Transcript The use of Models - NAU jan.ucc.nau.edu web server

Information Processing Model of
Cognition
• First Meta-theory in cognitive science – a
all encompassing theory designed to
explain cognition
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The Use of Models
• Hydraulic models of human behavior- Romans
believed the heart pumped fluids that caused
movement
• Descartes – mechanical model, the body
functions like a machine
• British empiricists- model base upon physics
• Associationists – model based upon chemistry
• 1950’s computer model – information processing
model
• 1980 brain model - connectionism
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7 Themes of Cognition
• Attention – different types are important
• Automatic and conscious processing
• Data driven versus conceptually driven
processing
• Representations – how memories are stored
• Implicit versus explicit memory
• Metacognition
• The Brain
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Research Methods Used
• Correlational studies – are two or more
factors or variables related
• Experimental studies – manipulate one or
more variables and control others
• Quazi-experimental – the variable of
interest cannot be manipulated, usually
involves subject variables
• Single case – use of one subject – most
frequently used in neurocognition
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Methods for Measuring Cognition
• 1. Reaction time – measure time between
stimulus and response
• 2. Accuracy measurements
– Simple – how many mistakes were made
– Complex – look for a pattern of errors
• 3. Trials to criterion
• 4. Relearning – learn a task. After a delay
how long did it take to relearn the task
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Guiding Analogies
Channel Capacity:
An early analogy for the limited capacity of the
human information-processing system.
The Computer Analogy:
Human information processing may be similar to
the sequence of steps and operations in a
computer program, similar to the flow of
information from input to output when a
computer processes information.
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The Atkinson and Shiffrin Model
The Atkinson and Shiffrin Model of Human Memory
Encoding: The act of taking environmental stimulation and
converting it to a usable mental form (electrical signals).
• Three memory components: sensory memory, shortterm memory, and long-term memory.
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Examples
• Multiplying 2 X 3 =
• Lexical Decision Task: A timed task in which
people decide whether letter strings are or are
not English words.
– Takes longer to decide if a non-word is real than a
real world
– Word Frequency Effect: The effect which states that it
takes significantly longer to judge words of lower
frequency than it does to judge high-frequency words.
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The Strict Information Processing
Approach
• Sequential Stages of Processing: An
assumption in most process models that the
separate stages of processing occur in a fixed
sequence, with no overlap of the stages.
• Independent and Nonoverlapping Stages: The
assumption in the strict information processing
approach that the stages of processing are
independent of one another in their functioning,
and that they do not overlap in time.
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Some Problems
• Parallel Processing: Any mental
processing in which two or more
processes or operations occur
simultaneously.
• Model could not explain how context could
speed up processing such as during
priming tasks
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The Modern Cognitive Approach:
Cognitive Science
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Cognitive Science
• The study of human thought, using all
available scientific techniques and
including all relevant scientific disciplines
for exploring and investigating cognition.
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Updating the Standard Theory
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Two Types of Processing
• Bottom-up or data driven
• Top-down or conceptually driven
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Summary
The strict-information processing approach to
cognition was replaced with a broader, more
inclusive approach now known as cognitive
science. This approach described cognition as
the coordinated, often parallel operation of
mental processes within a multicomponent
memory system. The approach is deliberately
multidisciplinary, accepting evidence from all the
sciences interested in cognition.
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Brain Anatomy
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Brain Anatomy (con’t.)
• Neocortex or cerebral cortex: The top
layer of the brain responsible for higherlevel mental processes.
– The lobes of the neocortex: the frontal lobe,
parietal lobe, occipital lobe, and temporal lobe
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Four Lobes of the Neocortex
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Lower Brain Structures
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Brain Anatomy (con’t.)
Three other subcortical (below the neocortext) structures
are especially important to neurocognition:
thalamus: the gateway to the cortex; almost all messages
entering the cortex come through the thalamus
corpus callosum: the primary bridge across which messages
pass between the left and right halves or hemispheres of the
neocortex
hippocampus: an internal brain structure strongly implicated
in the storing of new information into long-term memory
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Principles of Functioning
• Contralaterality: The principle that control
of one side of the body is localized in the
opposite-side cerebral hemisphere.
• Hemispheric Specialization: The principle
that each cerebral hemisphere has
specialized functions and abilities.
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Split-Brain Research and
Lateralization
• Research on split-brain patients
• Principle of lateralization
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Basic Neurology
• Neurons: The basic building block of the
brain and the entire nervous system, a
neuron is a cell that is specialized for
receiving and transmitting a neural
impulse.
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The various structures of the
neuron
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Basic Neurology (con’t.)
• Synapses: The region where the axon
terminals of one neuron and the dendrites
of another come together is the synapse.
• Neurotransmitter: The chemical
substance released into the synapse
between two neurons, responsible for
activating or inhibiting the next neuron in
sequence.
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Methods of Investigation
• Lesions: Used by Sperry; the site and extent of
the brain lesion are important guides to the kind
of disruption in behavior that is observed and
vice versa.
• Direct Stimulation: Pioneered by Penfield; the
patient in brain surgery remained conscious
during surgery and was administered minute
electrical charges to the exposed brain, thus
triggering very small regions.
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Exposed cortex of one of Penfield’s
patients
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Methods of Investigation (con’t.)
• Imaging Technology
• Magnetic Resonance Imaging (MRI): Gives clear
pictures of the structure of the brain.
• Functional MRI: Image shows regions of the brain
with heightened neural activity, with different colors
reflecting high or low levels of blood flow, oxygen
uptake, and the like.
• PET scans- use or radioactive labels attached to
glucose
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Methods of Investigation (con’t.)
• Electrocephalograms (EEG): Electrodes
are attached to the subject’s scalp, and
the device records the patterns of brain
waves.
• Event-Related Potentials: The
momentary changes in electrical activity of
the brain when a particular stimulus is
presented to the subject.
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Neural Net Models: Connectionism
• Connectionist models are often called
neural net models or parallel distributed
processing (PDP) models; the three terms
are synonymous. All refer to a computerbased technique for modeling complex
neural based systems.
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An early connectionist model by
McClelland and Rumelhart
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