2016 Nov. The 8th International Conference on Social Informatics (SocInfo) Preprint: https://arxiv.org/abs/1611.02419

1. Lightweight Interactions
for Reciprocal Cooperation
in a Social Network Game
2016 Nov. The 8th International Conference on Social Informatics (SocInfo)
CyberAgent, Inc. All Rights Reserved
CyberAgent, Inc.
Akihabara Laboratory
Masanori Takano & Ichiro Fukuda
1

2. 2
Reciprocity
One of the mechanisms for cooperation.
• This mechanism drives interaction between cooperators.
Reciprocal individuals cooperate to others,
if the reciprocal individuals think that
these others also cooperate to the individuals.
• If reciprocal individuals think each other that
other individuals are also reciprocal
→ they construct stable reciprocal relationships.

3. 3
Cooperation in Initial Meeting: Evidences
3
How do reciprocal cooperators construct stable relationships?
• Cooperation in initial meetings
• Repaying cooperation from others (reciprocity)
A
B
C
D
D
D
D
D
D
D
A
B
C
C
C
C
C
C
C
C
If the individuals don't cooperate
→ they don't construct reciprocal
relationships.
If the individuals cooperate
→ they construct reciprocal
relationships.
In initial meetings of reciprocal individuals,
Actually, humans tend to cooperate each other in initial meetings
without prior interaction on experimental studies.
e.g., Rand et. al. [2011], Grujić et. al. [2012], Wang et. al. [2012], Peysakhovich and Rand [2013]
[Axelrod, 2006] (Theoretical work)
C: Cooperate
D: Defect

4. 4
Risk of Initial Meeting
4
In the real world, we don't cooperate each other without prior
interaction.
Because, in initial meeting, we cannot know others' cooperativeness.
→ We have large risks in initial interactions.
Others may be exploiters.
Therefore, we do observing, greeting, and talking (i.e., doing
lightweight interaction), and then we will construct social
relationships.

5. 5
Purpose and Approach
How do humans behave in initial
meetings to construct
reciprocal relationships?
We analyzed players' behavior based on
the data of a social network game
(SNG).

6. 6
Why Social Networking Games (SNG) ?
The data analysis of the game data catch up other approaches.
• We can observe detail behavior data of massive players like
mathematical models and simulations.
• The data is more detail than observation studies.
• The game environment is more open-ended than others.
• We know players' benefits as their scores.
Mathematical Model
Simulation
Experiments
in Lab
✊ ✋
Data Analysis of SNGs
Observation
Study
Partial and Biased Data
Hard to Understand
Clean and Detailed Data
Easy to Understand

7. 7
Social Network Game
URL: h$p://vcard.ameba.jp
Lang: Japanese
Since: 2012/10
Type: Raid Ba$le
We analyzed this game data for 2 weeks (2013/3/25∼2013/4/8)

8. 8
Basic Specification of the SNG
Players' Goal
• Getting points and rising a ranking based on the
points
Group and Migration
• Each player belonged to a group（The group size: 1〜50 players）
• A player can migrate from a group to another
group at any time.
Communication
• Players communicate by using simple messaging
functions.
• Messaging almost doesn't generate benefits and costs
of players.
1: Smith（12040pt）
2: Martin（11010pt）
3: Anderson（11005pt）
4: Ken（9015pt）
・・・
Migration
Simple messaging
Cooperation

9. 9
Cooperation
We focus on a specific game situation like Leader game
• In the SNG, players behave variously.
• We cannot track all cooperative behavior.
a player's this cooperation frequency in the SNG
≒ the player's cooperativeness
• Payoff Matrix of the situation like Snowdrift game
Cooperate Defect
Cooperate
-, - 1, 3
Defect
3, 1 0, 0
Cooperator get 1 point.
Defector get 3 point.

10. 10
Focus
Initial Interactions between newcomers and
existing group members
・Newcomers: migrants within 48 hours
• Can newcomers construct reciprocal relationships
with existing members?
• How do lightweight communication (messaging)
affect to construct reciprocal relationships?

11. 11
Reciprocity: Newcomer vs. Existing Members
Effect of players' cooperative behavior and messaging
for cooperation from others
Number of Cooperation
from others Number of Cooperation to Others
Number of Messaging to Others
Covariates for Control
Response Variable Explanatory Variable
Number of Cooperation to Others
Number of Messaging to Others
Newcomers'
Existing Group Members'
Cooperation
Cooperation &Messaging
Newcomer flag

12. 12
Reciprocity: Newcomer vs. Existing Members
Players tended to cooperate with newcomers.
Number of Cooperation
from others Number of Cooperation to Others
Number of Messaging to Others
Covariates for Control
Response Variable Explanatory Variable
Number of Cooperation to Others
Number of Messaging to Others
Newcomers'
Existing Group Members'
Cooperation
Cooperation &Messaging
Newcomer flag > 0

13. 13
Results: Reciprocity
Cooperation positively affected cooperation from others
Newcomers' cooperation effects are larger than existing members
Number of Cooperation
from others
Response Variable
Cooperation
Cooperation &Messaging
Number of Cooperation to Others
Number of Messaging to Others
Covariates for Control
Explanatory Variable
Number of Cooperation to Others
Number of Messaging to Others
Existing Group Members'
Newcomer flag
> 0
> 0
Newcomers'

14. 14
Results: Lightweight Interaction
Messaging also positively affected cooperation from others.
Newcomers' messaging effects are larger than existing members.
Number of Cooperation
from others
Response Variable
Cooperation
Cooperation &Messaging
Number of Cooperation to Others
Number of Messaging to Others
Covariates for Control
Explanatory Variable
Number of Cooperation to Others
Number of Messaging to Others
Existing Group Members'
Newcomer flag
> 0
> 0
Newcomers'

15. 15
Results: Lightweight Interaction
Messaging also positively affected cooperation from others.
Newcomers' messaging effects are larger than existing members.
Number of Cooperation
from others
Number of Cooperation to Others
Number of Messaging to Others
Covariates for Control
Response Variable Explanatory Variable
Number of Cooperation to Others
Number of Messaging to Others
Newcomers'
Existing Group Members'
> 0
> 0
This messaging doesn't have explicit
meanings, benefits, and costs in the SNG.
Nevertheless, it contributed to construct
reciprocal relationships
Hypothesis:
Messaging may explain the senders'
cooperativeness.

16. 16
Messaging as a Signal of Cooperativeness
Did players' messaging explain their cooperativeness?
Number of Cooperation
to others
Number of Messaging to Others
Covariates for Control
Response Variable Explanatory Variable
Number of Messaging to Others
Newcomers'
Existing Group Members'
Cooperation
Messaging

17. 17
Results: Messaging as a Signal of Cooperativeness
Messaging also positively explained cooperativeness .
Newcomers' this tendency was stronger than existing members.
Number of Cooperation
to others
Number of Messaging to Others
Covariates for Control
Response Variable Explanatory Variable
Number of Messaging to Others
Newcomers'
Existing Group Members'
> 0
> 0Cooperation
Messaging

18. 18
Summary
Newcomers and group members constructed reciprocal
relationships.
→ The players resolved initial interaction risks.
Cooperation in Initial Meetings
• Players in new relationships tend to cooperate more than players in
known relationships.
Lightweight communications (messaging)
• It supported constructions of reciprocal relationships.
• It explained players' cooperativeness.
• Especially, it is important in initial meetings.
→ This may be employed to increase senders' likelihood of
cooperativeness in risky situations.