What is Cognitive Science?

1
What is Cognitive Science?

• is the interdisciplinary study of mind and
  intelligence, embracing philosophy, psychology,
  artificial intelligence, neuroscience,
  linguistics, and anthropology

(Stanford Encyclopedia of Philosophy) http//plato
.stanford.edu/entries/cognitive-science/
2
Practical Value

• Education
• Intelligent tutoring systems
• Automatically grading exams
• Legal
• Distinguishing between true and false memories
• Evaluating line-ups
• Sales
• Understanding beliefs and desires
• Information technology
• Search engines
• Building intelligent systems
• Cognitive scientists might have some things to
  say about these issues.

3
Most cognitive scientists are cognitive
psychologists, computer scientists, or cognitive
neuroscientists
(from Schunn et al. 2005)
4
Understanding
Computation

To understand how
Computer Science/
the brain works
Artificial
I
ntelligence


Neuroscience

Interdisciplinary
study of intelligent behavior
To understand
For behavioral data in
Cognitive
limits

of theories

various tasks mental representations and
processes
Science

Philosophy

Cognitive Psychology
To understand

Linguistics

structure of
language


We will focus mostly on insights from Cognitive
Psychology
5
Areas of Study

• Cognitive psychology/science is about studying
  internal processes that are often unobservable,
  e.g.
• Perception, Attention, Memory, Visual Imagery,
  Language, Concept Learning, Reasoning
• Need converging evidence from different
  perspectives to really understand cognitive
  processes

?
6
Levels of Analysis

• Implementational
• Where does mental activity take place in the
  brain?
• How is processing actually done with neural
  activity?
• Algorithmic
• What is the abstract representation for input and
  output?
• What stages are used to process information?
• (Information processing level)
• Computational
• Why does the algorithm work well?
• What is the goal or purpose of the computation?

(Marr, 1982)
7
Levels of Analysis Example
8
Cognitive Neuroscience

• the study of the relation between cognitive
  processes and brain activities
• Potential to measure some hidden processes that
  are part of cognitive theories (e.g. memory
  activation, attention, insight)
• Measuring when and where activity is happening.
  Different techniques have different strengths
  tradeoff between spatial and temporal resolution

9
Information Processing

• Information processing models resemble processing
  in computers made cognitive psychology popular
• Idea is that information is processed in a number
  of stages
• The major goal of information processing research
  is to
• identify those processes
• identify how information is represented

10
Types of Processing

• Bottom-up processing
• Top-down processing
• Parallel processing
• Serial processing

11
An early version of the information-processing
approach? purely bottom up or stimulus-driven
12
A Demonstration of Top-Down Processing
13
Top-down processing perception affected by
knowledge of world
Why do we seem to have a fairly robust
interpretation of which shapes are concave and
convex when the perceptual information is
perfectly ambiguous? -gt perception affected by
knowledge
(Kleffner Ramachandran, 92)
14
Top down processing perception affected by memory

• First time, sine wave speech sounds
  incomprehensible (to most)
• After hearing the natural utterance, perception
  of sine-wave speech seems to be quite different

http//psiexp.ss.uci.edu/research/teachingP140C/de
mos/sinewavespeech.aif
"The steady drip is worse than a drenching rain."
http//psiexp.ss.uci.edu/research/teachingP140C/de
mos/naturalutterance.aif
(for more info http//www.haskins.yale.edu/haskin
s/MISC/SWS/SWS.html)
15
Sound Induced Illusory Flashes

• Example of parallel and interactive processing
  visual perception affected by auditory perception
  
• http//www.cns.atr.jp/kmtn/soundInducedIllusoryFl
  ash2/

16
Top-down processingLater stages of processing
affect earlier stages? can explain effects of
Knowledge, memory, expectations and context
17
Parallel vs. Serial Processing

• To illustrate the difficulty of distinguishing
  between serial and parallel processing, consider
  the Sternberg task
• Goal what steps are involved in comparing
  information to memory? How long do these steps
  take?
• Task
• give subjects memory sets. E.g. 3 9 7
• Probe memory with targets and foil digits 9
  yes, 6no. Measure reaction time.
• Vary the size of these memory sets

18
Typical Sternberg Results

• Plot reaction time as function of memory set size
  and type of trial (targets/foils)
• What are the implications of seeing a linear
  increase in reaction time as a function of memory
  set?

19
A serial information processing model for
Sternberg task
Make Decision
Is it a 7?
Perceive Stimulus
Is it a 3?
Is it a 9?
yes
9
This serial information processing model predicts
a linear increase
20
A parallel information processing model for
Sternberg task
Is it a 3?
Perceive Stimulus
9
Make Decision
Is it a 9?
yes
Is it a 7?
This parallel information processing model also
predicts a linear increase
21
Identifiability

• Sometimes, behavioral results do not allow
  processes and representations to be uniquely
  identified (e.g. Sternberg task)
• Identifiability refers to the ability to specify
  the correct combination of representations and
  processes used to accomplish a task

22
How can we tell models/theories apart?

• Need converging evidence to tell theories apart
• More behavioral data
• Data from cognitive neuroscience
• Data from neuropsychology

23
Note

• Please read book
• to review major brain structures and their
  functions
• to review brain imaging techniques
• See also additional PowerPoint slides available
  on class website