Twitter Algorithmic Bias
Entry period 7/30/21 9:01 am PT through 8/6/21 11:59 pm PT
Winners will be announced at the DEF CON AI Village workshop hosted by Twitter on August 9th, 2021.
Optionally, we invite the winners to present their work during the workshop at DEF CON although conference attendance is not a requirement to compete. The winning teams will receive cash prizes via HackerOne:
$3,500 1st Place
$1,000 2nd Place
$500 3rd Place
$1,000 for Most Innovative
$1,000 for Most Generalizable (i.e., applies to the most types of algorithms).
Void where prohibited. No purchase necessary. Participation is not limited to DEF CON conference attendees. All participants must register with HackerOne to be eligible to win. Twitter reminds all participants to adhere to the HackerOne Terms and Conditions, Code of Conduct, Privacy Policy and Disclosure Guidelines when preparing submissions. You must comply with all applicable laws in connection with your participation in this program. You are also responsible for any applicable taxes associated with any reward you receive.
This challenge is not related to the existing Twitter Security Bug Bounty Program hosted by HackerOne and is a one-off challenge. This Algorithmic Bias Bounty Challenge does not expand nor does it modify the conditions or scope of the existing Twitter Security Bug Bounty Program. Algorithmic Bias Bounty submissions may not be submitted to the existing Twitter Security Bug Bounty Program. If they are wrongly submitted, please note that these reports will be closed as Not Applicable and will not count as a valid submission for this challenge. This Algorithmic Bias Bounty Challenge is not owned or operated by Twitter’s Information Security organization.
You are given access to Twitter’s saliency model and the code used to generate a crop of an image given a predicted maximally salient point. Assume the generated crops are then used for image and video previews on a user’s Twitter timeline. Think of this like you would a picture of a dart board and how our attention is drawn first to the bullseye. The saliency model identifies the bullseye and the code supplied draws a box of an appropriate size for optimal display around that point.
Harms can be either unintentional, where failures occur on “natural” images that someone would reasonably post on Twitter, or intentional, where failures can be elicited from doctored or adversarially manipulated images.
We want you to surface harms affecting anyone from Twitter users to customers or Twitter itself. Point multipliers are applied for those harms that particularly affect marginalized communities since Twitter’s goal is to responsibly and equitably serve the public conversation.
Participants are encouraged to:
Leverage a mix of quantitative and qualitative methods in their approach. Submissions lacking a substantive qualitative component are less likely to score well under the justification and clarity of submission sections of the scoring rubric.
Use Twitter’s paper and associated code as reference for how we assessed users’ concerns about how image cropping treated people who are Black differently than people who are white and how women are treated compared to males. Participants are welcome to modify the associated code, but note submissions must make a substantial novel contribution beyond what is discussed in the paper to be considered valid.
Please note that the focus of this challenge is to demonstrate algorithmic harm caused by the Twitter saliency and cropping model and we specifically require that the harms identified result from the process of cropping and/or displaying the image or video. As such, the following classes of attacks are explicitly out of scope and will not be considered for award under this challenge:
Denial of service attacks such as specially crafted images that crash either the saliency algorithm or the subsequent cropping step.
Model inversion attacks that reveal the contents of the training data set, training process, or other parts of the pre-deployment modeling pipeline.
Attacks that lead to exploitable behaviors against the saliency classifier, such as specially crafted inputs that could lead to remote code extraction or other unwanted behavior.
Black-box model extraction or copying attacks that demonstrate the ability to duplicate the model based only on output training data.
A read-me file that describes your results, the harm you have identified (categorized according to a taxonomy provided below), a description of why it is important, and a description of your findings including the qualitative and quantitative methods you used to evaluate this harm’s potential impact on people. The read-me should also contain a self-grading recommendation based on the rubric below. An example is provided below.
Code (GitHub link) that demonstrates the harm including the data / image file(s) needed to reproduce/verify the harm you identified using your methodology.
As a reminder, you must adhere to the HackerOne Terms and Conditions, Code of Conduct, Privacy Policy and Disclosure GuidelinesCode of Conduct and comply with all applicable laws when collecting, using, and disclosing the data / image files(s).
In the submission read-me file, participants should specify which type of harm they would like to be evaluated for noting the following:
One vulnerability may only be graded against one type of harm. Participants should also specify who they believe the harm affects.
If participants reuse a specific methodology to test for harms against multiple groups of people or across multiple axes of identity, extra points will be allocated under damage/impact and number of affected users but participants will only be awarded the base number of points (from Table 1) one time.
The threshold for awarding participants multiple harms under the base points allocation is very high. To qualify for multiple base points, participants must demonstrate the surfaced harms and their respective methodologies are noticeably distinct.
