The document presents research on active learning strategies for robots that interact with human teachers. It found that classic active learning, which aims for query efficiency, can increase task difficulty and lead to slower, less accurate responses from teachers compared to more teacher-aware strategies. A hybrid strategy achieved intermediate results. The researchers conclude that considering the human perspective is important for active learning, as efficiency alone can undermine the interaction and learning.

1. Teacher-Aware
Active Robot Learning
Mattia Racca, Antti Oulasvirta and Ville Kyrki
ACM/IEEE International Conference on
Human-Robot Interaction (HRI), 2019
mattia.racca@aalto.fi

2. Why (active) learning robots?
2
Programming robots is hard, pre-programming them
for each task is harder impossible.

3. Why (active) learning robots?
3
Robot should learn by interacting with humans!
M. Racca and V. Kyrki, Active Robot Learning for Temporal Task models, HRI ‘18

4. The idea behind Active Learning
4

5. The idea behind Active Learning
5

6. The idea behind Active Learning
6
The agent can efficiently choose what to learn next.

7. The idea behind Active Learning
7
… and improve its model faster!

8. 8
Important aspects of Active Learning for HRI
1. Interactive Nature
Transparency
Design of
questions
Control over interaction
Timing of questions

9. 9
Important aspects of Active Learning for HRI
1. Interactive Nature
Transparency
Design of questions
Control over interaction
Timing of questions
2. Query Efficiency
Learning faster (with less data)

10. 10
Important aspects of Active Learning for HRI
1. Interactive Nature
Transparency
Design of questions
Control over interaction
Timing of questions
2. Query Efficiency
Learning faster (with less data)
But what about REAL users?

11. What if efficient query
selection is not best
for the interaction?
11

12. Can efficiency
indirectly
counter its
own benefits?
12
Query
Efficiency
Complex
questions
Questions
out of context
Harder for the teacher
● slower interaction
● more effort
● more errors!

13. Different types of Active Learning
13
1. CLASSIC
AL STRATEGY
(LEARNER C)
2. TEACHER-AWARE
AL STRATEGY
(LEARNER M)
3. HYBRID AL
STRATEGY
(LEARNER H)

14. An agent has to learn the value of a certain attribute a for a
set E of entities by making queries. We used the Animals with
Attributes 2* dataset with 50 animals (entities) and 85
semantic attributes.
Problem statement & Evaluation scenario
14
* Y. Xian, et al.. Zero-Shot Learning - A Comprehensive Evaluation of the Good, the Bad and the Ugly, T-PAMI

15. An agent has to learn the value of a certain attribute a for a
set E of entities by making queries. We used the Animals with
Attributes 2* dataset with 50 animals (entities) and 85
semantic attributes.
Problem statement & Evaluation scenario
15
* Y. Xian, et al.. Zero-Shot Learning - A Comprehensive Evaluation of the Good, the Bad and the Ugly, T-PAMI
YES
Do giraffes have
patches?

16. ● categories C over entities using WordNet
● Learner assumption: Entities in the same category are
more likely to share the same attribute value.
Problem statement & Evaluation scenario
16

17. ● categories C over entities using WordNet
● Learner assumption: Entities in the same category are
more likely to share the same attribute value.
Problem statement & Evaluation scenario
17

18. Classic AL: Uncertainty Sampling
18
● Learner C:
○ uses Uncertainty Sampling
○ selects the most uncertain query,
given the current model.
○ As expected efficient!

19. Classic AL: Uncertainty Sampling
19
● Learner C drawbacks
○ Some questions are difficult!
○ Topic or context switches!

