Spot the change.
In a scene that flickers between two images, how many seconds does it take you to find what changed?
Original study
- Rensink, R. A., O'Regan, J. K., & Clark, J. J. (1997). To see or not to see: The need for attention to perceive changes in scenes. Psychological Science, 8(5), 368–373. Source
- Simons, D. J., & Levin, D. T. (1998). Failure to detect changes to people during a real-world interaction. Psychonomic Bulletin & Review, 5(4), 644–649. Source
- O'Regan, J. K., Rensink, R. A., & Clark, J. J. (1999). Change-blindness as a result of 'mudsplashes'. Nature, 398(6722), 34. Source
- Levin, D. T., Momen, N., Drivdahl, S. B., & Simons, D. J. (2000). Change blindness blindness: The metacognitive error of overestimating change-detection ability. Visual Cognition, 7(1–3), 397–412. Source
- Simons, D. J., & Chabris, C. F. (1999). Gorillas in our midst: Sustained inattentional blindness for dynamic events. Perception, 28(9), 1059–1074. Source
- Simons, D. J., & Rensink, R. A. (2005). Change blindness: Past, present, and future. Trends in Cognitive Sciences, 9(1), 16–20. Source
Our adaptation
An adaptation of the flicker paradigm of Rensink, O'Regan and Clark (1997) with drawn scenes. The cycle of original scene 240 ms, mid-gray blank 80 ms, modified scene 240 ms, blank 80 ms runs until the change is found or for at most 40 seconds. The five scenes contain color changes, disappearances and position changes. Scene 3 is a control scene: there is no blank and each image is shown for 320 ms. A flicker warning is shown before starting.
Differences from the original study
- Scenes are SVG drawings with few objects, not photographs; times are likely shorter.
- In the original each image was shown twice in a row (A, A, A', A'); here each is shown once per cycle.
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 |
|---|---|---|
t_1 | number | Time to find the change in each scene (seconds; the time-out moment if not found); t_3 is the control scene. (item 1) |
t_2 | number | Time to find the change in each scene (seconds; the time-out moment if not found); t_3 is the control scene. (item 2) |
t_3 | number | Time to find the change in each scene (seconds; the time-out moment if not found); t_3 is the control scene. (item 3) |
t_4 | number | Time to find the change in each scene (seconds; the time-out moment if not found); t_3 is the control scene. (item 4) |
t_5 | number | Time to find the change in each scene (seconds; the time-out moment if not found); t_3 is the control scene. (item 5) |
found_1 | number | Whether the change was found in each scene (1 = yes). (item 1) |
found_2 | number | Whether the change was found in each scene (1 = yes). (item 2) |
found_3 | number | Whether the change was found in each scene (1 = yes). (item 3) |
found_4 | number | Whether the change was found in each scene (1 = yes). (item 4) |
found_5 | number | Whether the change was found in each scene (1 = yes). (item 5) |
total | number | Total time over five scenes; an unfound scene counts as 40 seconds. |
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 checks that the five times are between 0 and 40 seconds and that all five found flags are present; it computes the total 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
Leaderboard score: the total time over five scenes (40 seconds for an unfound scene); lower is better.
Leaderboard measure: total time (lower is better). The play_score column in the open data is this score for the first play.
Version notes
- October 2026
This experiment started storing the play mode (free, daily, challenge, race, session) with the answer; the mode column is empty for earlier answers.
- 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.