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(Un)informed Consent: Studying GDPR Consent Notices in the Field

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Abstract and Figures

After the adoption of the General Data Protection Regulation (GDPR) in May 2018, more than 60 % of popular websites in Europe were found to display a cookie consent notice. This has quickly led to users becoming fatigued with privacy notifications and contributed to the rise of both browser extensions that block these banners and demands for a solution that bundles consent across multiple websites or in the browser. In this work, we identify common properties of the graphical user interface of consent notices and conduct three studies with more than 80,000 unique users on a German website to investigate their influence on consent. We find that users are more likely to interact with a notice shown in the lower (left) part of the screen. Given a binary choice, more users are willing to accept tracking compared to mechanisms that require them to allow cookie use for each category or company individually. We also show that the practice of nudging is widely used and has a large effect on the choices users make. Our studies have implications for future regulations and the design of consent notices that encourage users to actively make an informed choice.
Content may be subject to copyright.
(Un)informed Consent: Studying GDPR Consent Notices in the
Field
Christine Utz
Ruhr-Universität Bochum
Bochum, Germany
christine.utz@rub.de
Martin Degeling
Ruhr-Universität Bochum
Bochum, Germany
martin.degeling@rub.de
Sascha Fahl
Ruhr-Universität Bochum
Bochum, Germany
sascha.fahl@rub.de
Florian Schaub
University of Michigan
Ann Arbor, Michigan
fschaub@umich.edu
Thorsten Holz
Ruhr-Universität Bochum
Bochum, Germany
thorsten.holz@rub.de
ABSTRACT
Since the adoption of the General Data Protection Regulation (GDPR)
in May 2018 more than 60 % of popular websites in Europe display
cookie consent notices to their visitors. This has quickly led to users
becoming fatigued with privacy notications and contributed to
the rise of both browser extensions that block these banners and de-
mands for a solution that bundles consent across multiple websites
or in the browser. In this work, we identify common properties of
the graphical user interface of consent notices and conduct three
experiments with more than 80,000 unique users on a German web-
site to investigate the inuence of notice position, type of choice,
and content framing on consent. We nd that users are more likely
to interact with a notice shown in the lower (left) part of the screen.
Given a binary choice, more users are willing to accept tracking
compared to mechanisms that require them to allow cookie use for
each category or company individually. We also show that the wide-
spread practice of nudging has a large eect on the choices users
make. Our experiments show that seemingly small implementation
decisions can substantially impact whether and how people inter-
act with consent notices. Our ndings demonstrate the importance
for regulation to not just require consent, but also provide clear
requirements or guidance for how this consent has to be obtained
in order to ensure that users can make free and informed choices.
CCS CONCEPTS
Security and privacy Usability in security and privacy
;
Human-centered computing
Empirical studies in interac-
tion design;
Social and professional topics
Governmental
regulations.
KEYWORDS
consent; notications; usable privacy; GDPR
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For all other uses, contact the owner/author(s).
CCS ’19, November 11–15, 2019, London, United Kingdom
©2019 Copyright held by the owner/author(s).
ACM ISBN 978-1-4503-6747-9/19/11.
https://doi.org/10.1145/3319535.3354212
ACM Reference Format:
Christine Utz, Martin Degeling, Sascha Fahl, Florian Schaub, and Thorsten
Holz. 2019. (Un)informed Consent: Studying GDPR Consent Notices in the
Field. In 2019 ACM SIGSAC Conference on Computer and Communications
Security (CCS ’19), November 11–15, 2019, London, United Kingdom. ACM,
New York, NY, USA, 18 pages. https://doi.org/10.1145/3319535.3354212
1 INTRODUCTION
In recent years, we have seen worldwide eorts to create or update
privacy laws that address the challenges posed by pervasive com-
puting and the “data economy”. Examples include the European
Union’s General Data Protection Regulation (GDPR) [
46
], which
went into eect on May 25, 2018, and the California Consumer Pri-
vacy Act (CCPA) [
42
], which becomes eective on January 1, 2020.
These laws uphold informational self-determination by increasing
transparency requirements for companies’ data collection practices
and strengthening individuals’ rights regarding their personal data.
The GDPR’s impact was twofold. While the number of third-
party services on European websites barely changed [
41
], websites
now ask users for consent prior to setting cookies. In mid-2018,
about 62 % of popular websites in the EU were found to display
a(cookie) consent notice, often referred to as “cookie banner,” and
in some countries an increase of up to 45 percentage points since
January 2018 was observed [
12
]. The design and complexity of
such consent notices greatly vary: Some merely state that the web-
site uses cookies without providing any details or options, while
others allow visitors to individually (de)select each third-party ser-
vice used by the website. Paired with the fact that consent notices
often cover parts of the website’s main content, this high preva-
lence has led website visitors to become fatigued with consent
mechanisms [
8
]. Consequently, tools have emerged that provide
pragmatic workarounds — one example is the “I don’t care about
cookies” browser extension [21]. But oftentimes this only leads to
data collection taking place without consent since the default on
many websites is to employ user tracking unless the visitor has
opted out [
17
], and 80 % of popular EU websites do not oer any
type of opt-out at all [12].
Instead of adopting opt-in solutions or enforcing the existing Do-
Not-Track standard, the online advertising industry has developed
a consent framework [
14
] to reduce the number of consent requests.
Notices using this framework ask website visitors if they consent to
data collection for dierent purposes by up to 400 listed third-party
advertisers. Information about their consent decision is then passed
down the online advertising supply chain.
Overall, consent notices have become ubiquitous but most pro-
vide too few or too many options, leaving people with the impres-
sion that their choices are not meaningful and fueling the habit
to click any interaction element that causes the notice to go away
instead of actively engaging with it and making an informed choice.
Most notice designs only partially use the available design space
for consent notices. But we have also seen notices that, e. g., do not
force users to accept cookies, ask for consent without hidden pre-
selections, or provide visitors with granular yet easy-to-grasp mech-
anisms to control the website’s data processing practices. Hence,
we expect that how a consent notice asks for consent has a large
impact on how website visitors interact with it, and we are positive
that there are design decisions that better motivate people to inter-
act with consent notices in a meaningful way instead of annoying
them.
In this paper, we systematically study design properties of ex-
isting consent notices and their eects on consent behavior. We
systematize consent notices using a sample of 1,000 notices col-
lected from live websites and identify common variables of their
user interfaces.
Our research goal is to explore the design space for consent
notices to learn how to encourage website visitors to interact with
a notice and make an active, meaningful choice. Over the course of
four months, we conduct a between-subjects study with 82,890 real
website visitors of a German e-commerce website and investigate
their (non-)interaction with variants of consent notices. We collect
passive clickstream data to determine how users interact with con-
sent notices and invite them to participate in a voluntary follow-up
online survey to obtain qualitative feedback. The study comprises
three distinct eld experiments to answer the following research
questions:
(1)
Does the position of a cookie consent notice on a website
inuence visitors’ consent decisions? (Experiment 1, n =
14,135)
(2)
Do the number of choices and nudging via emphasis / pre-
selection inuence users’ decisions when facing cookie con-
sent notices? (Experiment 2, n = 36,530)
(3)
Does the presence of a privacy policy link or the use of tech-
nical / non-technical language (“this website uses cookies”
vs. “this website collects your data”) inuence users’ consent
decisions? (Experiment 3, n = 32,225)
In a short follow-up survey answered by more than 100 partici-
pants, we ask website visitors to voluntarily report the motivation
for their selection, how they perceive the notice they have seen,
and how they expect consent notices to function in general.
We nd that visitors are most likely to interact with consent
notices placed at the bottom (left) position in the browser window
while bars at the top of the screen yielded the lowest interaction
rates. This is mainly due to the (un)importance of the website con-
tent obstructed by the notices and suggests taking into account
characteristics of the individual website to identify the notice po-
sition most likely to encourage user interaction. Interaction rates
were higher with notices that provided at most two options com-
pared to those that let users (de)activate data collection for dierent
purposes or third parties individually, even though those notices do
not allow visitors to express consent freely. We also show that the
more choices are oered in a notice, the more likely visitors were
to decline the use of cookies. This underlines the importance of
nding the right balance between providing enough detail to make
people aware of a website’s data collection practices and not over-
whelming them with too many options. At the same time, nudging
visitors to accept privacy-invasive defaults leads more visitors to
accept cookies, whereas in a privacy-by-default (opt-in) setting,
less than 0.1 % of visitors allow cookies to be set for all purposes.
This suggests that the current data-driven business models of many
webservices, who often employ dark patterns to make people con-
sent to data collection, may no longer be sustainable if the GDPR’s
data protection by default principle is enforced. Technical language
(“This site uses cookies” instead of “This site collects your data”)
appears to yield higher interaction rates with the consent notice
but decreases the chance that users allow cookie use. We nd that
the presence of a link to the site’s privacy policy does not increase
user interaction, underlining the importance of making information
immediately actionable rather than pointing to further resources.
Survey feedback indicates that users favor category-based choices
over a vendor-based approach, and they expressed a desire for a
transparent mechanism. A common motivation to give consent is
the assumption that the website cannot be accessed otherwise.
Based on the results of our eld study, we conclude that opt-out
consent banners are unlikely to produce intentional/meaningful
consent expression. We therefore recommend that websites oer
opt-in notices based on categories of purposes. Above all, we ob-
served that the majority of website visitors does not accept cookies
for all purposes, and feedback from our survey suggests that a uni-
ed solution that does not interfere with every single website yet
provides more control than a simple yes–no decision would best t
users’ needs.
2 CONSENT NOTICES
We rst describe the legal background of consent notices and cur-
rent challenges for their practical implementation. Then we identify
and analyze variables of the graphical user interface of commonly
used types of consent notices.
2.1 Background
Cookie consent notices emerged in the wake of the European
Union’s Directive 2009/136/EC [
45
]. The directive changed Article
5(3) of the ePrivacy Directive (2002/58/EC) [
44
] to require that data
is stored on users’ devices only after having obtained user consent
based on “clear and comprehensive information [...] about the pur-
poses of the processing.An exemption to this consent requirement
is storing of information that is “strictly necessary,such as session
or authentication cookies.
