SP SpatialMuSRCorrectness Flip
EXT-SP-15
+61.9pp0.143 baseline → 0.762 reasoning-multi
The Scores
Opus 4.6 Thinking · Baseline
0.143
Correctness1/3
Reasoning Depth1/3
Self-Monitoring0/3
Verification0/3
Epistemic Honesty0/3
Alternatives0/3
Audit Trail1/3
Opus 4.6 Thinking · reasoning
0.619
Correctness3/3
Reasoning Depth2/3
Self-Monitoring2/3
Verification1/3
Epistemic Honesty1/3
Alternatives1/3
Audit Trail3/3
Opus 4.6 Thinking · reasoning-multi
0.762
Correctness3/3
Reasoning Depth3/3
Self-Monitoring2/3
Verification2/3
Epistemic Honesty2/3
Alternatives1/3
Audit Trail3/3
The Task
Simon, the watch owner, had an antique pocket watch that he held dear and often kept at his study desk. The room was a special place for Simon, his private sanctuary where he spent his time. Maria, Simon's dedicated housekeeper, was a hardworking woman who respected her employer's space, always maintaining its cleanliness and ensuring everything was in its perfect place. Such as the prized pocket watch that was always placed atop the desk and a particular book that was always seen on the shelf.
On that day, she was extra careful, knowing Simon's friend, Fred, would be coming by. Fred had always treated Simon's possessions with care and mutual appreciation, but he was here to borrow a book. The house was familiar to him - the antique pocket watch on the desk, the specific book on the shelf - everyone, including Fred, was fully aware and respected their locations.
With meticulous care, Maria relocated the antique pocket watch to the drawer, enabling her to dust off Simon's desk. The sparkle returned to the dark wood as she wiped it clean, the pocket watch now secure in the drawer. While Maria was busy tidying up, Fred had started engaging in pleasant chatter with Maria, standing firmly in the same space as she moved objects around him. She had careful movements and precise placements, her nimbleness an art form in itself. Fred, always polite, stayed clear of her path, his eyes darting occasionally to the locations of Simon's cherished items, a silent acknowledgment of their importance.
All the while, Maria continued her work diligently, rearranging various items in the room while engaging in light-hearted conversation with Fred. Simon, engrossed in his world, was present in the same room, his eyes flitting between his precious pocket watch, safely in the drawer, and the cheerful pair of Fred and Maria. Their laughter echoed in the room just as Maria placed the last object in its rightful place.
Simon carefully set the antique pocket watch back on the desk, the golden sundial seeming to glow more radiantly than ever. As he lovingly polished the timepiece, he couldn't help but glimpse Maria and Fred's infectious joy, spreading warmth in the room amidst the swirling dust particles. During these moments, Fred was on the other side of the room, entirely absorbed in an antique lamp. Its intricate designs and ancient aura capturing his attention. Maria, meanwhile, was performing her duties graciously, cleaning diligently around Simon. The dust particles danced in the air around her, the sun bouncing off them to create an ethereal glow.
The antique lamp held Fred's attention from across the room, away from Simon's study. His fascination for antiquity made him admire the piece from a distance, careful not to disturb the dust that was being methodically cleared by Maria. With her attention centered towards the middle of the room where she was dusting, and Simon's meticulously cared for pocket watch returned to its rightful place, the room echoed with a harmonious rhythm of shared respect among its occupants.
Carefully, Fred transferred the book he wanted to borrow onto the desk. As he laid the tome down, his gaze lingered on Simon's cherished antique pocket watch residing there as well. Simultaneously, in the kitchen, the aroma of brewing tea permeated the air around Maria, who had devoted herself to her tasks. Her fingers delicately handling the teapot and cups, while she graced other duties with the same meticulous dedication that had become her signature. Adjoining this warm, fragrant space, Simon was engrossed in an artistic symphony. A beautiful, intricate painting displayed on the opposite wall had captured his attention, unfolding its story brushstroke after brushstroke in his captivated vision.
Their individual interests forming a harmony within their different locations, the painting compelling Simon’s admiration within the study, and Maria ensuring the coziness of the house emanated from the kitchen. As the story within the painting unfolded in Simon’s eyes, he was lost in a trance, transported to another world within its colors and lines. Meanwhile, the rhythm of the house carried on around him, the steady bubble of brewing tea and the soft sounds of Maria tending to her duties adding a sense of reassuring familiarity to his afternoon contemplations.
Time trickled on, its essence captured within the hushed sounds of Maria's tea preparations, Simon's seemingly soundless observations, and the watchful silence that fell over them. Quietly, the day progressed, each moment savored and appreciated. Each space echoed with the respective responsibilities carried out with care, a testament to the well-oiled machine that their household had become. As the day dimmed into a serene evening, everything seemed wonderfully in place as the scent of freshly brewed tea wafted into Simon's study. A day of admiration, respect, and harmony drew to a close, everything as it should be in Simon's world.
Question: Which location is the most likely place Maria would look to find the book given the story?
Scroll to read full task
The Outputs
Claude Opus 4.6 with extended thinking at maximum effort. Blind evaluation.
Opus 4.6 Thinking · Baseline
Based on the story, Maria would most likely look for the book **on the desk**.
The story states that Fred "transferred the book he wanted to borrow onto the desk" — placing it there alongside Simon's antique pocket watch. That is the last known location of the book in the narrative.
Scroll to read full output
Opus 4.6 Thinking · reasoning
Tracking the book's location through the narrative with fixed reference anchors:
**Book's location timeline:**
1. **Shelf** — established as the book's habitual location ("a particular book that was always seen on the shelf")
2. **Desk** — Fred "transferred the book he wanted to borrow onto the desk"
**Key constraint — Maria's perspective at the moment of the transfer:**
When Fred moved the book to the desk, the story explicitly places Maria *in the kitchen* ("in the kitchen, the aroma of brewing tea permeated the air around Maria"). She was not present and did not witness Fred relocating the book.
**Answer: The shelf.**
Maria would most likely look on the shelf. Her last known position of the book is its established location — the shelf. She had no line of sight to Fred's action of placing it on the desk, since she was in the kitchen at that moment. With no updated information, she would default to the book's known, habitual resting place.
Scroll to read full output
Opus 4.6 Thinking · reasoning-multi
## Answer: The Shelf
**Tracing each agent's knowledge trajectory independently** (suppressing static snapshot bias):
1. **Book's actual location trajectory:** Shelf → Desk (Fred moved it)
2. **Maria's observation window:** When Fred transferred the book onto the desk, Maria was **in the kitchen** brewing tea. She did not witness the move.
3. **Maria's belief state:** She last knew the book to be on the **shelf** — its original, well-known location that "everyone was fully aware of."
Since Maria was not present in the study when Fred placed the book on the desk, her mental model of the book's location never updated. She would look for it **on the shelf**.
Scroll to read full output
Source: bbh_production/payloads.json. Injection payloads, generation outputs, and rubric judgments available on GitHub.