1. Effect of Prior Knowledge and Wisdom of Crowds
Serial Order Memory
Effect of Prior Knowledge and Wisdom of Crowds

2. Demonstrations Experiment 1 (Prior knowledge)
Experiment 2a (Serial Recall)
study sequence of still images
Experiment 2b (Serial Recall)
study video

3. Research Goals Wisdom of crowds Analyze effect of prior knowledge
Can we recover original sequence of events based on recollected order from a group of individuals?
Models:
Thurstonian model
Perturbation model
Analyze effect of prior knowledge
How well can we order events a priori (i.e, without having even seen the original event sequence?
How does our prior knowledge affect our episodic recall?
Future goal
incorporate effect of prior knowledge into wisdom of crowds analysis

4. Experiments Materials Experiment 1 (Prior knowledge)
Type I: 3 videos with stereotyped event sequences (e.g. wedding)
Type II: 3 videos with less predictable event sequence
Extracted 10 images for testing
Experiment 1 (Prior knowledge)
16 subjects
No study sequence; main task is to order 10 images in as natural order as possible
Experiment 2a (Serial Recall)
28 subjects
Study video sequence followed by ordering task where subjects order 10 images as best as possible
Experiment 2b (Serial Recall)
in progress
Same as Experiment 2a but now study sequence is a series of still images

5. Bus Sequence: Raw Data prior serial recall
Note: first row is subject id, second row is Kendall tau to true ordering

6. Morning: Raw Data
prior
serial recall

7. Wedding: Raw Data
prior
serial recall

8. Yogurt: Raw Data
prior
serial recall

9. Pizza: Raw Data
prior
serial recall

10. Clay: Raw Data
prior
serial recall

11. Distribution of tau distances
Type I
(“informative prior”)
Type 2
(“uninformative prior”)
Note: bin width is two so first bar is the relative proportion to tau = 0 and tau = 1

12. E B C H F G A I J D 1 2 3 4 5 6 7 8 9 10 B A D C F E H G J I Prior
Serial Recall
10%
30%
50%
70%
90%
% of Participants Picking Position E B C H F G A I J D 1 2 3 4 5 6 7 8 9 10 B A D C F E H G J I

13. Median tau to truth
Note: the mean tau expected for random sequences is 22.5 (=10*9/4)

14. Type I
Type 2
Note: bin width is two so first bar is the relative proportion to tau = 0 and tau = 1

15. Wisdom of Crowds Analysis

16. Thurstonian Model

17. Thurstonian Model

18. Modified Perturbation Model
Original order A B C D E F G H
probability for individual j that the item at the source position i gets perturbed to the destination position k. D
Recalled order
Assumptions: individuals as well as items vary in perturbation noise levels

19. Modified Perturbation Model

20. Perturbation Model

21. Perturbation Model

22. Results

23. Overall Results t
Mean