Assignment 2: Conditions and data: a randomized interference pilot
Weight: 10 course points. Due: Before Meeting 3. Expected work: 3 hours.
Task
Extend the Meeting 2 Stroop starter to 16 trials: eight congruent and eight incongruent. Each ink color must occur twice in each condition. Give every item a unique ID, randomize the order without changing these counts, and store word, ink, condition, expected response, response, omission, and correctness. If a color task is unsuitable, use left/right central arrows with congruent/incongruent flankers and balanced target directions; document the substitution.
Show total trials, omissions, accuracy over all task trials, and mean RT for correct finite responses, overall and by condition. N/A must appear when an eligible subset is empty. Download CSV and JSON.
Required checks
Hand-calculate accuracy and mean correct RT for a four-row subset, then compare with your code. Run an all-timeout pilot to show that no NaN/Infinity or 0 ms mean is fabricated. Run twice and report the observed order; different order is plausible but not guaranteed by randomization. Counts must remain balanced regardless of order.
Submit
Follow the common submission requirements. Include the runnable experiment, a synthetic/self-pilot export, and a short note with your checks. Keep a failed run when it demonstrates an intended branch; label it clearly. Do not collect research participants for this assignment.
Rubric
| Criterion | Evidence | Points |
|---|---|---|
| Design and item balance | 16 items; eight per condition; target colors/directions balanced within condition | 2 |
| Reusable procedure | Correct v8 timeline variables, fixation, randomized order | 2 |
| Scoring and labels | Correct mappings, omission handling, independent answer-key check | 2 |
| Summaries | Explicit denominators, correct finite RT filter, empty-subset guard | 2 |
| Pilot and explanation | Exports, two observed orders, hand-calculated subset, attribution | 2 |
| Total | 10 |
Optional extension (no extra points required for full credit)
Describe a possible congruency contrast without treating this pilot as evidence for an effect. Explain why full randomization does not guarantee alternation and why equal condition counts do not remove item confounds.
Submit through the course website. This local copy is for reading and preparation.