History and Some Cognitive Neuroscience History

8/24/11

History and some Cognitive Neuroscience

(Chapters 1 & 2)

8.24.2011

History

Timeline showing early experiments studying the mind in the 1800s and events associated with the rise of behaviorism in the 1900s

Psychophysics! Fechner color effect:! http://www.itp.uni-hannover.de/~zawischa/ITP/benhamtop.html! Fechner"s Law – a subjective sensation is proportional to the logarithm of the stimulus intensity!

S = K Log I! Gustav Fechner! S = Psychological sensation! 1801-1887 I = Physical intensity of the stimulus!

I * 3 = S + S! I * 3 * 3 = S + S + S!

Geometric increase in stimulus intensity leads to an additive increase in sensation.!

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Unconscious inference •# Some of our perceptions are the result of unconscious assumptions we make about the environment Hermann Von Helmholtz! •# We infer much of what we know 1821-1894 about the world

Inﬂuenced Ebbinghaus, Wundt, Helmholtz! Math Modeling! The mind and body are different sides of one reality.!

Gustav Fechner! 1801-1887 "Every sensation, presents itself as an indivisible unit; and it is quite impossible to read any clear meaning into the notion that they are masses of units combined."!

William James! 1842-1910

History

Timeline showing early experiments studying the mind in the 1800s and events associated with the rise of behaviorism in the 1900s

Pavlov (1849-1936) Thorndike (1874-1959)

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Classical (Pavlovian) Conditioning! (Dogs)! CS – ! UCS –! UCR – ! CR –!

Pavlov (1849-1936) Law of Effect! (Cats)! Puzzle Box! Precursor of $Operant" or $Instrumental" Conditioning! Alpha, Beta Tests (ASVAB)! $Active Learning"!

Thorndike (1874-1959)

Pavlov’s Discovery: Classical Conditioning

History

Timeline showing early experiments studying the mind in the 1800s and events associated with the rise of behaviorism in the 1900s

Pavlov (1849-1936) Thorndike (1874-1959)

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History

Timeline showing early experiments studying the mind in the 1800s and events associated with the rise of behaviorism in the 1900s

Pavlov (1849-1936) Thorndike (1874-1959)

Early experimental psychology: Behaviorism Inﬂuential ﬁgures: ! John B. Watson, ! B. F. Skinner!

Burrhus Skinner! •#Guiding Principles:! 1904-1990 –# Only focus on that which is observable.! –# Explain behavior; not thought, the mind, consciousness, etc.! •#Contribution to Cognitive Psychology! –# Emphasis on rigorous experimentation.! –# Powerful theories of learning! •# Classical Conditioning (Ivan Pavlov)! –# e.g., Pavlov!s dog learned relationship between bell and food.! •# Operant Conditioning (Edward Thorndike)! –# e.g., A dog learns to sit for a treat.!

John Broadus Watson 1878-1958

“Give me a dozen healthy infants, well- formed, and my own speciﬁed world to bring them up in and I'll guarantee to take any one at random and train him to become any type of specialist I might select – doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors. I am going beyond my facts and I admit it, but so have the advocates of the contrary and they have been doing it for many thousands of years. [Behaviorism (1930), p. 82]!

John Broadus Watson 1878-1958

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The Decline of Behaviorism

•# A controversy over language acquisition! •# Skinner (1957)! –# Argued children learn language through operant conditioning! •# Children imitate speech they hear! •# Correct speech is rewarded

The Decline of Behaviorism

•# Noam Chomsky (1959)! –# Argued children do not only learn language through imitation and reinforcement! •# Children say things they have never heard and can not be imitating ! •# Children say things that are incorrect and have not been rewarded for! –# Language must be determined by inborn biological program (LAD)! –# “Colorless green ideas sleep furiously”

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•# What happens when the rats are placed in a different arm of the maze?! •# The rats navigated to the speciﬁc arm where they previously found food! Edward Chace Tolman –# Supported Latent Learning, not 1886-1959 stimulus-response learning!

•#Tolman (1938)!

(a)#Rat initially explores the maze; ! (b)#then learns to turn right to obtain food at B when it starts at A; ! (c)#when placed at C, the rat turns left to reach the food at B.

Limitations of Behaviorism

•# Failures to account for aspects of human behavior! •# Over-emphasis on animal experimentation! •# Language! •# Skinner suggested language was learned through basic principles of operant conditioning.! •# i.e., we learn to say what is rewarded! •# Fails to account for Generativity of language.! •# The creation of novel utterances % that have never been rewarded in the past.! •# e.g., Chomsky (linguist)

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!#Failure to consider intervening mental processes!

