Privacy concerns and information disclosure: An illusion of control hypothesis
Laura Brandimarte and Alessandro Acquisti – Carnegie Mellon University
-I've never looked through a keyhole without finding someone was looking back.
-- Judy Garland, actress --Relying on the government to protect your privacy is like asking a peeping tom to install your
window blinds.
-- John Perry Barlow, founder of the Electronic Frontier Foundation --
Possible explanations
• Rational cost benefit analysis (Posner, 1978; Stigler, 1980)
• Awareness (Samuelson, 2001)
• Trust (Culnan & Armstrong PUT YEAR)
• “Behavioral” explanations (Acquisti, 2004)
– Prospect theory (Kahneman & Tversky, 1979) and
optimism bias
– Hyperbolic time discounting and Immediate gratification
We suggest one concurrent explanation:
“ILLUSION OF CONTROL”
Control over information dissemination does not necessarily
imply control over information access/usage. Still, people may
conflate the two concepts or they may give more importance
to control over dissemination of private information than to
control over access/use of that information by others,
resulting in “too much” disclosure
• Dependent variables
– Response rate (whether subject answered or not)
– Admission rate (whether subject admitted to some
behaviors)
• Explanatory variables
– Treatment
– Intrusiveness
– Demographics (age, gender)
40.0%
Others cheated
Instructor
Rate program
Competitive
Hours studying
Job
Instructor
Rate program
Competitive
Hours studying
Job
Cheated at school
Courses
Program
Move out
Roommates
Accommodation
Cheated on partner
Girlfriend
Married
See family
Family
Spare time
Friends elsewhere
Friends at CMU?
Friends
Which group
Group
Rate facilities
Sport on campus
Which sport
Sport
Happy
Like the city
How long in Pitt
On FB
Phone #
Address
Email
PoB
DoB
0.0%
Others cheated
Hypothesis: Loss of control over publication should decrease
willingness to disclose private information, and especially so
for the most sensitive questions: It is not the publication of
private information per se that disturbs people, but the fact
that someone else will publish it for them
20.0%
Last Name
Treatment group
“No question/field is required. The answers you provide will be
collected by the researcher, who will create a profile for you
and publish it on a new CMU networking website, which will
only be accessible by members of the CMU community,
starting from the end of April. The data will not be used in any
other way.”
Response rate for each question – Study 2
100.0%
80.0%
Treatment group
“The information you provide will appear on a profile that will
be automatically created for you. Half of the profiles created
for the participants will be randomly picked to be published on
a new CMU networking website, which will only be accessible
by members of the CMU community, starting at the end of this
semester. The data will not be used in any other way. NO
QUESTION/FIELD REQUIRES AN ANSWER.”
Hypothesis: Loss of control over publication should decrease
willingness to disclose private information even though,
statistically, the probability of third parties accessing/using it is
halved in the treatment condition
20.0%
Cheated at school
Courses
Program
Move out
Roommates
Accommodation
Cheated on partner
Girlfriend
Married
See family
Family
Spare time
Friends elsewhere
Friends at CMU?
Friends
Which group
Group
Rate facilities
Sport on campus
Which sport
Sport
Happy
Like the city
How long in Pitt
On FB
0.0%
Phone #
Control group
“The information you provide will appear on a profile that will
be automatically created for you. The profile will be published
on a new CMU networking website, which will only be
accessible by members of the CMU community, starting at the
end of this semester. The data will not be used in any other
way. NO QUESTION/FIELD REQUIRES AN ANSWER.”
40.0%
Address
Study 2: Profile automatically published vs. profile published
with 50% probability
60.0%
Email
• Questions focus on students’ life on and off campus:
multiple choice, Yes/No, Rating and open-end questions;
include quasi-identifiers + privacy intrusive and nonintrusive questions as rated by subjects independently in a
pre-study
60.0%
PoB
• Justification for the survey: creation of a university
networking website
80.0%
Age
• Complete online survey
100.0%
DoB
Design
• Subjects: students of Carnegie Mellon University recruited
on campus
Response rate for each question – Study 1
Gender
Our approach: do people respond to manipulations of control
over publication of information, even if accessibility/usage
don’t change – or indeed decrease?
If our hypothesis is correct, we should observe larger
willingness to reveal when subjects have control over
publication.
Control group
“No question/field is required. With the answers you provide,
a profile will be automatically created for you, with no
intervention by the researcher, and published on a new CMU
networking website, which will only be accessible by members
of the CMU community, starting from the end of April. The
data will not be used in any other way.”
First Name
Possible consequences
• Positive
– Signaling
– Self-representation
– Socialization
• But also negative
– Stalking (and cyber-stalking)
– Identity theft
– Price discrimination
– Lost employment opportunities
– …
• Study 2: survey-based randomized experiment, manipulating
control over probability of publication of personal
information
Study 1: Profile automatically created vs. profile created by
researcher
Last Name
According to a survey by the Pew Internet & American Life
Project, April 2007, about the use of online social networks by
teenagers:
• 82% of surveyed profile creators posted their first name
online and 29% also posted their last name (11% on publicly
accessible profiles);
• 79% included pictures of themselves;
• 61% published the name of their city or town;
• 29% posted their email address and 2% added a mobile
number.
Two studies:
• Study 1: survey-based randomized experiment, manipulating
control over mediated or unmediated publication of
personal information
First Name
Motivation
Attitudes/behavior dichotomy: even though people seem to
be very concerned about privacy violations, they reveal a lot
of private information, especially on the internet.
Example: online social networks
Expected Results
• Control over publication leads to more revelation of private
information, especially for privacy intrusive questions
• Control leads to admit more to some sensitive behaviors
• People seem to care more for control over publication of
private information than for control over access and use of
that information
• When someone other than themselves is responsible for the
publication, or when the publication itself becomes
uncertain – which reduces the probability of access/use by
others – people refrain from disclosing
• Results from a pilot study confirm these hypotheses