On May 25, 2018, the European Union’s General Data Protection
Regulation (GDPR; Regulation (EU) 2016/679) went into eect. Its
Article 6 contains six legal bases for the processing of personal
data of European residents, including that “the data subject has
given consent to the processing of his or her personal data for one
or more specic purposes”. Recital 32 of the GDPR and guidelines
published by EU data protection authorities [
6
] require for valid
consent “a clear armative act” that is a “freely given, [purpose-
]specic, informed and unambiguous indication of [...] agreement
to the processing of personal data.Another document claries the
relationship between the ePrivacy Directive (2002/58/EC) and the
GDPR for the use of cookies: Article 5(3) of the directive governs
access to non-necessary cookies in the user’s browser, whether it
contains personal data or not, while the GDPR applies to subsequent
processing of personal data retrieved via cookies [15].
Degeling et al. found that after the GDPR went into eect 62.1 %
of 6,579 popular websites in Europe displayed cookie consent no-
tices, compared to 46.1 % in January 2018 [12].
This high prevalence has sparked eorts to reduce the number
of consents required. The most widely used solution, supported
by the online advertising industry, is the Transparency & Consent
Framework by IAB Europe [
14
]. This framework has been criti-
cized for its bundling of purposes [
36
] and a lack of transparency
regarding the parties the website visitor’s personal data could be
shared with [
12
,
36
]. An October 2018 decision by the French data
protection authority CNIL [
11
] pointed out a lack of consent ver-
ication in the framework, and in April 2019 a formal complaint
was led against the IAB for showing a consent notice on its own
website that forces visitors to consent if they want to access the
website [37], which is not allowed under GDPR.
Another suggestion to decrease the number of consent prompts
is to move consent decisions to the browser and let users locally
specify their data collection preferences [
31
]. The browser then
sends adequate signals to the websites requesting data collection.
This would require websites to respect the opt-out signals requested
by the browser — something that has not worked out in the past
with the Do-Not-Track standard [29].
2.2 Properties of Consent Notices
Consent notices currently found on websites vary both in terms of
their user interface and their underlying functionality. Regarding
the latter, Degeling et al. identied distinct groups within existing
implementations of consent notices [
12
]. Some are only capable
of displaying a notication that the website uses cookies or col-
lects user data without providing any functionality to make the
website comply with the visitor’s choice. In contrast, other cookie
notices are provided by third-party services that oer complex
opt-in choices and block cookies until the user consents explicitly.
Our study focuses on the user interface of consent notices, a
topic which has not been systematically studied before. In order
to identify common properties of consent notices currently used
on websites, we analyze a random sample of 1,000 notices drawn
from a set of 5,087 we collected in a previous study [
12
]. To obtain
that set, the following steps were taken: First we created a list of
websites containing the 500 most popular websites for each member
state of the European Union as identied by the ranking service
Alexa [
4
]. This yielded a list of more than 6,000 unique domains.
Using a Selenium-based automated browser setup, we visited all of
them in an automated way in August 2018 from an IP address within
the EU and took screenshots of each website’s home page. We then
manually inspected these screenshots if they contained a consent
notice. In our previous study, we identied six distinct types of
choices consent notices oer to website visitors, as described below.
In this work, we extend our prior analysis to other variables of the
graphical user interface of consent notices. For this, we took the
5,087 consent notices collected previously, drew a random sample
of 1,000 notices, and manually inspected how they diered in their
graphical user interface. We identied the following eight variables,
whose possible values, along with their frequency in our random
sample, are listed in Table 1:
Size.
The size of the consent notice as displayed in the browser.
We found the value of this variable to vary widely depending on
the implementation of the notice, from small boxes that only cover
a fraction of the viewport to notices taking up the whole screen.
Responsive web design may result in the same notice using up
dierent shares of the viewport, depending on the screen size and
orientation of the device used to view the website. Typically notices
take up a larger percentage of the viewport on smartphones than
on desktop computers and tablets. The size of a consent notice may
also be xed by design, i. e., to cover the whole viewport of any
device.
Position.
We observed the consent notices in our dataset to be
displayed in seven distinct positions: in one of the four corners
of the viewport (dialog style; 6.9 %), at the top (27.0 %) or bottom
(57.9 %) like a website header or footer (bar style), and vertically
and horizontally centered in the middle of the viewport (7.8 %)).
On smartphones in portrait mode, the limited space reduces the
number of options to the top, bottom, and middle of the screen.
Blocking.
Some consent notices (7.0 %) prevent visitors from in-
teracting with the underlying website before a decision is made [
39
].
The site’s content may also be blurred out or dimmed [
17
]. All con-
sent notices shown in the center position were blocking. We also
observed some blocking consent notices at the top or bottom posi-
tion.
Choices.
Consent notices oer website visitors dierent choice
options. We identied the following mechanisms for user interac-
tion [12]:
No option
notices simply inform the user that the website
uses cookies without any option for interaction. The user
continuing to use the website is interpreted as agreement to
the notice.
Conrmation-only
banners feature a button with an ar-
mative text such as “OK” or “I agree”, clicking on which is
interpreted as an expression of user consent.
Binary
notices provide two buttons to either accept or de-
cline the use of all cookies on the website.
Category
-based notices group the website’s cookies into
a varying number of categories. Visitors can allow or dis-
allow cookies for each category individually, typically by
(un)checking a checkbox or toggling a switch. For trans-
parency reasons, the category of “strictly necessary” cookies
(whose use does not require consent according to Article 5(3)
of Directive 2002/28/EC) is often also listed but the switch to
deactivate it is greyed out. Some notices use a
slider
: Instead
of (de)selecting categories individually the user can move a
slider to select one of the predened levels, which implies
consent to all of the previously listed categories.
Vendor
-based notices oer even more ne-grained control
by allowing visitors to accept or decline cookies for each
third-party service used by the website. Such notices are part
Table 1: Variables of the graphical user interface of consent notices and their values across a sample of 1,000 drawn from 5,087
consent notices collected from the most popular websites in the European Union in August 2018
Position Choices (visible) Choices (hidden) Blocking Nudging
top 27.0 % no option 27.8 % no option 26.3 % yes 7.0 % yes 57.4 %
bottom 57.9 % conrmation 68.0 % conrmation 59.9 % no 93.0 % no 14.8 %
top right 0.2 % binary 3.2 % binary 4.0 % n/aa27.8 %
bottom right 3.0 % categories 1.0 % slider 0.2 %
top left 0 % vendors 0 % categories 8.1 %
bottom left 3.7 % vendors 1.1 %
center 7.8 % other 0.4 %
other 0.4 %
Link to privacy policy Text: Collection Text: Processor Text: Purposes
yes 92.3 % “cookies” 94.8 % unspecied 75.5 % generic 45.5 %
no 6.6 % “data” 1.4 % rst party 0.7 % specic 38.6 %
other 1.1 % both 1.6 % third party 2.6 & none 16.9 %
none 0.9 % b oth 21.1 %
other 1.3 % other 0.1 %
aNudging is not available for “no option” notices.
of IAB Europe’s Transparency and Consent Framework [
14
],
which refers to its advertising partners as “vendors.
Text.
The text displayed by consent notices also varies widely.
It should inform the website visitor of the fact that the website
uses cookies or similar tracking technology and may list additional
information such as the purpose of the data collection. Depending
on the choices oered, the notice may provide instructions for
consenting to (or denying) the use of cookies. Table 1 provides
an overview of common text contents of consent notices for the
following typical pieces of information:
Collection.
What the visitor consents to, which can be the
use of cookies (94.8 %), the collection of their personal data
(1.4 %), both (1.6%), neither (0.9%), or something else (such
as the website’s privacy policy; 1.3 %).
Processor.
Who collects this information, which can be
specically limited to the rst party (0.7 %), third-party ser-
vices (2.6 %), both (21.1 %), or refer to an unspecied party
(usually denoted by the pronoun “we” or the domain/website
name; 75.5 %).
Purposes.
These may be specic (e. g., “audience measure-
ment” or “ad delivery”; 38.6 %), generic (e. g., “to improve
user experience”; 45.5 %), or not specied at all (16.9 %).
Nudging & Dark Patterns.
Consent notices often (57.4 %) use
interface design to steer website visitors towards accepting privacy-
unfriendly options. Typical techniques include color highlighting of
the button to accept privacy-unfriendly defaults, hiding advanced
settings behind hard to see links, and pre-selecting checkboxes that
activate data collection [
10
]. We observed all of these techniques
in our sample.
Formatting.
We found that, unless predetermined by the con-
sent library used, the choice of fonts and colors typically matched
that of the underlying website. The formatting of consent notices
may also be inuenced by the website’s business requirements [
17
],
e. g., sites relying on monetization via online behavioral advertis-
ing (OBA) are unlikely to steer their visitors towards an opt-out
mechanism by making this option highly visible.
Link to additional information.
Consent notices may include
a link to the website’s privacy policy, a designated cookie policy, or
a website providing additional information about cookies – 92.3 %
of the notices in our sample contain such a link to additional infor-
mation. In Table 1, we marked as “other” consent notices where the
full privacy policy was already included in the notice itself (1.1 %).
Table 1 shows that the majority of consent notices are placed at
the bottom of the screen (58 %), not blocking the interaction with
the website (93 %). They oer no options besides a conrmation
button that does not do anything (86 %), and most try to nudge users
towards consenting (57 %). While nearly all notices (92 %) contain
a link to a privacy policy, only a third (39%) mention the specic
purpose of the data collection or who can access the data (21 %).
3 METHOD
Given the legal requirements for explicit, informed consent, the
vast majority of cookie consent notices we analyzed are likely not
compliant with European privacy law. To further investigate the
eects of dierent combinations of these properties on consent
behavior, we conducted a eld study with consent notices on a
German e-commerce website.
We investigated the eect of the following parameters on users’
interactions with consent notices:
(1)
The position of the notice, as notices displayed in some parts
of the screen are more likely to be ignored.
(2)
The number of choices oered by the notice, which is in-
uenced by legal requirements and the need to give users
actual control over the website without overwhelming them
with too many options.
(3)
Nudging visitors towards giving consent through highlight-
ing and preselection, since this may cause people to consent
who would not have made the same decision otherwise.
(4)
The presence of a privacy policy link and whether the notice
refers to “cookie use” (technical language) or “data collec-
tion” (non-technical language). These dierences in wording
may inuence people’s expectations of the website’s data
processing practices and thus their consent decision.