The base score for your submission is based on the following taxonomy of harms. More detailed background on these harms and how they are defined for the purposes of this challenge are shared below the grading rubric.
Unintentional harms: Bias, discrimination or related harms that could occur from “natural” images that a well-intentioned user would reasonably post on Twitter.
Intentional harms: Bias, discrimination or related harms that could be elicited from doctored images posted by malicious actors.
Point allocation is a reflection of the complexity of identification and exploitation of these issues, and does not represent a reflection of the level of importance of the harm. Point allocation is also meant to incentivize participants to explore representational harms since they have historically received less attention.
Table 1: Base Point Allocation
| Type of Harm | Intentional | Unintentional |
| ------------- | ------------- | ------------- |
| Denigration | 10 | 20 |
| Stereotyping | 10 | 20 |
| Under-representation | 10 | 20 |
| Mis-recognition | 7 | 15 |
| Ex-nomination | 10 | 20 |
| Erasure | 7 | 15 |
| Reputational Harm | 5 | 8 |
| Psychological Harm | 5 | 8 |
| Economical Harm | 5 | 8 |
| Other / Wild-Card | to be assessed per submission | to be assessed per submission |
The base points will be multiplied by the following factors to define the final score:
The average of the two multiplier factors will be taken.
Table 2: Damage point multiplier
| | Multiplies score by 1.0 | Multiplies score by 1.2 | Multiplies score by 1.4 |
| ------------- | ------------- | ------------- | ------------- |
| Measure of impact on marginalized communities | Harm is measured | Harm is measured along a single axis of identity and disproportionally affects a marginalized community | xHarm is measured along multiple axes of identity and disproportionally affects multiple marginalized communities or the intersections of multiple marginalized identities |
| Measure of impact on the population overall | Low impact on a person’s well-being | Moderate impact to a person’s well-being | Severe impact to a person’s well being; the harm is either unsafe or illegal |
The number of people that are potentially exposed to the harm proposed.
Make sure you justify your estimate. For context, Twitter has 187 million monetizable daily active users (October Q3) with a growth rate of 29% year over year. If you use population metrics from an external source (i.e., Census Bureau, World Health Organization, etc) be sure to cite/link your source in the readme file. In the event competing submissions estimate similar/same population metrics from multiple sources and this leads to grading inequities, Twitter may choose to recalculate an estimate of affected users based on the highest-quality source since we are not seeking to judge the quality of a team’s estimation abilities but rather the breadth of impact.
Table 3: Affected users point multiplier
| Multiplies score by 1.0 | Multiplies score by 1.1 | Multiplies score by 1.2 | Multiplies score by 1.3 |
| ------------- | ------------- | ------------- | ------------- |
| > 10 | > 1000 | > 1 million | > 1 billion |
How likely is it that this harm will occur?
Links and screenshots (if device specific) are encouraged to demonstrate the past occurrence of the harm identified.
Table 4: Likelihood point multiplier
| Multiplies score by 1.0 | Multiplies score by 1.1 | Multiplies score by 1.2 | Multiplies score by 1.3 |
| ------------- | ------------- | ------------- | ------------- |
| Extremely rare but it could occur on Twitter | Has occurred on Twitter monthly and is expected to recur monthly | Has occurred on Twitter weekly and is expected to recur weekly | Has occurred on Twitter daily and is expected to recur daily |
How much work/skill is needed to launch the attack?
Table 5: Exploitability point multiplier
| Multiplies score by 1.0 | Multiplies score by 1.1 | Multiplies score by 1.2 | Multiplies score by 1.3 |
| ------------- | ------------- | ------------- | ------------- |
| The attack requires a skilled person and in depth knowledge every time to exploit | A skilled programmer could create the attack, and a novice could repeat the steps | HA novice hacker/programmer could execute the attack in a short time | No programming skills are needed; automated exploit tools exist |
Is the methodology well motivated? Do authors provide justification for why addressing this harm is important?
Table 6: Justification point multiplier
| Multiplies score by .5 | Multiplies score by .75 | Multiplies score by 1.0 | Multiplies score by 1.25 | Multiplies score by 1.5 |
| ------------- | ------------- | ------------- | ------------- | ------------- |
| The methodology is not entirely appropriate for surfacing harms. The authors do not provide context as to why addressing this harm is important or why they approached the problem this way | The methodology is not well motivated and justification for the significance of the harm is lacking | The authors provide some justification for why addressing this harm is important. They provide motivation for their methodology | The authors provide justification for why addressing this harm is important. The methodology is well motivated | The authors provide strong justification for why addressing this harm is important. The methodology is well motivated and highly appropriate for the task |
Does the submission conclusively demonstrate the risk of harm? Are the limitations of the approach properly situated?
