ACT-R 6 Official Release

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ACT-R 6Official Release

• Dan Bothell
• Carnegie Mellon University

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(No Transcript)
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Brief History

• Proposed at the 2002 Workshop
• Concurrently with ACT-R 5s release
• Initial description at the 2003 Workshop
• Early prototype
• Claimed a 2005 Workshop release
• Discussion session after ICCM 2004
• Fleshed out some issues with syntax
• Here it is!
• Fully functional
• Used it for the 2005 Summer School

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What is ACT-R 6?

• The same theory as ACT-R 5
• Rewritten implementation
• Eliminate unnecessary legacy code
• Unify/standardize the buffer mechanism
• Better integration of the Cognitive and
  Perceptual/Motor components
• No longer an ACT-R/PM
• Make the whole system modular
• Easy to add new components
• Easy to remove/replace existing ones

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How similar is it to ACT-R 5?

• Very similar
• Most of the commands are still there
• reset, clear-all, sgp, p, add-dm, run,
• Models look basically the same
• Same equations
• Procedural
• Declarative memory
• With basically the same parameters
• Same defaults and usage
• Same Perceptual and Motor modules

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Why should I use it?

• It cleans up some issues that can make ACT-R 5
  tricky to work with
• It has new features
• To make things easier for modeling
• To add some requested capabilities
• It is easier to extend and modify
• Easier to distribute and combine extensions
• In many cases it is faster than ACT-R 5

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Things that were cleaned up

• Overall structure
• Buffers and Chunks
• Declarative memory
• Productions
• Module states
• Vision module
• Production compilation
• Available commands

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Things that were cleaned up

• Overall structure
• Buffers and Chunks
• Declarative memory
• Productions
• Module states
• Vision module
• Production compilation
• Available commands

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Basic structure

• A central event scheduling system
• Independent of the theory itself
• A set of modules
• All treated equally
• Should each be independent
• May have one or more buffers as an interface
• Responsible for scheduling its own events

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Things that were cleaned up

• Overall structure
• Buffers and Chunks
• Declarative memory
• Productions
• Module states
• Vision module
• Production compilation
• Available commands

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Buffers

• They all work the same
• Can hold one chunk
• Relay queries and requests to/from a module
• The chunk is a copy
• Doesnt exist outside of the buffer until it is
  cleared
• Changes are not reflected back to the original
  chunk
• Essentially chunk creation scratch pads

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Chunks

• Not just for Declarative memory
• Any module can create/use chunks
• The set of all chunks does NOT equal DM!

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Things that were cleaned up

• Overall structure
• Buffers and Chunks
• Declarative memory
• Productions
• Vision module
• Module states
• Production compilation
• Available commands

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Declarative Memory

• Chunks that are added explicitly
• Add-dm
• Chunks merge into DM from buffers
• All buffers chunks go to DM when cleared
• Mergings are the references for BLL
• Not the LHS usage as in ACT-R 5
• Because buffers hold copies, DM chunks cant be
  changed from within a production
• Previously it was a recommendation

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Things that were cleaned up

• Overall structure
• Buffers and Chunks
• Declarative memory
• Productions
• Module states
• Vision module
• Production compilation
• Available commands

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General Production Changes

• No LHS Retrievals
• Cant use !eval! in the slot value position
• More rigorous syntax checking
• Doesnt assume what you want when theres an
  inconsistency
• LHS ordering not important
• (p test
• goalgt
• isa goal
• - value value
• retrievalgt
• isa fact
• slot value
• gt )

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Productions LHS

• Only four possible conditions available
• buffergt
• Test the chunk in the buffer just like in 5
• !eval! or !safe-eval!
• !bind! or !safe-bind!
• Same as in ACT-R 5
• Safe- versions accepted by production compilation
• ?buffergt
• Query the buffer or its module
• Come back to queries later

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Production RHS

• Essentially the same operators as in 5
• Removed the obsolete ones
• !pop!, !push!, !retrieve!, etc.
• Standardized the mechanism for all buffers
• All buffers treated equally
• Obviously different buffers do different things,
  but a buffers module is where that
  differentiation occurs

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Possible RHS actions

• buffergt
• -buffergt
• buffergt
• !eval! and !safe-eval!
• !bind! and !safe-bind!
• !output!
• !stop!