We did not evaluate the eects of the following parameters:
blocking (because the owner of our partner website asked us not
to block access to the site), formatting (because of the multitude
of options – we chose the same color scheme as in the notice
previously used on the website), and size (which is dicult to vary
consistently across devices).
From the end of November 2018 to mid-March 2019, we con-
ducted three between-subjects experiments to determine if, and
how, dierent parameters of consent notices inuence interaction
rates. In each experiment, we tested variants for one or two of the
parameters described in Table 1: position in Experiment 1, choices
and nudging in Experiment 2, and wording and the presence of a pri-
vacy policy link in Experiment 3. The respective other parameters
were kept constant in an experiment.
3.1 Study Setup
We partnered with a German-language e-commerce website based
on WordPress. The website has 15,000–20,000 unique visitors per
month, most of which are single-page visitors that reach the site
from a search engine looking for product information and reviews.
The third-party services used by the website are Google Fonts and
the CSS framework Ionic for design, Google Analytics embedded via
Google Tag Manager for audience measurement, Facebook social
media buttons, embedded YouTube videos, and targeted advertise-
ments delivered by Google Ads. All of these services store cookies
in the visitor’s browser.
We modied a WordPress plugin, Ginger – EU Cookie Law [
26
],
to test dierent notice variants. Ginger was selected because it can
block cookies before opt-in, log users’ consent, and because it was
released under a GPLv2 license. By the time of publication of this
paper, the original version of the plugin had been discontinued. We
added support for checkbox-based and “no option” notices. We did
not implement “slider” notices because we considered them a less
compliant variant of the “categories” type.
The plugin was further modied to function as follows in our
study: When a user rst visited our partner website, they were
shown one consent notice. Which notice of the
n
test conditions
in the current experiment was displayed was determined in round-
robin fashion. The ID of the displayed notice was stored in a cookie
in the participant’s browser to ensure visitors who did not click
the notice would continue to see the same notice across subpages
and recurring visits. Each participant was assigned a unique iden-
tier:
pid=SHA-256(ip_address ||user_aдent )
. The participant’s IP
address was discarded after computation of
pid
. The participant
ID was stored in another cookie, together with the participant’s
consent as required by Article 7 GDPR1.
If the visitor clicked any interaction element that would usually
cause a consent notice to disappear, i.e., the ‘X’ discard button,
1
The legal bases for storing the cookie that remembers the banner ID are Article 6(1)(e)
GDPR (public interest in conducting this study) and Article 6(1)(c) GDPR (compliance
with a legal obligation) for storing the consent cookie.
“Accept,” “Decline,” or “Submit,”
2
the notice did not disappear in-
stantly. Instead, the notice content was replaced with an invitation
to take an online survey about their experiences with this and other
consent notices (see Appendix B). The invitation disclosed that
this was a university study and that participants could win one of
15 25-euro shopping vouchers. Users could either click “Discard”
to close the notice, or select “Participate” to open the survey in a
new browser tab. The survey was created in a LimeSurvey instance
running on a web server hosted by the authors.
If the website visitor did not interact with the consent notice, the
content of the notice was automatically replaced with the survey
invitation 30 seconds after the page had fully loaded. This is because
we also wanted to explore users’ reasons for not interacting with
consent notices. Web analytics data for our partner website showed
that 95 % of all users who had interacted with the website’s previous
consent notice had done so within 30 seconds of accessing the site.
Thus we assumed that website visitors who did not interact with
the consent notice within 30 seconds would not have clicked it at a
later point in time.
We modied the Ginger plugin’s logger add-on to create log
entries whenever a participant clicked an interaction element on the
notice. Log events were also triggered upon page load, when links to
the privacy policy or survey were clicked, when the consent notice
content was auto-replaced with the survey invitation, and when
the participant dismissed this invitation. Each log entry consisted
of a timestamp, the participant’s ID (
pid
), the ID of the consent
notice they had seen, the event they had triggered, their screen
resolution, operating system, browser, and whether an ad blocker
had been detected.3
3.2 Experiment 1: Position
Experiment 1 ran from November 30 to December 18, 2018, i. e., for
19 days. We had observed consent notices being shown at various
screen positions and wanted to determine the eect of placement
on interaction with the cookie consent notice to inform our subse-
quent experiments. The research question for Experiment 1 was:
Does the cookie consent notice’s position on a website inuence a
visitor’s consent decision? In order to encourage user interaction,
we displayed a “binary” notice without nudging (see Figure 1(bb)),
the simplest type oering an actual choice. We tested the notice in
six dierent positions (see Figure 2). We could not test the center
position as our partner asked us to not block access to their website.
3.3 Experiment 2: Number of Choices, Neutral
Presentation vs. Nudging
From December 19, 2018 to January 28, 2019, we conducted Ex-
periment 2, which focused on the eects of given choices and pre-
selections on consent. In our analysis of consent notices, we had
identied various complexity levels of choices oered and meth-
ods to emphasize certain options. Prior work has shown that the
2
In all experiments, all texts in the consent notice and survey were in German to
match the website’s language. Survey responses were also in German. The authors
translated all texts and responses into English for this paper. Both the original and the
translated consent notices and the survey are available in our GitHub repository at
https://github.com/RUB-SysSec/uninformed- consent.
3
We used BlockAdBlock 3.2.1 (https://github.com/sitexw/BlockAdBlock) to detect ad
blocking functionality in the visitor’s browser.
(b) No option
(d) Categories
(c) Conrmation
(e) Vendors
(aa) Binary, nudging
(bb) Binary, non-nudging
Figure 1: Cookie consent notices with dierent choice mechanisms and nudging used in our experiments: (a) a binary notice
in two variants, one nudging visitors to click “Accept” (aa) and one presenting both choices equally (bb); (b) a no-option notice
(nudging not applicable); (c) a conrmation-only notice (shown without nudging); (d) a category-based notice with pre-selected
checkboxes (nudging); and (e) a vendor-based notice with unchecked checkboxes (non-nudging).
top, “bar”
boom, “bar”
top le,
“dialog”
boom le,
“dialog”
top right,
“dialog”
boom
right,
“dialog”
Figure 2: Positions tested in Experiment 1.
design and architecture of choices heavily inuences people’s de-
cisions [
43
,
50
]. While this eect has also been shown successful
in improving user privacy [
1
,
2
], in practice it is most often used
to make users share more information [10]. Website owners often
have an interest in getting visitors to agree to the use of cookies
and hence highlight certain choices in the consent notice to nudge
visitors towards accepting. We observed this for 57.4 % of the no-
tices in our sample. Our research question therefore was: Does the
number of choices and nudging through emphasis or pre-selection in
consent notices inuence user’s consent decisions?
For nudging, we used pre-checked checkboxes and buttons high-
lighted in contrasting colors, techniques often used to nudge users
towards accepting default settings [
10
]. While we observed that
most category- and vendor-type notices in practice display such
ne-grained controls only after the visitor clicked “Settings,” we
chose to immediately display all available options to ensure that
our conditions only varied in the number and framing of choices.
In Experiment 2, we displayed the following consent notices at the
position determined in Experiment 1 to yield the highest interaction
rates:
No option
(Figure 1 (b)): In line with many notices we ob-
served, we added an ‘X’ in the top-right corner to dismiss
the banner. There is no nudging variant because the notice
does not oer any choice.
Conrmation–Non-nudging
(Figure 1 (c)): This notice
has an “Accept” button which is not highlighted.
Conrmation–Nudging
: Same as the Conrmation–Non-
nudging notice, but the “Accept” button is highlighted (like
the “Accept” button in Figure 1 (a) (aa)).
Binary–Non-nudging
(Figure 1 (a) (bb)): The “Accept” and
“Decline” buttons are formatted the same way, neither is
emphasized.
Binary–Nudging
(Figure 1 (a) (aa)): Same as Binary–Non-
nudging but only the “Accept” button is highlighted in a
contrasting color.
Categories–Non-nudging
: Same as notice (d) in Figure 1,
but with unchecked checkboxes. The “Necessary” category
cannot be unchecked, as is common practice.
Categories–Nudging
(Figure 1(d)): Same as Categories–
Non-nudging but with pre-checked checkboxes for all cate-
gories.
Vendors–Non-nudging
(Figure 1(e)): Similar to the cate-
gories variant, but the checkboxes correspond to the third-
party services used by our partner website.
Vendors–Nudging
: Same as Vendors–Non-nudging but with
pre-selected checkboxes.
For the category-based notices, we had to map the third-party
services used by the website to dierent categories. We manu-
ally inspected the 434 category-based notices in our initial set of
5,087 consent notices for common category wording. For example,
we found advertising cookies to be categorized as “marketing” or
“advertising”; web analytics was also referred to as “performance
cookies,” “statistics,” or “audience measurement.” This yielded the
following category–third party mappings:
Necessary: Cookies to remember the displayed notice and
the website visitor’s consent decision.
Personalization & Design: Ionic, Google Fonts
Analytics: Google Analytics
Social Media: Facebook, YouTube
Marketing: Google Ads
For all category- and vendor-based notices in Experiments 2 and
3, the available options were displayed in random order, except for
the “Necessary” category, which was always displayed rst as in
the majority of category-based notices we had observed.
In Experiments 2 and 3, we increased the font size of the banner
message, resulting in larger notices. We did this to x an imple-
mentation bug of the Ginger plugin that had caused the text to be
displayed in a very small font on some smartphones in portrait
mode.
3.4 Experiment 3: (Non-)Technical Language
and Privacy Policy Link
Experiment 3 was conducted from January 29 to March 15, 2019.
In this experiment, we tested the inuence of the presence of a
link to the website’s privacy policy. Previous research suggests that
(American) Internet users have consistent misconceptions about
privacy policies, indicated by the fact that a majority believes the
existence of a privacy policy means that a website cannot share
personal data with third parties [
47
]. At the same time, Martin [
27
]
showed that the existence of a reference to a privacy policy in the
context of data sharing explanations increases mistrust in a website.
There are further known misconceptions about what cookies actu-
ally are and what they are used for [
19
,
30
]. To learn more about
the inuence of these factors in the context of consent notices, our
research question was: Does the presence of a privacy policy link or
mention of cookies inuence users’ consent decisions?
