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- Michael Lamport Commons
- Patrice Marie Miller
- Harvard Medical School
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- Several reasons for doing this are
- Understand the most basic task actions and how they are controlled<=
/li>
- Be more exact about how these basic units get combined to form more
complex tasks
- Better understand evolution
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- This model can be used to determine behavioral stage
- MHC orders tasks in t=
erms
of Hierarchical complexity
- A task action is defined as more hierarchically complex when the hi=
gher
order action
- is defined in terms of the actions at the next lower order
- organizes these lower-order actions
- in a non-arbitrary way
- Explains stages of development
- A Stage name and number corresponds to the order of hierarchical
complexity of a task it correctly completes
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- Stage 1 describes that organisms complete tasks in which they are
required to either act or sense, but they do not complete tasks that
coordinate the two
- First, we examine some Stage 1 tasks that animals might complete
- Second, we examine evidence for animals that never progress further
than Stage 1 in any area
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- Before Stage 1, however, we describe stage 0
- At stage 0, both the detection of stimuli and the production of
responses are exact
- There is no generalization
- All examples have to have been programmed
- Robots and computers respond this way
- For computers, only written programmed learning is possible
- The exception are neural networks, especially stacked neural netwo=
rks
- We would assert that there are no animals that function at this stag=
e
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- The criterion for classifying action as Stage 1 is
- The organism engages =
in a
single action at a time
- These actions are not
coordinated with other actions
- There are coordinatio=
ns of
stimuli
- Both the detection of stimuli or the production of responses are
somewhat flexible
- But the relationship between them is not
- For example, when water moves, mollusks open their shells reflexive=
ly
- If something touches their membrane, the shells close There is very little varia=
bility
in these responses
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- Zooplankton are floating or weakly swimming
- They rely on water currents to move great distances
- Microzooplankton are usually less than 200 mm
- Protozoa are a eukaryote subclass plankton
- They are mobile and heterotrophic
- They use organic substrates to get carbon for growth and developme=
nt
- Most protozoans are around 001–005 mm but up to 05
- They are predators upon unicellular or filamentous algae, bacteria,=
and
microfungi
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- A Taxis is an organism’s directed physical action in response =
to a
specific stimulus
- A taxis can be a directional response or a non-directional response
(kinesis)
- Phototaxis: flagellate
protozoans of the genus Euglena move towards a light source
- Chemotaxis: Cells suc=
h as
the free-living amebas or the wandering cells of the Metazoa may de=
tect
the direction of a potential food source through the chemicals that=
the
food sheds
- Other kind of Taxis behaviors include: anemotaxis (stimulation by
wind), barotaxis (pressure), galvanotaxis (electrical current), geo=
taxis
(gravity), hydrotaxis (moisture), phototaxis (light), rheotaxis (fl=
uid
flow), thermotaxis (temperature changes) and thigmotaxis (physical
contact)
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- Phagocytosis: a way of obtaining nutrients that involves an organism
completely surrounding a food particle
- Amoebae: food object surrounded by their pseudopods
- In another protozoan, called a ciliate, there is a specialized groo=
ve
in the cell where phagocytosis takes place
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- The most complex stage 1 system are reflexes
- A reflex is a biologically-based system linking stimulus to response=
- This may be mediated by a reflex arc only a few neurons long
- Here, the stimulus and the response are coordinated
- But the coordination is automatic
- It is simply due to the neural connection
- For animals without neurons, we do not believe there can be true
reflexes
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- For example, habituation of a reflex can occur
- Habituation may be due simple process as neural fatigue
- Likewise with sensitization
- What about stimulus generalization?
- Stimulus generalization results from similarity of the original
eliciting stimulus to other stimuli
- As a stimulus becomes less and less similar, it is less likely to
elicit the same response
- For simple, physical stimuli the degree of similarity can be measur=
ed
quantitatively rather than in hierarchical terms
- So, behavior remains at stage 1
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- One stimulus precedes closely before another stimulus
- It can come to elicit=
the
same or similar response
- Pairing of the unconditioned and stimulus to be conditioned is not a
task that the animal must actively solve
- This is so even though the stimuli must be salient
- The two stimuli are arbitrarily paired, either by an accident of nat=
ure
or by an experimenter
- This does not constitute an increase in the hierarchical complexity =
of
the task that must be solved
- The organism does not temporally or in some other way organize actio=
ns
in order to more adequately accomplish this
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- Even very primitive animals differentially respond to stimuli, for
example, rejecting non-food items
- They do not change their behavior based
- on this environmental consequences
- feedback following those responses
- Every encounter with a food or a non-food object is like a new encou=
nter
- Such animals may not operantly hunt for prey or forage
- Some animals change their behavior in response to consequences
- The consequences lead to them to Stage 2 behavior in which they
coordinate action with sensory input
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- At Stage 2, animals coordinate operant action with perception or they
coordinate two or more actions
- Hunting behavior is controlled by consequences
- (eg most predatory fish, insects) are performing at this stage
- Corrette (1990) observed prey capture in the praying mantis
- They coordinated capture and strike movements
- Coordinating of multiple behaviors such as looking, reaching and
grasping require Stage 2 circular sensory and motor action
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- We have described stage of actions by various simple organisms
- The first two orders of hierarchical complexity adequately described=
the
tasks they accomplish
- Simple one-celled organisms that were not part of groups of cells,
functioned at stage 1
- Some multiple cell organisms that operantly conditioned functioned at
stage 2
- Some animals such as mammals probably never function only at stage 1=
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