearsal

repetition, either linguistically or refreshing images

elaborative rehearsal

connect to other memories already encoded in long-term memory

What goes into working from sensory?

anything that is salient! (most important/noticeable)

mental operations we do in memory

* constructive operations
* transformations
* decision processes

constructive operations

building a sentence representation

transformations

mental rotations (scan, zoom)

decision processes

identification, comparison

memory

active system that receives, stores, alters and recovers/retrieves information

encoding

converting information into usable form (ex: coding colors in hex code)

storage

holding information in memory for later use

retrieval

taking memories out of storage

mental search algorithms

* serial processing
* parallel processing

serial processing

* mentally lining up numbers in order and finding a particular one
* as set size increases, search time increases

parallel processing

* looking all at the numbers at once to find a particular number
* as set size increases, search time is constant

self-terminating search

* once you find a particular item in series you would stop
* as position of target is further along in series, search time increases

exhaustive search

* you search all the items in the series
* may be inefficient but sometimes necessary (ex: finding all the bugs in your basement)
* as position of target is further along in series, search time stays constant

binary search

order numbers in set

positive vs. negative trials

* positive indicates number/item was found in series
* negative indicates number/item was not found in series

parallel search (trials)

as set size increases, reaction time is constant

serial search (trials)

as set size increases, reaction time increases

serial search, exhaustive

the rate of increase is the same in both positive and negative trials

serial self-terminating search

the rate of increase is in both but is greater in negative trials

long-term memory types

* LTM
* explicit
* episodic → imagery
* semantic → factual info
* implicit (not easy to describe)
* procedural → how to do something

long-term memory concepts

* constructive processing
* pseudo-memory
* network model
* redintegration

constructive processing

reorganizing/updating long-term memories on basis of logic, reasoning or adding new information

pseudo-memory

false memories that are believed to be true/accurate

network model

view structure of LTM as an organizational system of linked info (ex: “mosquito” → “bite”)

redintegration

one memory triggers another

memory in the brain (implementational level)

* sensory info enters the brain
* info is encoded
* hippocampus integrates representation
* representations stored in the cortex

Is memory stored in discrete locations?

* memory is NOT stored in discrete locations
* distributed representation
* each node (think connectionism) contains parts of a memory
* not stored in a discrete location