The base notice for this experiment was the Category–Non-
nudging notice from Experiment 2 because of GDPR’s data pro-
tection by default requirement and the ability to provide consent
for specic purposes with checkboxes. We chose a category-based
notice over a vendor-based one due to the results of Experiment 2
(see Section 4.3). The notice text for this experiment was: “This
website [uses cookies | collects your data] to analyze your usage of
this site, to embed videos and social media, and to personalize the
ads you see. Please select for which purposes we are allowed to use
your data. [You can nd more information in our privacy policy].
We tested the following conditions:
Technical–PP Link:
The original Categories–Non-nudging
notice from Experiment 2. It uses both technical language
(“collects cookies”) and a sentence with a link to the website’s
privacy policy.
Technical–No PP Link:
Same as Technical–PP Link, but
the privacy policy sentence was replaced with whitespace
to keep the size of the notices consistent.
Non-Technical–PP Link:
Same as Technical–PP Link, but
using non-technical language (“your data” instead of “cook-
ies”).
Non-Technical–No PP Link:
Same as Non-Technical–PP
Link, but with the privacy policy sentence replaced with
whitespace.
For participants who saw a notice with non-technical language,
we replaced other occurrences of the term “cookie” in our setup:
In the study invitation, “cookie notice” was replaced with “privacy
notice,” and we adjusted the wording of some survey questions and
response options as described in Appendix B.
3.5 Research Ethics
Our study was conducted on a website with real users, which raises
ethical concerns as we did not ask for consent prior to measur-
ing their interactions with consent notices. We did so to ensure
ecological validity and be able to capture non-biased results as we
expected the majority of visitors to not pay attention to a study
consent notice asking them to opt in, which was supported by our
ndings.
While our institution does not require IRB review for minimal
risk studies, we ensured that we did not deceive or harm website
visitors and their privacy. All displayed consent notices functioned
as described and respected the visitor’s choice. To test the eect of
no-option consent notices, we had to oer fewer choices than we
believe is required by the GDPR. We added a paragraph describing
our study to the website’s privacy policy. The data we collected
was pseudonymized. Logs were stored on the website’s server and
access was limited to two researchers conducting the analysis and
the website’s owner. After the study, the data was removed from
the server and copied to the researchers’ data center.
All visitors were informed about the study after 30 seconds when
we showed a notice asking them for participation in the survey.
Survey participants were asked for explicit consent and to conrm
they were over 18 and wanted to participate. Email addresses of
participants who opted to participate in the prize draw were stored
separately from the dataset, without the participant ID.
3.6 Data Analysis
3.6.1 Event logs. When we started the data analysis, we noticed
inconsistencies in some entries. The event logs created by our plu-
gin indicated that some website visitors had seen multiple notice
versions. This could have happened because users had deactivated
cookies completely, visited the website in multiple sessions using
private browsing mode, or opened the website in multiple tabs si-
multaneously. For another set of users, we detected multiple screen
resolutions, mostly because the screen orientation had changed.
Rotating the screen could lead to the notice covering dierent
parts of the website, so we removed these participants to preserve
consistency. In total, we removed 2,1 % of participants across all
experiments.
3.6.2 Survey. We considered a survey response complete if the
participant had at least answered Q1–Q6 but did not provide a free-
text answer to Q7 and Q8. Due to a low survey response rate we
received few responses for some conditions. We therefore refrained
from a quantitative analysis of survey responses. In Section 4, we
evaluate responses to the open-ended questions (parts of Q1; Q6–
Q8). We coded these responses using emergent thematic coding.
Two of the authors independently devised a set of codes for each
question and coded the responses. The results were discussed and
yielded a nal codebook, which was used to re-code all responses.
Any remaining disagreements were reconciled by the two coders.
We report the codes and their distribution in Appendix B, along
with the answers to all closed-ended questions.
4 RESULTS
4.1 Dataset and Website Visitors
Our cleaned dataset contained event logs of 82,890 unique website
visitors: 14,135 in Experiment 1, 36,530 in Experiment 2, and 32,225
in Experiment 3. 21.72 % of all visitors accessed the website on a
desktop or laptop computer and 78.28 % with a mobile device (of
which 5.1 % were tablets)
4
. Overall, 6.95 % of participants used an
ad blocker. The rate was much higher on desktop (29.1%) than
on mobile devices (0.8 %). These numbers are consistent with a
2017 report for Germany [
35
], the highest rate of ad block users
in Western Europe (20 % on average), and North America (18 % on
average) . For 16.45 % of visitors, we could not detect whether they
used an ad blocker. These visitors did not stay long enough on the
website to complete ad blocker detection. On average, users spent a
short time on the website. Pre-study Google Analytics data provided
by the partner website showed that 84.81 % of visitors spend less
than 10 seconds on the site, 5.21 % 11 to 60 seconds, and 5.83 % up to
3 minutes. Our dataset includes all users for whom the event logs
indicated a fully loaded site, regardless of how long they stayed
on the page, resulting in a high number of “no action” visitors. As
described in Section 4.3, the median time until an interaction with
any version of the notice was 4 to 8 seconds. About 11,800 users
stayed on the page for 10 seconds or more.
The link to our survey was clicked 804 times (168 in Experiment
1, 445 in Experiment 2, and 191 in Experiment 3). We received a
total of 110 responses (16 in Experiment 1, 60 in Experiment 2, and
34 in Experiment 3), which means that 0.37 % of the 29,712 visitors
who interacted with the notice or stayed on the site for longer
than 30 seconds participated in the survey.. To get an impression of
visitors’ expectations about the website’s data collection practices,
we asked Q2: What do you think – what data does [the website]
collect about you when you access the website? This question was
answered by all participants. Across all three studies, the data most
commonly expected to be collected were links clicked on the site
(78 %), IP address (65%), posts read on the site (61%), and the device
used (59 %). Less often mentioned were other sites visited (29 %)
and the visitor’s place of residence (25 %). 13 % thought the website
collected their name, even though the site never asks for it. Only 5 %
thought the site did not collect any data about them. These answers
4
We count as “desktop computer” actual desktop machines as well as laptops. “Mobile”
devices include smartphones and tablets; the latter were used by 5.1 % of visitors.
95.1%4.5%
0.4%
97.8%1.8%
0.4%
65.7%18.4%
13.8%
96.4%3.4%2.3%
75.4%16.0%8.6%
95.7%
2.4%1.9%
0
25%
50%
75%
100%
86.8%8.9%4.3%
88.3%8.5%3.2%
70.9%34.4%7.9%
54.6%26.4%7.6%
96.5%2.9%
0.7%
85.6%11.9%
2.5%
No ActionAccept
Decline
Figure 3: Interaction rates in Experiment 1 (notice position),
arranged pairwise for mobile and desktop users.
indicate that the survey participants had a good understanding of
what data websites can collect even without user accounts.
4.2 Experiment 1: Banner Position
4.2.1 Interaction rates. Figure 3 shows how visitors interacted
with the consent notices displayed at dierent positions. Overall
the notices shown at the bottom-left position received the most
interactions, 33.1 % of visitors interacted with them regardless of
device type or choice made. The notice positions most commonly
observed in practice, small bars at the top or bottom, resulted in
low interaction (2.9 % and 9.6 %, respectively).
While we were mainly interested in position in Experiment 1,
we also analyzed the inuence of other variables, such as ad blocker
use, screen resolution, browser, operating system, and device type
(desktop/mobile). We estimated the eect size of dierent properties
by calculating Cramér’s V (CV) and over all visitors the banner posi-
tion showed the largest eect size (CV=.31). Unless noted otherwise,
χ2
-tests for eects in this experiment are statistically signicant
(p<.001).
Ad blocker use also had a small impact on whether someone in-
teracted with the notice. While on average 15.8 % of visitors without
an ad blocker interacted with any notice, only 12.6 % of ad blocker
users did so, but the eect size was rather small (CV=.11). The im-
pact of screen resolution was much higher on desktop (CV=0.33)
than on mobile (CV=0.16): Only 5.5% of visitors with screen resolu-
tions of 1,920 by 1,080 pixels or higher interacted with the notice,
while the average was 25.6 % for smaller screens. Although the de-
cline/accept ratio varied between conditions, we could not identify
a single factor to explain the dierences. Across all conditions the
number of users who accepted cookies was higher than the number
of those that declined.
4.2.2 Discussion. A possible explanation for higher interaction
rates with notices displayed at the bottom is that these notices are
more likely to cover the main content of the website, while notices
shown at the top mostly hide design elements like the website
header or logo. If one uses their thumb to navigate websites on a
smartphone, it is also easier to tap elements on the bottom part of
the screen than those at the top. An explanation for higher interac-
tion rates with notices displayed on the left of the viewport might
be the left-to-right directionality of Latin script: Line breaks cause
the information density of a text to be skewed to the left, so consent
notices positioned on the left are more likely to obstruct visitors’
reading and trigger an interaction with the notice. We looked for
qualitative feedback in the survey responses. In Experiment 1, we
received 16 responses, with eight participants having interacted
with the notice and another eight that did not. All six participants
who answered they had clicked the notice “because it prevented
them from reading the website content” had seen a notice shown
at the bottom or left side.
Both on desktop and mobile, the notice positioned in the bottom-
left corner received the most attention. Thus, we decided to display
the notices in Experiments 2 and 3 in the bottom-left corner.
4.3 Experiment 2: Choices & Nudging
In Experiment 2 there were 36,395 participants in total. Each of the
nine conditions was shown to 4,044 website visitors on average.
4.3.1 Interaction rates. Figure 4 provides an overview of the recorded
visitor interactions. Compared to Experiment 1, the overall percent-
age of visitors who interacted with the notice increased (13,8 %–
55,3 %), especially on mobile devices, likely because we had in-
creased the font size, resulting in larger notices. The highest in-
teraction rate (55 %) was measured for binary notices on mobile
devices.
The experiment revealed a strong impact of nudges and pre-
selections. Overall the eect size between nudging (as a binary
factor) and choice was CV=.50. For example, even for conrmation-
only notices, more users clicked “Accept” in the nudge condition,
in which it was highlighted (50.8 % mobile, 26.9 % desktop), than
in the non-nudging condition, in which “Accept” was displayed as
a text link (39.2 % m, 21.1 % d). The eect was most pronounced
for category- and vendor-based notices, in which all checkboxes
were pre-selected in the nudging conditions, but not in the privacy-
by-default conditions. The pre-selected versions led around 30 % of
mobile users and 10 % of desktop users to accept all third parties.
