from social psychology to sociology - a physicist’s point of view katarzyna sznajd-weron institute...
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From social psychology to sociology - a physicist’s point of view
Katarzyna Sznajd-WeronInstitute of Theoretical PhysicsWrocław University
Praha, November 6, 2003
Plan
Can we explain global changes by microscopic models?
Can we treat people like particles?Examples of social experiments.Social psychology and sociology.A simple model.
Almost a century ago physicists asked the question:
Can phase transitions be explained by microscopic theory?
T
M
T*
ferromagnet paramagnet
Back to 1920 ...
Wilhelm Lenz proposed a very simple microscopic model of interacting spins.
0
1
,
J
ShSSJH
S
ii
jiji
i
Was it only hope?
i
ii
ii ShSSJH 1
Spontaneous magnetization cannot be explained using this model in its 1D version.
After two decadeshope became reality
Onsager showed that the 2D version of the model can explain the critical phase transition.
Very simple local interactions can lead to qualitative changes on the macroscopic scale.
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The hope outside Physics
Rapid changes on macroscopic scale appear
in various systems.
Mostly these changes are unexpected.
Usually there is no obvious reason for them.
Can we explain them in terms of microscopic
interactions like we did for physical systems?
People sometimes behave like particles
Conformity The Millgram experiment:
Obedience to Authority The Asch experiment:
peer pressure Social validation
Stanley Milgram (1973) Journal of Abnormal and Social Psychology
volts learner experimenter
90 Ou! Please continue
105 Ou! (lauder) It is essential that we continue....
120 Ou! It hurts! Continue, it’s necessary
135 Ou! It is really painful The experiment requires that you go on until he has learned all the word pairs correctly
150 Let me leave! My heart ...
You have no other choice
What will happen? – ask psychiatrists and psychologists
Predicted: most subjects would not go beyond 150 volts, when the victim makes his first explicit demand to be freed.
Only 4% would reach 300 volts.
Only a pathological fringe of about 0.1% would use the highest shock on the board.
Solomon E. Asch - a pioneer of social psychology
Solomon E. Asch, born in Warsaw in 1907, he came to the United States in 1920 and received a Ph.D. from Columbia University in 1932.
Experiment of conformity (without Authority), 1956
Asch(1951-1955) – the experiment on visual perception?
The experimenter asks to choose which of the three lines on the left matches the length of the one on the right.
Results of the Asch experiment: social pressure
76% conformed to the majority at least once.
Conformity became more frequent as group size increased.
“The tendency to conformity in our society is so strong that reasonably intelligent (...) people are willing to call white black” /Asch/
There are some limits ...
1 2 3 4 5 6 7 8 9 100%
10%
20%
30%
40%
Number of people against
Mis
take
s
The power of social validation
Milgram, Bickman & Berkowitz, 1969
Results of experiments: 1 4%, 5 80%
Robert B. Cialdini: Social Validation –
the fundamental way of decision making
From social psychology to sociology
Social PsychologyFundamental unit:A person(micro scale)
SociologyFundamental unit:A social group(macro scale)
Social opinion
Sociologists ask if it will be better in the future?
09.97 06.98 04.99 02.00
-0.5
0
0.5
Time
YE
S-N
O
Social Norm: The ratio between breast and waist (Vogue)
1910 1930 1950 1970 1990
1.2
1.4
1.6
1.8
2B
W
B/W
Year
78/60
100/60
From micro to macro scale ...
Person = Spin (element of the system)Social validation = interaction between
elementsSocial opinion = magnetization
What to do if you do not know what to do ...
Whatever (financial market)
Nothing (Stauffer et al.)
„United we stand divided we fall” (original rule)
0 20 40 60 80 100 1200
2
4
6
8
10
12
14
time interval (100 MCS)
num
ber
of d
ecis
ion
chan
ges
We follow one person ...
100
101
102
103
10-4
10-2
100
102
P(
)
simulationspowerfit -1.5
Characteristic time of opinion change does not exist!
100
101
102
10310
0
102
104
106
108
Waiting time
Dis
trib
utio
n
What happens if we sometimes turn off the auto-pilot?
121
1
1 ,1
iiii
p
ii SSSSSS
There is some external field in every social system
For h=1h
1
-1
Advertising: with probability |h| buy product sgn(h).
0 0.2 0.4 0.6 0.8 1Power of advertisement (h)
Pro
babi
lity
of “
conq
uerin
g”
the
mar
ket
0
0.2
0.4
0.6
0.8
1
c0=0.05
c0=0.15
c0=0.25
Who wins ?
Generalized model - two components (TC)
Dynamics - the information flows outwardsDisagreement function - the change of
spins is controlled by function, which locally is minimized:
11211 iiii SSJSSJF
Phase I(1,2,3,4)
Phase 3(5,6)
Pha
se 2
(1)
Pha
se 4
(2)
-1 0 1 J1
1
J2 0
-1
1 2
3 4
5 6
Phase diagram for 2D TC model
Local agreement – global disagreement
0 500 1000 1500 2000 2500 3000-6
-5.5
-5
-4.5
-4
-3.5
-3
-2.5
-2
-1.5
time (MCS)
disa
gree
men
t fun
ctio
n