"#Behaviorism:!

Stimu Response li s "#Cognitive Psychology:!

Stimu Mental Response li Processes s

"#Stimulus (memorize this list)! !# lion, onion, Bill, firefighter, carrot, % zebra, John, clerk, Tom, nurse, cow! "#Response (recall)! !# lion, zebra, cow, onion, carrot, % firefighter, clerk , nurse, John, Bill, Tom! "#Mental Processes! !# Strategies, grouping, reorganization, etc

The Cognitive Revolution

•# Shift from behaviorist"s stimulus-response relationships to an approach that attempts to explain behavior in terms of the mind

FIG 1.12

Timeline showing events associated with the decline of the influence of behaviorism (above the line) and events that led to the development of the information-processing approach to cognitive psychology (below the line).

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Overview of Different Approaches

Stimu Mental Response li Processes s

!#Philosophy! !#Think about mental processes! !#Structuralism (Introspection)! !#Try to directly tap into mental processes! !#The What of experience! !#Behaviorism! !#Study stimulus-response relationships! !#Ignore mental processes! !#Cognitive Psychology! !#Study stimulus-response relationships! !#Make inferences about mental processes! !#The How of experience! !#Mathematical Modeling!

The rebirth of the study of the mind

•# The digital revolution! –# Information Processing: inputs are transformed, in stages, to generate outputs.! –# Flow diagrams for digital computers.! •# Flow diagrams for the mind.! –# Colin Cherry (1953): selective attention.! –# Broadbent"s information processing model of attention.

A model for selective attention! How can you stay focused on your conversation?!

You must ﬁlter out extraneous information.

“I hate that Shaw guy.”!

Attention can still be broken into.! (we will explore these ideas more in chapter 4).

Inputs Filter Detector To memory

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Studying the Mind

•# To understand complex cognitive behaviors: •# Measure observable behavior •# Make inferences about underlying cognitive activity •# Consider what this behavior says about how the mind works

Researching the Mind

•# Behavior approach measures relationship between stimuli and behavior •# Physiological approach measures relationship between physiology and behavior •# Both contribute to our understanding of cognition

Researching the Mind – Memory Consolidation

•# Memory for recent events is fragile

•# If processing is disrupted, recent memories can fail to be consolidated

•# New information can interfere with memory consolidation

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•# BehaviorResearching approach the Mind – Memory Consolidation •# Muller and Pilzecker (1900) had participants learn two lists of words

•# Independent variable:

•# One group learned the second list immediately after the first list

•# The other group experienced a six-minute delay between learning the lists

•# Dependent variable:

•# Memory (recall) for the first list of words

Results of the Gais et al. (2007) experiment in which memory for word pairs was tested for two groups. The sleep group went to sleep shortly after learning a list of word pairs. The awake group stayed awake for quite a while after learning the word pairs. Both groups did get to sleep before testing, so they were equally rested before being tested, but the performance of the sleep group was better.

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Cognitive Science •# Interdisciplinary study of the mind •# Psychology •# Computer science •# Cognitive anthropology •# Linguistics •# Neuroscience •# Philosophy •# Physiology •# Molecular Biology •# Physics •# Education

Descartes 1596-1640 Broca 1824-1880 Wernicke 1848–1905 Luria (1902-1977)

Timeline showing early experiments studying the mind in the 1800s and events associated with the rise of behaviorism in the 1900s

Pavlov (1849-1936) Thorndike (1874-1959)

Cognitive Neuroscience!

•# The microstructure of the brain

•# Neurons

•# Glia

•# Hold neurons in place,

•# Supply nutrients and oxygen to neurons

•# Insulate neurons from one another

•# Destroy pathogens and remove dead neurons.

•# Also involved in communication

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History of Neuroanatomy

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Microstructure: The Neuron

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a) Action potentials are recorded from neurons with tiny microelectrodes that are positioned inside or right next to the neuron’s axon. These potentials are displayed on the screen of an oscilloscope and are also sent to a computer for analysis. (b) An action potential recorded by a microelectrode looks like this. The inside of the axon becomes more positive, then goes back to the original level, all within 1 millisecond (1/1,000 second). (c) A number of action potentials displayed on an expanded time scale, so a single action potential appears as a “spike”.

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Microstructure: The Neuron

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Microstructure: The Action Potential

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The Action Potential

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Microstructure: The Synapse

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