Track the balls.
Ten identical balls are bouncing around. How many of them can you keep track of at once without losing them?
Original study
- Pylyshyn, Z. W., & Storm, R. W. (1988). Tracking multiple independent targets: Evidence for a parallel tracking mechanism. Spatial Vision, 3(3), 179–197. Source
- Scholl, B. J. (2009). What have we learned about attention from multiple-object tracking (and vice versa)? In D. Dedrick & L. Trick (Eds.), Computation, cognition, and Pylyshyn (pp. 49–78). MIT Press. Source
- Alvarez, G. A., & Franconeri, S. L. (2007). How many objects can you track? Evidence for a resource-limited attentive tracking mechanism. Journal of Vision, 7(13), 14. Source
- Franconeri, S. L., Jonathan, S. V., & Scimeca, J. M. (2010). Tracking multiple objects is limited only by object spacing, not by speed, time, or capacity. Psychological Science, 21(7), 920–925. Source
- Hulleman, J. (2005). The mathematics of multiple object tracking: From proportions correct to number of objects tracked. Vision Research, 45(17), 2298–2309. Source
- Meyerhoff, H. S., Papenmeier, F., & Huff, M. (2017). Studying visual attention using the multiple object tracking paradigm: A tutorial review. Attention, Perception, & Psychophysics, 79(5), 1255–1274. Source
- Fehd, H. M., & Seiffert, A. E. (2008). Eye movements during multiple object tracking: Where do participants look? Cognition, 108(1), 201–209. Source
Our adaptation
An adaptation of Pylyshyn and Storm's (1988) multiple object tracking (MOT) task. Each round has ten identical balls in a square field; K targets flash orange for 2 seconds, then all balls move for 6.5–7.5 seconds and, when they stop, K balls are marked. The number of targets follows a staircase starting at 2 (all correct +1, one missed same, more missed −1; range 2–6). Speed rises every round (from 0.20 to 0.32 field widths per second). Motion is computed from the game seed.
Differences from the original study
- Speeds are given relative to the field width, not in degrees per second; screen size is unknown.
- The chance correction assumes that only targets are tracked.
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 |
|---|---|---|
r | JSON | Rounds: [[K targets, number of balls, correctly marked, speed (field/s × 1000), motion time ms, answer time ms, frame rate fps] × 5]. |
m_1 | number | Number of targets tracked in the round after chance correction (Hulleman, 2005). (item 1) |
m_2 | number | Number of targets tracked in the round after chance correction (Hulleman, 2005). (item 2) |
m_3 | number | Number of targets tracked in the round after chance correction (Hulleman, 2005). (item 3) |
m_4 | number | Number of targets tracked in the round after chance correction (Hulleman, 2005). (item 4) |
m_5 | number | Number of targets tracked in the round after chance correction (Hulleman, 2005). (item 5) |
pts_1 | number | Round score: 2.5 × m. (item 1) |
pts_2 | number | Round score: 2.5 × m. (item 2) |
pts_3 | number | Round score: 2.5 × m. (item 3) |
pts_4 | number | Round score: 2.5 × m. (item 4) |
pts_5 | number | Round score: 2.5 × m. (item 5) |
points | number | Total score (at most 50). |
cap | number | Highest m (capacity estimate). |
full | integer | Largest K with all targets found. |
kmax | integer | Largest K reached. |
fps | number | Mean frame rate. |
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 number of targets matches the staircase derived from earlier rounds and that the speed follows the plan; inconsistent submissions are rejected.
- 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: total score (at most 50); higher is better.
Leaderboard measure: ball tracking (higher is better). The play_score column in the open data is this score for the first play.
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.