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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.

Organizational notes

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

(from: Schunn et al. 2005)

Organizational notes

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)

Levels of analysis example

Levels of Analysis Example

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

An early version of the information processing approach purely bottom up or stimulus driven

An early version of the information-processing approach purely bottom up or stimulus-driven

A demonstration of top down processing

A Demonstration of Top-Down Processing

Organizational notes

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

Organizational notes

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

Organizational notes


  • 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

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