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RHS actions

• buffergt
• !eval! and !safe-eval!
• !bind! and !safe-bind!
• !output!
• All the same as in ACT-R 5
• The safe- versions do not inhibit the production
  compilation mechanism
• !stop!
• Not actually new, but does work now
• Generates a break event in the scheduler
• Terminates the current run command

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RHS buffergt

• -buffergt
• Clears the chunk from the buffer
• Thats it!
• Does not result in any action by the module
• Unlike ACT-R 5 where that could also cause the
  corresponding module to reset/clear

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RHS buffergt

• buffergt isa chunk-type
• modifier slot request parameter value
• or
• buffergt chunk-reference
• Sends a request to the module
• Always clears the buffer implicitly
• Essentially the same as ACT-R 5

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Things that were cleaned up

• Overall structure
• Buffers and Chunks
• Declarative memory
• Productions
• Module states
• Vision module
• Production compilation
• Available commands

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Buffer queries

• Replaces the -state buffers
• Syntax
• ?buffergt
• - query value
• Either true or false
• No bindings
• Must all be true for production to match
• Examples
• ?retrievalgt ?visualgt
• state busy - state error
• buffer empty buffer check

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Queries continued

• Every buffer/module must respond to
• State
• Values busy, free, or error
• Buffer
• Values full, empty, requested or unrequested
• Others can be added by a module writer
• Modality for the current PM modules for example

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Things that were cleaned up

• Overall structure
• Buffers and Chunks
• Declarative memory
• Productions
• Module states
• Vision module
• Production compilation
• Available commands

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Vision Module

• Removed the attended slot from visual-location
  chunks
• Replaced with
• a RHS request parameter
• visual-locationgt
• isa visual-location
• attended nil
• A LHS query
• ?visual-locationgt
• attended nil
• Good because now visual-locations can merge
  properly without the changing attended slot
• The query can match nil to new but a LHS slot
  test couldnt

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Vision Module cont.

• Attention Shifts changed from
• visualgt
• isa visual-object
• To
• visualgt
• isa move-attention
• No longer need the scale slot in visual-objects
• Easier to read in productions
• The analogy to declarative didnt seem all that
  helpful

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Things that were cleaned up

• Overall structure
• Buffers and Chunks
• Declarative memory
• Productions
• Module states
• Vision module
• Production compilation
• Available commands

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Production Compilation

• The same general theory as 5
• Combine consecutive productions into one
• Incorporate requested chunks and remove the
  request
• Only do safe compilations
• Mechanism is now split into two distinct steps
  and applied on a buffer-by-buffer basis
• Check for possibility of composition
• Perform the composition
• More robust than the mechanism in 5
• Slightly more restricted than the 5 mechanism

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Production Compilation cont.

• Applies to all buffers (even user created)
• Basic mechanism is that there are 4 styles of
  buffers
• Goal, retrieval, perceptual, and motor
• Any buffer can be set to any style
• New styles can be added
• Existing styles can be modified for both steps

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Things that were cleaned up

• Overall structure
• Buffers and Chunks
• Declarative memory
• Productions
• Vision module
• Module states
• Production compilation
• Available commands

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Commands

• Removed some duplicate commands
• set-general-base-levels, set-all-base-levels,
  set-base-levels, setgeneralbaselevels,
  setallbaselevels, setbaselevels ?
  set-base-levels
• The PM commands have had the pm- removed
• For example pm-proc-display is now proc-display
• Commands referencing obsolete items removed
• In particular anything that included wme
• Sgp sets parameters for all modules

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New Features

• Request parameters
• Declarative finsts
• Sources of activation
• Multiple models
• Strict Harvesting
• P command

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New Features

• Request parameters
• Declarative finsts
• Sources of activation
• Multiple models
• Strict Harvesting
• P command

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Request parameters

• Buffer specific parameters
• Valid no matter what the chunk-type
• Always a keyword (which distinguishes it from an
  actual slot)
• Examples
• visual-locationgt
  retrievalgt
• isa visual-location isa
  any-chunk-type
• attended nil
  recently-retrieved nil

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New Features

• Request parameters
• Declarative finsts
• Sources of activation
• Multiple models
• Strict Harvesting
• P command

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Declarative Finsts

• Cannot modify chunks in DM in a production
• Major reason for changing chunks in DM was to
  mark them to prevent retrieval
• Now there are automatic markers just like vision
• They are limited in time and number
• settable with parameters
• Indicated with the request parameter
  recently-retrieved
• retrievalgt
• isa fact
• recently-retrieved nil