In contrast, only a small fraction (< 0.1 %) allowed all third parties
when given the opt-in choice and 1 to 4 % allowed one or more
third parties (“other” in Figure 4), indicating that some users still
engaged with the oered choices. No desktop visitors allowed all
categories. Interestingly, the number of non-interacting users was
highest on average for the vendor-based conditions, although they
took up the largest amount of screen space due to six options being
Figure 4: Visitors’ consent choices in Experiment 2. “Ac-
cept”/“Decline” indicate that (all) options were accepted
or declined. “Other” includes those who accepted/declined
only some options. Bold gures indicate default options.
oered. We discuss qualitative survey feedback on the category-
and vendor-based notices in Section 4.5.2.
4.3.2 Choices. Results were mixed in terms of the consent choices
users made when given options (in all but the no-option and conr-
mation conditions). Surprisingly, more participants accepted cook-
ies in both binary conditions, where they had the option to decline
cookies, than in the non-nudging conrmation condition, where
they could only accept cookies or not interact with the notice.
Figure 5 lists the specic choices participants made on category-
and vendor-based notices. Few visitors chose specic categories
or vendors if they were not pre-selected (non-nudging conditions).
Interestingly, more visitors selected specic vendors than categories.
Table 2: Comparison of interactions with category notices
Dataset Decision None pre-selected all pre-selected
Cookiebot (n = 1,135,090) (n = 1,988,681)
Accept 5.59 % 98.84 %
Decline 94.41 % 1.16 %
Our Data (n = 1,239) (n = 1,380)
Accept 0.16 % 83.55 %
Decline 99.84 % 16.45 %
Vendors YouTube and Ionic were selected most, even though survey
responses (Q6) indicated that Ionic was lesser known than other
listed vendors. We observe a similar pattern for the de-selection of
specic categories and vendors: More visitors unchecked one or
more vendors (10.0 %) than categories (6.9 %).
6 % of visitors who saw a category- or vendor-based notice
clicked at least one of the checkboxes more than once. 48 visi-
tors (0,08 %) toggled an even number of times, reversing previous
decisions. Interestingly, 47 of those users saw a “nudging” notice
so that they actively reactivated one of the categories.
We also recorded how long it took visitors to submit their choice.
The median time to submit for no-option, conrmation and binary-
choice notices was 4–5 seconds; 7–8 seconds for category- or vendor-
based notices.5For details see Appendix A.
4.3.3 External validation. To verify the generalizability of our re-
sults, which are only based on visitors to our partner website, we
compared our data to internal data from Cookiebot, a company
oering cookie consent notices (similar to our category-based con-
ditions) as a service to websites. Their dataset from February 2019
contains 3 million user logs for 2,000 dierent websites. The Cook-
iebot notices also show purpose categories, so we compare their
data with our data for the category-type notices. In their case, some
of the checkbox selections cannot be changed by users, as website
owners can argue that the use of certain cookie categories is based
on dierent legal grounds (e. g., “legitmate interest”, Art. 6 (1) (f)
GDPR). Therefore (de)selecting all consent-based cookie categories
in Cookiebot notices sometimes requires fewer clicks to be made,
and we were not able to compare decisions we labeled as “other”.
As shown in Table 2, Cookiebot has a slightly higher acceptance
rate (5.6 % compared to 0.16 % in our dataset) and a lower decline
rate when all boxes are pre-selected (1.2 % compared to 16.5 % in
our dataset). This means that our ndings are generally comparable,
but specic results may dier based on website and category, which
is what we would expect given that privacy preferences are highly
contextual [
3
]. A related 2017 study (n = 300) found that about
3 % of users are willing to accept marketing cookies [
34
], which
is between marketing acceptance in our non-nudging (0.6 %) and
nudging (7.3 %) conditions.
4.3.4 Discussion. Experiment 2’s results show that nudges and
pre-selection had a high impact on users’ consent decisions. It
5
We report the median as the data showed a high standard deviation since we had no
way to check when the interaction with a notice started, and sometimes the choice
was submitted minutes after the page had been loaded.
also underlines that the GDPR’s data protection by default require-
ment, if properly enforced, could ensure that consent notices collect
explicit consent. We further nd that most visitors make binary
decisions even when more choices are oered by agreeing to all or
no options. Only very few visitors selected specic categories or
vendors, while even in the non-nudging binary condition a consid-
erable number accepted the use of cookies. An explanation for this
behavior might be that those who are somewhat OK with cookie
use are not willing to expend eort on enabling it. Another expla-
nation, suggested by previous work [
27
], is that showing the actual
practices decreases the trust in a website and therefore leads to
more users making an informed decision to decline cookies.
4.4 Experiment 3: Language & Privacy Policy
Link
In Experiment 3, we tested four conditions with combinations of (a)
the notice including a link to the privacy policy (or not) and (b) the
text either referring to “cookies” or “your data” more generally. All
conditions were variants of the category-based, non-nudging notice
from Experiment 2. Figure 6 summarizes the results. All conditions
were shown to 6,032 visitors on average. Again, interaction rates
were higher for mobile visitors. As in Experiment 2, very few visi-
tors accepted all categories (0–0.1 %), but some visitors (0.3–1.4%)
explicitly allowed one or more. More people make a choice when
technical language is used, i. e., “cookie” is mentioned in the notice.
While this dierence is signicant (
χ2
-test, (
p<.
01), the eect size
is low (CV=.08), as are the dierences between conditions. Presence
of the privacy policy link had no signicant eect (p<.08).
4.4.1 Discussion. Experiment 3 showed that mentioning of cook-
ies has a minor inuence on users’ consent behavior. However,
dierences between conditions are small. This is not surprising
given that most users either submit the default choice or do not
interact with the notice at all. We could not conrm previous stud-
ies [
27
] that showed a negative eect on trust in a website when
a privacy policy was mentioned, but we found that more visitors
decline the use of cookies if a privacy policy is linked. Our ndings
indicate that position and choice have a more pronounced eect on
consent behavior than notice language or pointers to more privacy
information.
4.5 Survey Results
4.5.1 Reasons for (Non-)Interaction with Notices. In the survey (see
Appendix B), we asked participants why they did or did not click
on the consent notice. Participants could select multiple reasons.
44 of 61 survey participants who had clicked the notice reported
they had done so because they were annoyed by it. 16 thought the
website would not work otherwise, and 13 stated they had clicked
the notice out of habit. 11 participants interacted with the notice to
protect their privacy, 6 for security reasons, and 5 to see fewer ads.
49 participants had not interacted with the consent notice, 20 of
which reported they had not seen the notice. Nine thought clicking
the notice would not have any eect, six did not care what cookies
the website used or what data it collected, and three thought it did
not oer enough choices. Two reported to not know what cookies
were or what data the question was referring to. 13 participants se-
lected “other” and provided a free-text response. Recurring themes
Accepted Categories (default = none)
Rejected Categories (default = all)
Analytics
Marketing
Personalization
Privacy Policy
Submit
Analytics
Marketing
Personalization
Socialmedia
Submit
Absolute
0.6 %
Socialmedia
0.5 %
Privacy Policy
Accepted Vendors (default = none)
Rejected Vendors (default = all)
Facebook
Google Ads
Google Analytics
Google fonts
Ionic
Privacy Policy
Submit
Facebook
Google Ads
Google Analytics
Google fonts
Ionic
Privacy Policy
Submit
Youtube
1.3%
Youtube
Figure 5: Decisions to allow or decline specic categories (1) or vendors (2) in the the specic conditions of Experiment 2.
Subgraphs (a) show how many visitors checked specic boxes, subgraphs (b) how many unchecked pre-selected boxes.
% Visitors
No ActionAccept
Other
0%
25%
50%
75%
100%
66.8%0.1%1.2%31.9%
87.3%0.0%12.1% 0.6%
70.5%1.1%28.4%
88.80.5%10.6% 0.1%
0.0%
Decline
w/o PP-Link
& "Data"
w/ PP-Link
& "Data"
w/o PP-Link
& "Cookies"
62.7%0.1%1.4%35.8%
83.0%0.1%16.7% 0.3%
w/ PP-Link
& "Cookies"
63.4%0.1%1.1%33.4%
83.6%0.1%15.9% 0.4%
Figure 6: Visitors’ interactions with dierent consent mech-
anisms in Experiment 3. Notices contained technical lan-
guage (“cookies”) and a link to the privacy policy (or not).
in these responses include that the notices were “annoying [...], so
I just ignore them out of frustration” (Participant 2-94)
6
and that
participants thought no cookies would be set if they did not interact
with the notice. One participant mentioned that they “[found] all
of the partners suspicious” (2-255). One had opened the website in
a background browser tab, so they had only seen the invitation to
take the survey, and two participants reported that the notice had
been auto-replaced before they could click it.
4.5.2 Perception of Complex Consent Notices. We asked survey par-
ticipants who saw a category- or vendor-based notice to elaborate
on their choice selection (Q6), in order to learn how they perceived
purpose-based consent mechanisms as required by the GDPR. We
received 38 responses across Experiments 2 and 3. Appendix B
6
The rst digit in our participant identiers denotes the experiment and the second
the response ID assigned by LimeSurvey.
lists the codes and their distribution for this and the following
open-response questions.
A recurring theme in the responses was transparency, as men-
tioned by 5 participants who had seen a category-based notice: “[I
liked] that I could directly select the options without going to the
settings. It would be great if this was the default” (3-171), “What
I like [here] is that only [the ...] necessary option is selected and
all of the others are deactivated” (3-88). One participant with a
vendor-based notice stated: “Having options makes me feel secure”
(2-619).
However, participants had diverging opinions regarding the no-
tices’ clarity. Some found the categories “self-explanatory” (3-118).
Others pointed out that “Necessary [from a technical perspective]
does not say much. Cookies aren’t necessary to view a website”
(3-215) and that “something could be hidden” (2-557) behind the
Necessary category. 6 (of 7) participants who saw a vendor-based
notice in Experiment 2 reported it had “too much text, too many
options. I’m interested in the website’s content, not in the consent
notice” (2-116), and one suggested “it would be perfect to have a
button to (de)activate all cookies” (2-199). Seven participants based
their choices on privacy considerations: “I don’t tick anything. I only
need advice [from] the website” (3-108), “I don’t want personalized
web pages, ads, [... and] pointers to social media” (3-165).