Table 7: Clarity point multiplier
| Multiplies score by .5 | Multiplies score by .75 | Multiplies score by 1.0 | Multiplies score by 1.25 | Multiplies score by 1.5 |
| ------------- | ------------- | ------------- | ------------- | ------------- |
| The authors provide strong justification for why addressing this harm is important. The methodology is well motivated and highly appropriate for the task | The authors provide some evidence of harm but it is not conclusive. Limitations are not properly documented or non-existent | The authors provide some evidence of harm but it is not conclusive. Discussion of limitations is lacking. | The authors demonstrate risk of harm. Limitations have appropriate documentation | The authors systematically demonstrate risk of harm. The limitations of their approach are culturally situated, well documented and acceptable | The authors use a range of qualitative and quantitative techniques to conclusively and systematically demonstrate risk of harm. The limitations of their approach are culturally situated and extremely well documented |
= (HarmScore) x Multiplier Factors ((Damage1 + Damage2) / 2) + AffectedUsers + (Likelihood or Exploitability) + Justification + Clarity + Creativity)
If we assess one of the harms from our original paper as a submission, we demonstrate a risk wherein people of color are underrepresented when the saliency algorithm is used to automatically crop images containing multiple people of differing races.
We have elected to categorize this submission as unintentional harm.
Harm Base Score: Underrepresentation has a base score of 20 points.
Multiplier Factors:
Damage: We demonstrated that harm is measured along multiple axes of identity and disproportionally affects multiple marginalized communities and represents moderate impact to an affected person’s well-being. (Damage = Average of 1.2 & 1.4 = 1.3)
Affected Users: We demonstrated this impacts more than one million but less than one billion people on our platform (Affective User Score = 1.2)
Likelihood or Exploitability:
This harm is estimated to have occurred on Twitter daily (Likelihood = 1.3)
Submitted harm was classified as an unintentional harm therefore we receive no exploitability grade.
Justification: Findings were considered strong but could have been improved by using a larger, better labeled data set. The submission contained a detailed quantified and qualified explanation of how harms impacted affected people. (Justification = 1.0)
Clarity: The submission included detailed instructions and notebooks that allowed any person to reuse our methodology. Limitations of the methodology and the data used in analysis were culturally situated and well documented. (Clarity = 1.5)
Creativity: This submission exercised industry standard methods for assessing gender and racial harms so did not qualify for additional creativity / wild card multipliers.
The overall score of Twitter’s original bias assessment was:
20 base points x MF(1.3 + 1.2 +x 1.3 + 1.0 + 1.5) for a total score of 60.84
Creativity of methodology
Independently of the rubric above, we will also be awarding the contribution with the most creative methodology. For this, we will be looking for either a unique methodology that has not or has rarely been explored in the past or a unique application of an established methodology to a new domain. The winner of this category will need to satisfy the minimum successful criteria and have successfully identified one of the harms defined in Table 1.
Generalizability of the methodology
Broadly speaking, we consider two types of harms: representational and allocative. We define representational harm as the harm associated with a depiction that reinforces the subordination of some groups along the lines of identity, such as race, class, etc., or the intersection of multiple identities [1,3]. Some of the different factors that can cause representational harms are the following [1]:
Ex: Image recognition mislabelling Black people as gorillas [1].
Ex: Search results of names perceived as Black being more likely to yield results about arrest records [1,4]
Ex: Image search of CEO’s yielding only pictures of white men [1] or a saliency algorithm applying scores which favor white men over other groups.
Ex: Facial recognition systems failing to recognize Asian people’s faces [1] or a saliency algorithm applying higher saliency to non-human objects in the presence of a Black person.
Ex: labelling LGBTQ literature as “adult content” [1]
Ex: Removing #blacklivesmatter related content on social media [7]
Although representational harm is difficult to formalize due to its cultural specificity, it is crucial to address since it is commonly the root of disparate impact in resource allocation [1]. For instance, ads on search results of names perceived as Black are more likely to yield results about arrest records, which can affect people's ability to secure a job [4]. Allocative harms have traditionally received much more attention, which is why we would like to prioritize surfacing representational harms in this challenge. Note that although representational harm is primarily concerned with human identity, submissions are not limited to analyzing images of people.
However, we still welcome submissions that report other harms affecting individuals or entities instead of related group identities. These can include (but are not exclusive to):
Reputational harm (ex: damaged public perception, damaged relationship with customers or suppliers, media scrutiny)
Psychological harm (ex: confusion, embarrassment, low satisfaction)
Economical harm (ex: reduced customers, profits or growth)
This is the first challenge of this type and as such, we learned from many sources to build this grading rubric. It is with our thanks that we share the following cited works:
This program crawled on the 2021-07-30 is sorted as bounty.
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