1. More on Recursion… Nick Baumann Katherine Tech ….with Starlings

2. Background Recursion is uniquely human Humans have: Context-Free Grammar (CFG) Animals have: Finite-State Grammar (FSG)

3. Experiment Apparatus Ports have IR receiver and transmitter Holes allowed probing A hopper provided food One station per animal for training

4. 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.”

5. Conditions From a single adult male starling A= Rattles B= Warbles Context-Free Grammar A 2 B 2 Finite-State Grammar (AB) 2

6. 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=2 Probed birds with n=3, n=4 Further tests done to ensure proper interpretation of data

7. Some Possibilities… Classified patterns described by CFG/FSG grammars through Rote Memorization of training examples Learn only FSG and CFG is the complement set Listening for A/B and B/A transitions BB, AA, and AB motif pairs

8. 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

9. 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 A 2 B 2 stimuli for three of the four birds”

10. 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 A 2 B 2 Transitions: discriminate between ABBA, BAAB, AAAA and BBBB and similar times with reference

11. Is Recursion Important? More to speech than recursion People can still speak without it Premack 2004 Voluntary control of sensory-motor systems Imitation/Teaching Theory of the Mind Vocabulary

12. Recursion in Humans Marcus 2006 Humans have better ability for recursion No extensive training Generalize recursion to new words

13. 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.

14. 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.”