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New Features

• Request parameters
• Declarative finsts
• Sources of activation
• Multiple models
• Strict Harvesting
• P command

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Sources of activation

• All buffers are potential sources now
• Each buffer has a separate parameter like ga for
  the goal buffer
• ga defaults to 1
• All others default to 0
• mas now also used to enable/disable spreading
  activation since setting ga to 0 is not
  sufficient

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New Features

• Request parameters
• Declarative finsts
• Sources of activation
• Multiple models
• Strict Harvesting
• P command

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Multiple Models

• Out of the box ACT-R 6 supports multiple models
• Any number of models can be loaded
• Each has its own set of modules, chunks, and
  parameters
• Can be run synchronously or asynchronously
• Determined when loaded
• Not adjustable afterwards

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New Features

• Request parameters
• Declarative finsts
• Sources of activation
• Multiple models
• Strict Harvesting
• P command

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Strict harvesting

• New mechanism of productions
• When a buffer is matched on the LHS of a
  production it is automatically cleared on the RHS
  unless there is an buffer action to keep it
  around
• Parameterized so that one can specify which
  buffers get strict harvested
• Out of the box all but the goal buffer do
• Cleans up issues with
• References for BLL
• Production compilation
• Micro-managing perceptual buffers

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New Features

• Request parameters
• Declarative finsts
• Sources of activation
• Multiple models
• Strict Harvesting
• P command

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Experimental addition P

• Exactly like p except slot-names can be
  variablized
• On both the LHS and the RHS
• Only slot-names not the chunk-type
• Limited variability (for now at least)
• Will not do any binding the variable must be
  bound elsewhere
• Only one level deep per buffer test

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Example P uses

• (p search
• goalgt
• isa search
• retrievalgt
• isa strategy
• constraint c
• value v
• gt
• visual-locationgt
• isa visual-location
• c v
• )

• (p check
• goalgt
• isa check
• which-slot s
• which-value v
• retrievalgt
• isa memory
• s v
• gt
• )

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More on P

• Does work with production compilation!

(p production-89 search strat
goalgt isa search gt
visual-locationgt isa visual-location
kind text )
(p search goalgt isa search
retrievalgt isa strategy constraint c
value v gt visual-locationgt isa
visual-location c v )
Strat isa strategy constraint kind value
text
...
?

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Other issues

• Extending the system
• Current performance

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Extending via new Modules

• All modules are built the same way
• Including the defaults
• Can remove or replace any module
• Placing a file in the modules or tools directory
  with a .lisp name will cause it to be loaded
• Eventually would like to have a database of
  available modules and tools that people can use
• No how to docs right now, but the current
  modules serve as examples and there is an API doc
  that describes the available functions

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Modifying the base modules

• Declarative and Procedural modules are now more
  user configurable
• All the equations have override hooks like
  similarity did previously
• BL-HOOK
• SPREADING-HOOK
• PARTIAL-MATCHING-HOOK
• NOISE-HOOK
• SIM-HOOK
• SJI-HOOK
• UTILITY-HOOK
• UTILITY-C-HOOK
• UTILITY-P-HOOK
• Should relieve people of needing to hack the main
  code

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Performance Evaluation

• Has not been highly optimized yet
• Used the tutorial models as a benchmark because
  they touch all the main components
• Used ACL 6.2 on Windows XP and MCL 5.0 on Mac OS
  X 10.4
• Need to increase the MCL heap under OS X
• (cclset-preferred-size-resource
  heap-size-in-bytes)
• Basic speed and size comparison
• Using the time function

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Comparison
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More Information

• Tutorials show the new system in use
• Test models in the distribution are the commented
  conversion of the ACT-R 5 tutorial models
• User manual
• not yet sorry
• Can always look at the source code
• A little more structured/spread out
• Slightly more commented

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Where can I get it?

• The ACT-R website
• http//act-r.psy.cmu.edu
• Updated when there are significant changes
• Via Subversion
• Always the most up to date code
• Version control software available from
• http//subversion.tigris.org
• All files are under version control
• Including the tutorial, docs, and the environment
• Available from our server at
• svn//alba.psy.cmu.edu/usr/local/svnroot/actr6

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Questions?