These responses indicate that more complex notices are not
necessarily problematic, as long as options are not pre-selected.
While some express concerns, do not trust the categorizations, or
nd the choices too complex, others appreciate the privacy-by-
default approach.
4.5.3 Understanding of Consent Notice Behavior. The survey fur-
ther investigated participants’ general understanding of how con-
sent notices work and what it meant to accept or decline cookies.
This section was identical in all three studies. The participant was
shown the binary notice depicted in Figure 1 (a) (bb). Then we
asked the following two free-text questions: Q7: What do you think
happens when you click “Decline”? Q8: What do you think happens
when you click “Accept”?
4.5.4 Declining Cookies. For Q7 (Decline), we received 94 responses
across the three studies. We identied ten themes. The most promi-
nent expectation was that declining cookies would prevent access
to the website (28 responses): “I don’t get access to the desired in-
formation” (1-282), “The site closes itself and you are redirected to
the search engine” (2-685). 17 other participants expected parts of
the website not to work: “I won’t be able to use some functionality
because [...] cookies fund the website” (2-255). Only 4 participants
explicitly mentioned that they would be able to access the site,
stating, for example, “Normally I can continue to navigate the site.
It has only happened twice that [a] site has kicked me out. But on-
line shopping [is] dicult if you don’t agree” (2-94). 3 participants
expected no collection or processing of personal data to take place
when cookies are declined but still had doubts “I hope that no data
is collected” (1-177, 1-121, 3-216). 12 expected the site to behave
as if “Accept” were clicked: “I guess my data is still collected” (1-
170), “Nothing, of course. Me not accepting cookies does not mean
that the site uses less or no cookies or does not collect any data
about me” (2-630). Other recurring themes in the responses include
the expectation to see less ads, a focus on the technical aspects
(“no cookies are evaluated” [3-217]), and if the notice would dis- or
reappear. See Appendix B for details.
For Q8 (Accept), which was also answered by 94 participants (not
all the same respondents as for Q7), we also identied 10 themes. 29
participants expected their personal data would be collected and/or
processed: “my behavior on the website is stored and analyzed”
(2-216), “my data is shared with who knows what third parties
[...] Facebook, Google, marketing / market research / ad analytics
[...]” (2-557). 19 responses focused on technical aspects: “a cookie
is set which recognizes me when I revisit the website” (1-250). 21
participants stated the website would only work if they allowed
cookies: “I can read the article” (2-53), “I can continue to use the
website” (2-405). Other themes included eects on the consent
notice only (“the banner disappears” [2-675]), personal data being
collected for advertising, user proling, and other purposes, e. g.,
“sale to third parties” (3-171), “inuencing Internet algorithms” (1-
269), and “any purpose” (1-207, 3-64). 7 participants believed it
made no dierence what was clicked but did not specify what that
“default” behavior of the website would be.
These answers indicate that our participants had some under-
standing of how cookies are used, e. g., to recognize recurring vis-
itors and for ad tracking and targeting. Concerningly, almost a
quarter of participants thought they had to accept cookies before
they could access a website – negative experiences on some sites
may be inuencing general expectations and behavior across web-
sites. A transparent and GDPR-compliant consent notice should
inform users which website functionality may not work as intended
if cookies are declined.
5 RELATED WORK
Multiple measurement studies of varying scope have provided in-
sights about the prevalence of consent notices [
5
,
12
,
49
]. Even
though many consent notice libraries can be congured to only
display a notice to EU visitors [
12
], van Eijk et al. [
49
] found that
a website’s top-level domain was the primary factor in whether a
consent notice was displayed rather than a visitor’s location.
Sanchez-Rola et al. [
38
] evaluated the functionality of consent no-
tices and opt-out mechanisms under GDPR. They manually visited
2,000 popular websites, tried to opt out of data collection whenever
possible, and studied the eects on the website’s cookies. They
found that 92 % of websites set at least one high-entropy cookie
before showing any kind of notice. Only 4 % of notices provided an
opt-out choice, and 2.5 % of websites removed some cookies upon
opt-out. Degeling et al. [
12
] further found that many third-party
consent libraries either lack the functionality to block or delete
cookies, or require signicant modication of a website to properly
react to visitors’ consent choices.
In Section 2, we presented a detailed analysis of variants in con-
sent notices’ graphical user interfaces. Previous work had only
classied consent notices by the provided information [
22
], the
choices oered [
12
,
38
], and if the notice blocks access to the web-
site [
38
]. Van Eijk et al. [
49
] report some statistics on the height and
width of consent notices, their location oset, and notices’ word
and link/button counts.
Kulyk et al. [
22
] investigated users’ perceptions of and reactions
to dierently worded cookie consent notices. They identied ve
categories of disclaimers based on the amount of information pro-
vided about the purposes of cookie use and the parties involved. In
a qualitative user study, they found that the text of a cookie notice
does not signicantly inuence users’ decisions to continue using
a website; their decision was rather based on the website’s per-
ceived trustworthiness and relevance. The participants perceived
cookie consent notices as a nuisance or threat to their privacy, and
reported lacking information about the implications of cookies and
possible countermeasures.
Users’ perceptions of consent notices’ choice architectures have
only been partially studied before. Boerman et al. [
7
], using Dutch
panel data, explored how users protect their online privacy. Given
the opportunity to decline cookies, many participants self-reported
that they decline cookies “often” (16 %) or “very often” (17 %). Facing
the decision to either accept cookies or leave the website, 12 % and
13 % reported to refrain from using the site “often” and “very often,”
respectively.
Previous work has shown that cookies are poorly understood
by Web users. Ha et al. [
19
] studied the usability of two cookie
management tools in focus groups, identifying misconceptions
about cookies and risks associated with them. Kulyk et al. [
23
]
developed and tested a privacy-friendly cookie settings interface
for the Chrome browser and found that users appreciate tools that
help them better understand the standard browser cookie settings,
such as an assistant that transforms users’ privacy preferences into
cookie settings or additional explanations about the purpose and
security/privacy implications of dierent types of cookies.
Consent notices are not the only way for Web users to opt out
of targeted advertising. Previous work has evaluated the usability
of dierent opt-out tools [
18
,
20
,
24
] and found that users nd it
dicult to locate, congure, and understand these mechanisms.
Schaub et al. describe the design space for privacy notices and
controls, including consent notices and permission prompts on
mobile devices [39].
Warning research and ad placement studies provide insights
into the eects of user interface design choices on user attention
and behavior; examples include color [
40
] and position [
9
]. Studies
investigating dierent notice designs were conducted, for example,
for SSL [16], browser security [33], and phishing warnings [13].
Mathur et al. [
28
] classied common dark patterns in web ser-
vices. In their classication scheme the observed actions are de-
scribed as “sneaking” (attempting to misrepresent user actions, or
delay information that, if made available to users, they would likely
object to), “misdirection” (using visuals, language, or emotion to
steer users toward or away from making a particular choice), and
“forced action” (forcing the user to do something additional in order
to complete their task).
6 DISCUSSION
We conducted three experiments evaluating the eects of cookie
consent notices’ position, choices, and content on people’s consent
behavior. In the following we describe recommendations based on
our ndings and discuss limitations of our approach.
6.1 Recommendations
Our experiments investigated dierent notice positions, details of
the choices oered, and the wording of cookie consent notices.
Future guidelines for consent notices should consider the following
recommendations:
Position. Experiment 1 showed that the position of a notice has
a substantial impact on whether a website visitor engages with
the notice. A dialog box in the lower left corner (on desktop) or
the lower part of the screen (on mobile) signicantly increases the
chance that a user makes a consent decision. While we had expected
higher interaction rates on mobile devices for this position since it
is easy to reach with the thumb, we were surprised by the impact
on desktop users, given the general wisdom that content in the
top left receives the most attention in cultures with left-to-right
writing. This result could be related to our partner website, like
many websites, displaying a header which shifted content to lower
parts of the screen. This experiment shows that the second most
common notice position observed in practice, the top position (see
Table 1), results in notices being ignored by users.
Choices. Our results from Experiment 2 showed that nudging
(highlighting “Accept” buttons or pre-selecting checkboxes) sub-
stantially aects people’s acceptance of cookies, providing clear
evidence for the interference of such dark patterns with people’s
consent decisions. Given a binary choice, more visitors accepted
cookies than declined them, which could be evidence for the ad-
verse eects of consent bundling on consent decisions, which is
not allowed under the GDPR. Surprisingly, rejection rates in the
vendor- and cookie-based conditions were close to those in the bi-
nary condition, although visitors had to make ve to six additional
clicks to reach the same goal. This suggests that people who want
to decline cookies are willing to expend extra eort.
Moreover, the survey answers show that participants think that
no data is collected unless they make a decision, showing that
privacy by default is the expected functionality, although this is
not the current practice.
Text. While we did not see an eect in Experiment 3 from includ-
ing a privacy policy link in the notice, we found that mentioning
“cookies” made more users reject the data collection. The nega-
tive eect of mentioning cookies can very well be related to the
fact that Internet users have in general a negative feeling about
them [19, 22].
It is clear that the current ecosystem of mechanisms to prompt
for user consent — with a plethora of combinations regarding the
provided information, the granularity of user options, and how
and if their choice is enforced — — provides no real improvement
for user privacy compared to pre-GDPR times. At the same time
many things are still in ux, with regulators publishing diering
guidelines on how to obtain consent, the online advertising industry
developing and updating proposals for consent frameworks, and
legal and technical scholars evaluating them. While some claim [
36
]
that many underlying principles of the online advertising industry
are not compatible with the GDPR at all, the regulation so far has
only partially aected how companies process personal data [
48
].
We hope that our results can inform future discussions, not only
with recommendations for the design of consent notices. Given
that at the moment very few users are willing to give consent to
any form of processing of their personal data, we think that the
business model of online behavioral advertising, which targets ads
based on large amounts of personal data, should be challenged and
alternative models like privacy-friendly contextual advertising or
other ways of monetization for web services need to be developed.
6.2 Limitations
Our study has some potential limitations. First, our sample is bi-
ased as we conducted all experiments on a German-language e-
commerce website whose visitors may not be representative of the
general public. However, our partnership with this website gave us
control over the notice implementation and access to a high number
of unique visitors. We validated some of our results with data from
Cookiebot which showed similar results (see Section 4.3.3). Overall
it seems our sample is more inclined towards rejecting cookies.
