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Organizational Notes. no study guide no review session not sufficient to just read book and glance at lecture material midterm/final is considered hard by some students questions will relate to both book and lecture material . What is Cognitive Science?.

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organizational notes
Organizational Notes
  • no study guide
  • no review session
  • not sufficient to just read book and glance at lecture material
  • midterm/final is considered hard by some students
  • questions will relate to both book and lecture material
what is cognitive science
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)

practical value
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.


Most cognitive scientists are cognitive psychologists, computer scientists, or cognitive neuroscientists

(from: Schunn et al. 2005)


Understanding Computation

Building computer models that learn from the environment

To understand how

Computer Science/

the brain works






study of intelligent


To understand

For behavioral data in



of theories

various tasks; mental representations and processes



Cognitive Psychology

To understand


structure of


We will focus mostly on insights from Cognitive Psychology

areas of study
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


levels of analysis
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?
    • (also known as information processing level)
  • Computational:
    • Why does the algorithm work well?
    • What is the goal or purpose of the computation?

(Marr, 1982)

cognitive neuroscience
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
information processing
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
types of processing
Types of Processing
  • Bottom-up processing
  • Top-down processing
  • Parallel processing
  • Serial processing

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? -> perception affected by knowledge

(Kleffner & Ramachandran, ’92)

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

Top down processing: perception affected by memory

"The steady drip is worse than a drenching rain."

(for more info:

sound induced illusory flashes
Sound Induced Illusory Flashes
  • Example of parallel and interactive processing:
    • processing of perceptual information in one modality is often affected by processing in another modality
  • Demo of sound induced illusory flashes:
    • For more information on this effect see:
    • note: demo might not work on your particular computer
    • Demo shows that visual perception affected by auditory perception
Top-down processingLater stages of processing affect earlier stages can explain effects of Knowledge, memory, expectations and context
parallel vs serial processing
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”, 6=“no”. Measure reaction time.
    • Vary the size of these memory sets
typical sternberg results
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?
a serial information processing model for sternberg task
A serial information processing model for Sternberg task

Make Decision

Is it a 7?

Perceive Stimulus

Is it a 3?

Is it a 9?



This serial information processing model predicts a linear increase

a parallel information processing model for sternberg task
A parallel information processing model for Sternberg task

Is it a 3?

Perceive Stimulus


Make Decision

Is it a 9?


Is it a 7?

This parallel information processing model also predicts a linear increase

  • Sometimes, behavioral results do not allow processes and representations to be uniquely identified (e.g. Sternberg task)
  • Identifiabilityrefers to the ability to specify the correct combination of representations and processes used to accomplish a task
how can we tell models theories apart
How can we tell models/theories apart?
  • Need converging evidence to tell theories apart
    • More behavioral data
    • Data from cognitive neuroscience
    • Data from neuropsychology
  • 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
    • cogneuro review slides