Phase 4: Shot-event expansion and epoching

[neuromechanist]

Goal

Expand stimulus-side shot events into each subject's event structure and epoch around shot onsets.

Entrypoint

src/matlab/phase4_epoch.m.

Steps

• expand_events using repo-root shot_events.tsv; drop rows with has_boy=n/a and has_puppy=n/a
• Epoch -0.6 to 0.6 s around the new shots events
• Tag epochs with has_boy, has_puppy, LLR, shot_number
• Apply Contrast 1 split: boy-only (has_boy=1 & has_puppy=0) vs puppy-only (has_boy=0 & has_puppy=1)
• Drop epochs whose baseline window would overlap a prior shot onset
• Emit qa_trials.csv: subject, n_boy_only, n_puppy_only, n_dropped_overlap
• Drop subjects below minimum-per-condition floor (tentative >=10 trials); empirically revisit
• Save epoched sets to derivatives/epochs/

Success Criteria

• Per-subject trial counts in each condition documented
• Inclusion floor chosen based on empirical distribution, recorded in .context/research.md

Parent

Part of epic #1. Blocked by Phase 3.