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More on Recursion…. ….with Starlings. Nick Baumann Katherine Tech. Background. Recursion is uniquely human Humans have: Context-Free Grammar (CFG) Animals have: Finite-State Grammar (FSG). Ports have IR receiver and transmitter Holes allowed probing A hopper provided food - PowerPoint PPT Presentation
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More on Recursion…
Nick Baumann
Katherine Tech
….with Starlings
Background
Recursion is uniquely human
Humans have:• Context-Free Grammar (CFG)
Animals have:• Finite-State Grammar (FSG)
Experiment Apparatus
Ports have IR receiver and transmitter
Holes allowed probing
A hopper provided food
One station per animal for training
Shaping & Selection
Center hole flashing LED = food Initiation of Experiment Learning baseline FSG/CFG
• Only fast learners were used (green)• The others were dinner “The rate of
acquisition varied widely among the starlings that learned the task and was slow by comparison to other song-recognition tasks.”
Conditions
From a single adult male starling
A= Rattles B= Warbles
Context-Free GrammarA2B2
Finite-State Grammar (AB)2
Results
Nine of the eleven birds able to classify FSG and CFG sequences
Have the capacity to describe long strings – generative grammar Baseline of n=2Probed birds with n=3, n=4
Further tests done to ensure proper interpretation of data
Some Possibilities…
Classified patterns described by CFG/FSG grammars throughRote Memorization of training examplesLearn only FSG and CFG is the
complement setListening for
• A/B and B/A transitions• BB, AA, and AB motif pairs
Rote Memorization Testing
Transferred birds abruptly from the training stimuli to new sequences Baseline: n =2 Example: New CFG: AAAAAABBBBBB New FSG: ABABABABA
Starlings correctly classified the new CFG and FSG sequences Acquired general knowledge characteristic of the two grammars Birds did not memorize the training stimuli
CFG as a complement set
Made 16 new sequences based on 4 agrammatical patterns
Agrammatical Patterns: AAAA, ABBA, BBBB, and BAAB
Presented among grammatical sequences “The response patterns for the agrammatical probe
stimuli differed significantly from those for new (AB)2 stimuli for all four birds, and from those for new A2B2
stimuli for three of the four birds”
Listening for pairs and transitions
Classifying sequences by pairs at the start or end Ex. xxAB xxBB and AAxx ABxx
Counting A/B and B/A Transitions
Test possibility with agrammatical stimuli End: response times similar between AAAB and
BBBB and their counterpart (AB) 2 and A2B2
Transitions: discriminate between ABBA, BAAB, AAAA and BBBB and similar times with reference
Is Recursion Important?
More to speech than recursionPeople can still speak without itPremack 2004
• Voluntary control of sensory-motor systems
• Imitation/Teaching • Theory of the Mind• Vocabulary
Recursion in Humans
Marcus 2006Humans have better ability for
recursion
• No extensive training
• Generalize recursion to new words
Are Conclusions Valid?
Is it possible for finite-state grammar to mimic context-free grammar?Pattern recognition could lead to same
result Humans fail similar tests
The cats the dog the men walk chases run away.
Continued…
Perruchet and Rey 2004 “We report an experiment replicating the
results of F&H in humans, but also showing that participants learned the language without exploiting in any way the center-embedded structure. When the procedure was modified to make the processing of this structure mandatory, participants no longer showed evidence of learning.”
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