Who would you save?.
A self-driving car with failed brakes has to hit one of two groups. The choice is yours: which group do you save, and should such choices be written into software as rules?
Original study
- Awad, E., Dsouza, S., Kim, R., Schulz, J., Henrich, J., Shariff, A., Bonnefon, J.-F., & Rahwan, I. (2018). The Moral Machine experiment. Nature, 563(7729), 59–64. Source
- Bigman, Y. E., & Gray, K. (2020). Life and death decisions of autonomous vehicles. Nature, 579(7797), E1–E2. Source
- Awad, E., Dsouza, S., Kim, R., Schulz, J., Henrich, J., Shariff, A., Bonnefon, J.-F., & Rahwan, I. (2020). Reply to: Life and death decisions of autonomous vehicles. Nature, 579(7797), E3–E5. Source
- Bonnefon, J.-F., Shariff, A., & Rahwan, I. (2016). The social dilemma of autonomous vehicles. Science, 352(6293), 1573–1576. Source
- Ethics Commission on Automated and Connected Driving. (2017). Report (June 2017). Federal Ministry of Transport and Digital Infrastructure, Germany. Source
- Foot, P. (1967). The problem of abortion and the doctrine of the double effect. Oxford Review, 5, 5–15.
- Thomson, J. J. (1985). The trolley problem. The Yale Law Journal, 94(6), 1395–1415. Source
Our adaptation
A short adaptation of the Moral Machine experiment of Awad et al. (2018). In twelve dilemmas a car with failed brakes either goes straight or swerves; either way one group is spared and the other is not. The dilemmas test five dimensions one at a time (humans–animals, more–fewer, young–old, lawful–crossing on red, passengers–pedestrians); in two dilemmas the groups are identical. The car's lane and card order are random; a single policy question comes at the end.
Differences from the original study
- Choice is forced; Bigman and Gray (2020) showed that many people pick 'treat both equally' when it is offered.
- Gender, status and body size of the characters are not shown.
- There are far fewer scenarios than in the original.
Measured variables
The columns of the open data file. List fields are expanded into numbered columns (for example rt_60, est_3); JSON columns contain only numbers and fixed stimulus names.
| Column | Type | Description |
|---|---|---|
s | JSON | Dilemmas: [[dilemma no, side spared 0 a / 1 b, swerved 1/0, time ms] × 12]. |
pref_species | number | Preference per dimension (−1…1; +1 = sparing the reference side): species (humans), lives (more), age (younger), law (lawful), relation (pedestrians); inaction: tendency to go straight (−1…1). (species) |
pref_lives | number | Preference per dimension (−1…1; +1 = sparing the reference side): species (humans), lives (more), age (younger), law (lawful), relation (pedestrians); inaction: tendency to go straight (−1…1). (lives) |
pref_age | number | Preference per dimension (−1…1; +1 = sparing the reference side): species (humans), lives (more), age (younger), law (lawful), relation (pedestrians); inaction: tendency to go straight (−1…1). (age) |
pref_law | number | Preference per dimension (−1…1; +1 = sparing the reference side): species (humans), lives (more), age (younger), law (lawful), relation (pedestrians); inaction: tendency to go straight (−1…1). (law) |
pref_relation | number | Preference per dimension (−1…1; +1 = sparing the reference side): species (humans), lives (more), age (younger), law (lawful), relation (pedestrians); inaction: tendency to go straight (−1…1). (relation) |
pref_inaction | number | Preference per dimension (−1…1; +1 = sparing the reference side): species (humans), lives (more), age (younger), law (lawful), relation (pedestrians); inaction: tendency to go straight (−1…1). (inaction) |
policy | integer | Policy question: 0 should not discriminate, 1 should prioritize the young, 2 not sure. |
Columns present in every file (14)
row_id | string | Row code. Regenerated at random in every release; it does not identify a person and cannot be matched across releases or experiments. |
experiment | string | Short name of the experiment (URL slug). |
experiment_version | integer | Version of the answer format. For experiments whose format changed, only the current format is published. |
date | YYYY-MM-DD | YYYY-Www | YYYY-MM | Day the answer was given (Istanbul time). If fewer than 5 answers share the same day, language and device, it is coarsened to the ISO week, and to the month if that is still too few. |
date_precision | day | week | month | Precision of the date column. |
lang | tr | en | (boş) | Interface language. Language recording started in the first week of October 2026; for earlier answers it is known only in experiments whose stimuli depend on the language, and empty otherwise. |
device | desktop | mobile | tablet | (boş) | Device class reported by the browser (class only; browser details are neither stored here nor published). |
source | site | embed | Where the answer came from: the balabs site or the experiment embedded on another site. The embedding site is not published. |
mode | free | daily | challenge | race | session | (boş) | Play mode in scored experiments: free play, daily round, challenge, race room, experiment session. Empty for unscored experiments and for older answers that did not store it. |
color_vision | normal | rg | by | contrast | (boş) | In color-based experiments, the color vision mode the participant chose: normal, red-green, blue-yellow or high contrast. Stimuli are generated along different axes per mode, so compare within a mode. Empty for other experiments. |
first_play | 1 | Every row is a participant’s first play of this experiment (always 1). Replays are stored only as leaderboard scores and are not part of the open data. |
seen_before | yes | no | unsure | (boş) | Participant’s own report of whether they had seen this experiment or its known answer before (in experiments that ask). |
duration_s | number | Time from the start of the experiment to submitting the answer, in seconds (measured in the browser, 0.1 s). |
play_score | number | Leaderboard score of the first play (scored experiments; defined on the method card). Empty for unscored experiments. |
Exclusion criteria
The server requires an answer to each of the twelve dilemmas and the policy question, and computes the preference scores itself.
- Only each participant's first answer to this experiment; replays are not included.
- Simulated rows, bots, banned and sample accounts are not included.
- Answers before 3 October 2026 are not included (the first day the open data notice was live).
Scoring
This experiment has no leaderboard score. The crowd result is the mean preference per dimension and the distribution of the policy answer.
Version notes
- October 2026
The interface language (lang) started being stored with each answer; for earlier answers it is known only in experiments whose stimuli depend on the language, and empty otherwise.