20. ● Teacher-Aware strategy (Learner M)
○ Inspired by ACT-R declarative memory model,
saying “Information associated with recently
retrieved information is easier to retrieve”,
○ minimize the distance between consecutive
queries
In response to the drawbacks
20

21. ● Teacher-Aware strategy (Learner M)
○ Inspired by ACT-R declarative memory model,
saying “Information associated with recently
retrieved information is easier to retrieve”,
○ minimize the distance between consecutive
queries;
● Hybrid strategy (Learner H)
○ a tradeoff between Learner C and Learner M
In response to the drawbacks
21

22. Teacher-Aware AL: Memory Effort strategy
22

23. Simulation on the entire dataset:
● Perfect users (no errors, no distraction)
● Baseline: asks random questions and cannot leverage our
model to make predictions
Performance in Simulation
23

24. Performance in Simulation
24

25. User study: 26 participants,
the 3 strategies as conditions
(within-subject).
What about real users?
25

26. User study: 26 participants,
the 3 strategies as conditions
(within-subject).
Data logged:
● NASA TLX
● Q&A, response times,
prediction power
● Overall preferences
What about real users?
26

27. User study: 26 participants,
the 3 strategies as conditions
(within-subject).
Data logged:
● NASA TLX
● Q&A, response times,
prediction power
● Overall preferences
What about real users?
27
Our hypotheses:
Learner M makes the
participants reply (a)
faster and (b) with less
errors compared to
Learner C, with Learner
H achieving
intermediate results.

28. Results
28
*

29. (Unexpected) Results
29
*
*

30. (Unexpected) Results
30
*
*

31. (Unexpected) Results
31
* *

32. ● Higher response time and more errors for Learner C.
Discussion
32

33. ● Higher response time and more errors for Learner C.
○ stressful, unpredictable and requiring more
thinking
Discussion
33

34. ● Higher response time and more errors for Learner C.
○ stressful, unpredictable and requiring more
thinking
● Higher response time and more errors for Learner M.
Discussion
34

35. Discussion
35
● Higher response time and more errors for Learner C.
○ stressful, unpredictable and requiring more
thinking
● Higher response time and more errors for Learner M.
○ easy, natural and predictable

36. Discussion
36
● Higher response time and more errors for Learner C.
○ stressful, unpredictable and requiring more
thinking
● Higher response time and more errors for Learner M.
○ easy, natural and predictable
○ too easy? lowering attention or cause boredom

37. ● Higher response time and more errors for Learner C.
○ stressful, unpredictable and requiring more
thinking
● Higher response time and more errors for Learner M.
○ easy, natural and predictable
○ too easy? lowering attention or cause boredom
○ too predictable? using the same (maybe wrong)
answer
Discussion
37

38. Discussion
38
● Overall preferences:

39. ● Overall preferences:
● Learner C as efficient Mitigating difficulty!
Discussion
39

40. Discussion
40
● Overall preferences:
● Learner C as efficient Mitigating difficulty!
● Learner M as useless Frustration and boredom!

41. Discussion
41
● Overall preferences:
● Learner C as efficient Mitigating difficulty!
● Learner M as useless Frustration and boredom!
● AVOID USELESS QUESTIONS!

42. Conclusions
Can efficiency-driven Active Learning counter its
own benefits?
42

43. Can efficiency-driven Active Learning counter its
own benefits?
If we consider in the equation non-oracle users, yes!
But we just scratched the surface...
● We need a better understanding of interaction
aspects that can affect learning
● Strategies that can adapt to the specific user
Conclusions
43

44. Teacher-Aware Active Robot Learning
Mattia Racca, Antti Oulasvirta and Ville Kyrki
mattia.racca@aalto.fi
Thank you for the attention!
Code available at github.com/MattiaRacca
Can efficiency-driven Active Learning
counter its own benefits?
If we consider in the equation non-oracle
users and the interaction, yes!

45. 45
Tree building algorithm

46. 46
We model the probability of attribute a applying
to category c as
and then we maintain a prior over these
distribution. We can then compute the
probability of a applying to entity e as
and therefore predict attribute entities pairs, given our current model.
The update step of the model is the computation of the posterior distributions
given the user answer r as an observation.
Attribute-Category Model

47. 47
Learner C
Learner M
Learner H
Scores for each active learner

48. Assumption choice