We have to assume that in general a higher percentage of users
may allow cookies. Our eld study did not allow us to collect more
detailed information about visitors, such as their specic device,
the size of the notice on the screen, or how long they stayed on the
website, which could potentially have an eect on consent behavior.
Furthermore, many visitors did not interact with the notice at all
and spent only a short period of time on the site. While this could be
related to the notice, it is not unusual that most visitors leave a site
after a few seconds. Liu et al. [
25
] showed that website dwell time
has a negative aging eect. Users rst skim a site to decide whether
they will stay on it. Since we were not able to measure the exact
time visitors stayed on the site, we included all users for whom the
logged data indicated a fully loaded page, which results in a high
number of “no action” visitors. From a legal perspective the time
spent on the site does not aect the need to request consent. Our
partner website also does not have user accounts. Past research has
shown that visitors tend to underestimate the amount of personal
data collected by websites on which they do not create an account
and enter personal data [
32
]. This may cause them to underestimate
the privacy implications of allowing cookie use, but we did not see
evidence for this in the survey responses.
Responses to our voluntary survey are likely biased due to par-
ticipants’ self-selection. Responses to the question about possible
data collection suggest that participants had a good understanding
of the technical background or an interest in privacy. Of the survey
participants, 61 had previously interacted with our consent notices
and 49 had not, showing that the results are only partially biased
towards those who care about notices. We considered this bias
when interpreting results.
7 CONCLUSION
We conducted the rst large-scale eld study on the eect of cookie
consent notices on people’s consent behavior. Cookie notices have
seen widespread adoption since the EU’s General Data Protection
Regulation went into eect in May 2018. Our ndings show that
a substantial amount of users are willing to engage with consent
notices, especially those who want to opt out or do not want to
opt in to cookie use. At the same time, position, oered choices,
nudging, and wording substantially aect people’s consent behavior.
Unfortunately, many current cookie notice implementations do not
make use of the available design space, oering no meaningful
choice to consumers. Our results further indicate that the GDPR’s
principles of data protection by default and purposed-based consent
would require websites to use consent notices that would actually
lead to less than 0.1 % of users actively consenting to the use of
third-party cookies.
ACKNOWLEDGMENTS
The authors would like to thank the owner of their partner website
for allowing them to display dierent sets of consent notices on
this site. Additional thanks to Yana Koval for her help with the
implementation of the WordPress plugin and the classication of
existing consent notices. This research was partially funded by the
MKW-NRW Research Training Groups SecHuman and NERD.NRW,
the German Research Foundation (DFG) within the framework of
the Excellence Strategy of the Federal Government and the States
(EXC 2092 CaSa – 39078197), and the National Science Foundation
under grant agreement CNS-1330596.
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https://doi.org/10.1007/s12599-016- 0453-1
A TIMING IN EXPERIMENT 2
Table 3: Average time in seconds until users submitted deci-
sion in Experiment 2, if decision was made within the rst
three minutes
Banner Type # Users Mean Median SD
No Option 4174 6.51 4 15.55
Conrmation non-nudging 2984 10.65 5 51.25
nudging 3634 9.11 4 37.78
Binary non-nudging 4134 15.36 4 72.47
nudging 4097 13.51 4 75.59
Category non-nudging 2523 17.93 8 87.16
nudging 2798 13.98 7 64.01
Vendor non-nudging 2346 13.76 8 42.38
nudging 2741 21.18 7 115.26
B SURVEY AND RESPONSES
Rindicates answers displayed in random order. All questions and answers were translated from German as true to the original as possible.
Motivation for Interacting With the Cookie Consent Notice
Q1-clickeda: You just clicked the cookie consent noticebon the website [WEBSITE_NAME]. Which of the following statements describe your
motivation to click the notice? I clicked the cookie consent notice ... [multiple choice]
Exp. 1 Exp. 2 Exp. 3 Total %
... to protect me from dangers from the Internet.R0 3 3 6 9.8 %
... to protect my privacy on the Internet.R0 5 6 11 18.0 %
... because the website does not work otherwise.R2 11 3 16 26.2 %
... to see less ads.R1 1 3 5 8.2%
... out of habit.R1 10 2 13 21.3 %
... because the notice distracts me from viewing the website.R6 25 13 44 72.1 %
Other: [free text] 0 0 1 1 1.6%
I do not know why I clicked the notice. 1 1 1 3 4.9%
I prefer not to answer. 0 0 0 0 0 %
# Answers 11 56 32 99 162.3 %
# Participants 8 34 19 61 100.0 %
Q1-notclicked:aYou did not click the cookie consent noticebon the website [WEBSITE_NAME]. Which of the following statements describe your
motivation to not click the notice? I did not click the cookie consent notice ... [multiple choice]
Exp. 1 Exp. 2 Exp. 3 Total %
... because I have not noticed it.R4 11 5 20 40.8 %
... because it did not oer enough choices.R0 0 3 3 6.1%
... because I do not know what happens if I click the notice.R1 6 4 11 22.4 %
... because I think that my selection does not have any eect.R1 4 4 9 18.4 %
... because I do not know what cookies are.R0 2 0 2 4.1%
... because I do not care which cookies the website uses.Rc 1 3 2 6 12.2 %
... Other: [free text] 1 10 2 13 26.5 %
... I do not know why I did not click the cookie consent notice. 1 0 0 1 2.0 %
... I prefer not to answer. 0 2 0 2 4.1%
# Answers 9 38 20 67 136.7 %
# Participants 8 26 15 49 100.0 %
aQ1-clicked and Q1-notclicked were only displayed to participants who clicked / did not click the notice, respectively.
b
In Experiment 3, “cookie consent notice” was changed to “privacy notice” in the conditions Non-Technical–PP Link and Non-Technical–No PP Link.
c
In Experiment 3, this answer was changed to “because I do not know what data this is about” in the conditions Non-Technical–PP Link and
Non-Technical–No PP Link.
Expectation of the Website’s Data Collection
Q2: What do you think – what data does the website [WEBSITE_NAME] collect about you when you access the website?
Exp. 1 Exp. 2 Exp. 3 Total %
The posts I am reading on the website.R10 40 17 67 60.9 %
My residence.R6 14 7 27 24.5 %
The links I click on the website.R14 45 27 86 78.2 %
My IP address.R11 39 22 72 65.5 %
The device I am using to access the website.R10 36 19 65 59.1 %
The website does not collect any data about its visitors.R0 4 1 5 4.5 %
My name.R2 9 3 14 12.7 %
Other websites I visit besides [WEBSITE_NAME].R5 17 10 32 29.1 %
Other: [free text] 3 2 1 6 5.5 %
I prefer not to answer. 0 0 0 0 0 %
# Answers 61 206 107 374 340.0 %
# Participants 16 60 34 110 100.0 %
Perception of the Cookie Consent Notice Displayed to the Participant
This is the cookie consent noticeathe website has shown you. [IMAGE]
Please rate the following statements about this notice.
Q3: I think the number of choices oered by the above cookie consent noticebis ...
Exp. 1 Exp. 2 Exp. 3
BIN-S1c
NOP
CON-NN
CON-NU
BIN-NN
BIN-NU
CAT-NN
CAT-NU
VEN-NN
VEN-NU
TE-PP
TE-NP
NT-PP
NT-NP
... too low 9 3 3 5 3 1 1 2 1 2 1 1 0 1
... just right 7 1 0 3 7 3 2 3 1 2 4 8 6 6
... too high 0 0 1 1 0 0 3 2 0 3 2 0 3 0
... No answer 0 2 0 1 2 0 1 0 1 0 0 0 2 0
Total 16 6 4 10 12 4 7 7 3 7 7 9 11 7
Q4: The above cookie consent noticeaallows me to control the website’s behavior.
Exp. 1 Exp. 2 Exp. 3
BIN-S1
NOP
CON-NN
CON-NU
BIN-NN
BIN-NU
CAT-NN
CAT-NU
VEN-NN
VEN-NU
TE-PP
TE-NP
NT-PP
NT-NP
Strongly disagree 6 3 3 0 2 0 1 1 0 1 1 1 0 0
Somewhat disagree 3 2 0 3 3 2 2 1 1 3 2 0 3 0
Neutral 6 0 1 4 3 0 0 1 1 1 1 1 4 2
Somewhat agree 1 1 0 2 4 1 4 3 1 1 1 4 4 5
Strongly agree 0 0 0 0 0 1 0 1 0 1 2 2 0 0
No answer 0 0 0 1 0 0 0 0 0 0 0 1 0 0
Total 16 6 4 10 12 4 7 7 3 7 7 9 11 7
Q5b: I think the decision which option to select in the cookie consent noticea
is ...
Exp. 2 Exp. 3
CAT-NN
CAT-NU
VEN-NN
VEN-NU
TE-PP
TE-NP
NT-PP
NT-NP
... very easy 2 0 1 1 4 3 4 1
... easy 0 2 1 0 0 2 2 2
... neither easy nor hard 2 2 0 2 2 2 5 4
... hard 2 2 1 2 1 1 0 0
... very hard 1 1 0 2 0 0 0 0
No answer 0 0 0 0 0 1 0 0
Total 7 7 3 7 7 9 11 7
a
In Experiment 3, “cookie consent notice” was changed to “privacy notice” in the conditions
Non-Technical–PP Link and Non-Technical–No PP Link.
b
Q5 was only shown to participants who had seen a category- oder vendor-based notice on the
website.
c
BIN-S1 = the binary notice shown at six dierent positions in Experiment 1; NOP = no option;
CON = conrmation; BIN = binary; CAT = categories; VEN = vendors; NN = non-nudging; NU =
nudging; TE = technical; NT = non-technical; PP = privacy policy link; NP = no privacy policy
link.
Perception of the Cookie Consent Notice Displayed to the Participant (cont.)
