Organizational Notes no study guide no review session not sufficient to just read book and glance at...
-
date post
19-Dec-2015 -
Category
Documents
-
view
219 -
download
0
Transcript of Organizational Notes no study guide no review session not sufficient to just read book and glance at...
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?
… 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/
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)
Cognitive Science
Computer Science/ Artificial Intelligence
Neuroscience
Philosophy
Cognitive Psychology Linguistics
Understanding ComputationBuilding computer models that learn from the environment
To understand limits of theories
To understand structure of language
To understand howthe brain works
For behavioral data in various tasks; mental representations and processes
We will focus mostly on insights from Cognitive Psychology
Interdisciplinarystudy of intelligentbehavior
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
• 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
• 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 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
• Bottom-up processing• Top-down processing• Parallel processing• Serial processing
(Kleffner & Ramachandran, ’92)
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
Top-down processing: perception affected by knowledge of world
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
"The steady drip is worse than a drenching rain."
(for more info: http://www.haskins.yale.edu/haskins/MISC/SWS/SWS.html)
http://psiexp.ss.uci.edu/research/teachingP140C/demos/sinewavespeech.aif
http://psiexp.ss.uci.edu/research/teachingP140C/demos/naturalutterance.aif
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:– http://shamslab.psych.ucla.edu/demos/– http://www.cns.atr.jp/~kmtn/soundInducedIllusoryFlash/index.html– http://www.cns.atr.jp/~kmtn/soundInducedIllusoryFlash2/– For more information on this effect see:
http://shamslab.psych.ucla.edu/publications/SCR-reprint.pdf– note: demo might not work on your particular computer
• Demo shows that visual perception affected by auditory perception
Top-down processing
Later stages of processing affect
earlier stages
can explain effects of Knowledge, memory,
expectations and context
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
• 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
Perceive Stimulus
Is it a 3?
Is it a 9?9
Is it a 7?
Make Decision yes
This serial information processing model predicts a linear increase
A parallel information processing model for Sternberg task
Perceive Stimulus
Is it a 3?
Is it a 9?
9
Is it a 7?
Make Decision yes
This parallel information processing model also predicts a linear increase
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
How can we tell models/theories apart?
• Need converging evidence to tell theories apart– More behavioral data– Data from cognitive neuroscience– Data from neuropsychology