Q6a
: Please explain your answer to the previous question. [free text answers, coded by two authors]
Code Explanation Exp. 2 Exp. 3 Total %
Transparent The participant considers the consent notice to be transparent. 1 5 6 15.8%
Privacy The participant’s preferences are privacy-focused, i. e., the least invasive option is chosen. 2 5 7 18.4 %
Options clear The options oered by the consent notice are considered clear / easy to understand. 0 3 3 7.9 %
Options unclear The options oered by the consent notice are considered unclear / not easy to understand. 4 2 6 15.8%
Notice clear The participant expressed that the mechanism was clear but did not specify which part. 1 3 4 10.5%
Notice unclear The participant expressed that the mechanism was unclear but did not specify which part. 2 0 2 5.3 %
Too complicated The consent notice was considered too complex. 4 1 5 13.2 %
Don’t care The participant stated they did not care which cookies the website used. 3 0 3 7.9 %
Other 4 2 6 15.8 %
# Participants 60 34 110 100.0 %
aQ6 was only shown to participants who had seen a category- oder vendor-based notice on the website.
General Understanding of Cookie Consent Notices
This is another cookie consent notice. [Image of the binary notice in Figure 1 (a) (bb)]
Q7: What do you think happens when you click “Decline”? [free text answers, coded by two authors]
Code Explanation Exp. 1 Exp. 2 Exp. 3 Total %
Site blocked The content of the website cannot be accessed at all. 6 13 9 28 29.8 %
Functionality limited The content of the website can be viewed, but some parts may not work. 2 10 5 17 18.1 %
Site accessible The content of the website can be accessed. 0 3 1 4 4.3%
No data collected The website visitor’s personal data is not collected or processed. 2 4 5 11 11.7 %
No cookies set The website does not store any cookies in the visitor’s browser. 1 8 3 12 12.8 %
Less ads The website displays less or no ads. 0 3 2 5 5.3 %
Notice The participants only mentions eects regarding the consent notice. 0 2 3 5 5.3 %
No change Declining cookies does not have any eect. 4 7 1 12 12.8 %
Don’t know 2 0 1 3 3.2 %
Other 0 2 4 6 6.4 %
# Participants 15 51 28 94 100.0 %
Q8: What do you think happens when you click “Accept”? [free text answers, coded by two authors]
Code Explanation Exp. 1 Exp. 2 Exp. 3 Total %
Data collected The participant’s personal data is collected and/or processed. 9 10 10 29 30.9 %
Cookies stored Cookies are stored in the user’s browser. 4 9 6 19 20.1%
Site accessible The content of the website can be accessed. 0 16 5 21 22.3%
Notice The participants only mentions eects regarding the consent notice. 0 3 2 5 5.3 %
Ads The participant is subject to advertising. 6 11 6 23 24.5%
Proling The participant’s personal data is used to create a prole of their interests. 5 8 6 19 20.2 %
Other purposes The participant’s personal data is used for other purposes. 2 0 2 4 4.3 %
No change Clicking “Accept” does not have any eect. 0 4 3 7 7.4 %
Don’t know 0 3 0 3 3.2 %
Other 0 3 1 4 4.3 %
# Participants 15 51 28 94 100.0 %
... The users' reliance on peripheral cues and cognitive shortcuts can be deliberately exploited by so-called dark design patterns to increase their acceptance to disclose personal data (Soe et al. 2020;Waldman 2020). For instance, participants in a study by Utz et al. (2019) accepted to have their data treated by third parties if acceptance was the pre-selected option on the notice; the same option was selected more often when coloured in blue instead of grey. Chang et al. (2016) found that the participants were more likely to disclose sensitive information about themselves (e.g. about their sexual experiences) if they were exposed to provocative profile pictures on a fictitious social network than participants who were exposed to less provocative images. ...
... The context of security and privacy notices has been considered in terms of the conspicuity of the notice against their perceptual background, for instance by varying their position, interativity and colour (e.g. Utz et al. 2019). The context is also taken into account in studies varying the temporal relation between the appearance of the privacy notice and the activity at stake: active warnings (i.e. ...
... Earlier work also consistently found that opt-out mechanisms were hard for users to understand and use [11], [12], [14], [17], [19], [24]- [26]. However, those studies were conducted prior to the adoption of CCPA and focused on the usability of opt-out mechanisms under earlier laws, such as the CAN-SPAM Act and GDPR. ...
Preprint
The California Consumer Protection Act (CCPA) gives users the right to opt-out of sale of their personal information, but prior work has found that opt-out mechanisms provided under this law result in very low opt-out rates. Privacy signals offer a solution for users who are aware of their rights and are willing to proactively take steps to enable privacy-enhancing tools, but this work findsthat many users are not aware of their rights under CCPA and that current opt-out rates are very low. We therefore explore an alternative approach to enhancing privacy under CCPA: increasing the visibility of opt-out of sale mechanisms. For this purpose, we design and implement CCPA Opt-out Assistant (COA), a browser extension that automatically detects when websites sell personal information and presents users with a visible, standardized banner that links to the opt-out of sale mechanism for the website. We conduct an online user study with 54 participants that finds that these banners significantly increases the rate at which users opt-out of sale of their personal information. Participants also report less difficulty opting-out and more satisfaction with opt-out mechanisms compared to the native mechanisms currently provided by websites. Our results suggest that effective privacy regulation depends on imposing clear, enforceable visibility standards, and that CCPA's requirements for opt-out of sale mechanisms fall short.
... Analyzing cookie policies on websites, also an important research topic, ten fines (1%) are assigned for not providing users the option to refuse their cookies (ETid-86 ), for insufficient information about the purpose, properties, and activation time (ETid-364 ), or for cookie banners missing completely (ETid-220 ). This is in line with previous works that identified that cookie banners do not work as intended [23], are misleading, or unusable in general [9,32]. ...
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... Lately research like Elbert et al. [13] indicates how well designed consent notices can improve understanding of privacy practices by highlighting important features. H-4: Enforce Good Practices Utz et al. did the first study showing that design patterns can be used to increase consent rates [40], a practice now known as "consent optimization". Service providers and consent managers make use of "dark patterns" to manipulate users into consenting [35]. ...
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Data Protection and Consenting Communication Mechanisms (DPCCMs) have the potential of becoming one of the most funda�mental means of protecting humans’ privacy and agency. However, they are yet to be improved, adopted and enforced. In this paper, based on the results of a technical document analysis and an expert study, we we identify some of the main technical factors that can be com�parison factors betwe some of the main interdisciplinary challenges of a Human-centric, Accountable, Lawful, and Ethical practice of personal data pro�cessing on the Internet and discuss whether the current DPCCMs proposal can contribute towards their resolution. In particular, we discuss the two current open specifications, i.e. the Advanced Data Protection Control (ADPC) and the Global Privacy Control (GPC) based on the identified challenges.
... With the help of features such as customization and drill-down visualisations, the CURE UI achieves higher transparency concerning personal data processing. To avoid the all-or-nothing approach, which is used by existing consent requests (see Nouwens et al. 2020;Utz et al. 2019), the CURE UI allows users to decide between maximum privacy with minimum device utility by using a slider bar (the bottom of the slider indicated minimum privacy). Further, the CURE UI allows consent revocation by sliding the pointer up in order to withdraw multiple purposes at once or manually (i.e., one can deselect individual purpose by deselecting the corresponding checkbox). ...
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... Concerning the platform-consumer relationship, literature on DPR mainly discusses the role of platform governance (Perrons 2009) and behavioral economics. i.e., user's contradictory attitudes and behavior towards data privacy (Reyna 2018), or their willingness to pay for free-to-use platform services (Sunstein 2020), and how this affects competition and regulation in digital markets (Luguri and Strahilevitz 2019;Utz et al. 2019). ...
Thesis
Digital transformation (DT) has not only been a major challenge in recent years, it is also supposed to continue to enormously impact our society and economy in the forthcoming decade. On the one hand, digital technologies have emerged, diffusing and determining our private and professional lives. On the other hand, digital platforms have leveraged the potentials of digital technologies to provide new business models. These dynamics have a massive effect on individuals, companies, and entire ecosystems. Digital technologies and platforms have changed the way persons consume or interact with each other. Moreover, they offer companies new opportunities to conduct their business in terms of value creation (e.g., business processes), value proposition (e.g., business models), or customer interaction (e.g., communication channels), i.e., the three dimensions of DT. However, they also can become a threat for a company's competitiveness or even survival. Eventually, the emergence, diffusion, and employment of digital technologies and platforms bear the potential to transform entire markets and ecosystems. Against this background, IS research has explored and theorized the phenomena in the context of DT in the past decade, but not to its full extent. This is not surprising, given the complexity and pervasiveness of DT, which still requires far more research to further understand DT with its interdependencies in its entirety and in greater detail, particularly through the IS perspective at the confluence of technology, economy, and society. Consequently, the IS research discipline has determined and emphasized several relevant research gaps for exploring and understanding DT, including empirical data, theories as well as knowledge of the dynamic and transformative capabilities of digital technologies and platforms for both organizations and entire industries. Hence, this thesis aims to address these research gaps on the IS research agenda and consists of two streams. The first stream of this thesis includes four papers that investigate the impact of digital technologies on organizations. In particular, these papers study the effects of new technologies on firms (paper II.1) and their innovative capabilities (II.2), the nature and characteristics of data-driven business models (II.3), and current developments in research and practice regarding on-demand healthcare (II.4). Consequently, the papers provide novel insights on the dynamic capabilities of digital technologies along the three dimensions of DT. Furthermore, they offer companies some opportunities to systematically explore, employ, and evaluate digital technologies to modify or redesign their organizations or business models. The second stream comprises three papers that explore and theorize the impact of digital platforms on traditional companies, markets, and the economy and society at large. At this, paper III.1 examines the implications for the business of traditional insurance companies through the emergence and diffusion of multi-sided platforms, particularly in terms of value creation, value proposition, and customer interaction. Paper III.2 approaches the platform impact more holistically and investigates how the ongoing digital transformation and "platformization" in healthcare lastingly transform value creation in the healthcare market. Paper III.3 moves on from the level of single businesses or markets to the regulatory problems that result from the platform economy for economy and society, and proposes appropriate regulatory approaches for addressing these problems. Hence, these papers bring new insights on the table about the transformative capabilities of digital platforms for incumbent companies in particular and entire ecosystems in general. Altogether, this thesis contributes to the understanding of the impact of DT on organizations and markets through the conduction of multiple-case study analyses that are systematically reflected with the current state of the art in research. On this empirical basis, the thesis also provides conceptual models, taxonomies, and frameworks that help describing, explaining, or predicting the impact of digital technologies and digital platforms on companies, markets and the economy or society at large from an interdisciplinary viewpoint.
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