A simultaneous depth and rivalry paradigm imaged with fMRI
Bibliographic record
Abstract
Psychophysical experiments have shown that it is possible to simultaneously perceive binocular depth and rivalry in plaids. Depth may be perceived from the near-vertical components, while the diagonal components undergo rivalry, as long as the components are in different spatial frequency or orientation bands (Buckthought & Wilson, 2007). Here we used fMRI at 3T to image activity in visual cortex while human subjects perceived depth and rivalry simultaneously from plaids. This was compared to the activation obtained with near-vertical or diagonal gratings in which depth or rivalry alone was perceived. In conditions with depth, an interocular orientation disparity (5 degrees) was used to produce tilt, and this cue alternated every three seconds between top tilted forward or backward. Hence, the perceived depth alternated dynamically, analogous to the rivalry percept. Six subjects performed either a rivalry or depth task with the plaid or grating stimuli by indicating when alternations occurred. In three experimental conditions the spatial frequencies of the near-vertical and diagonal components were, respectively: (a) 2.5, 6.4 cpd; (b) 6.4, 2.5 cpd; (c) 6.4, 6.4 cpd. We found that the network of activated cortical areas was remarkably similar for the rivalry and depth task. When subjects viewed plaids, some areas were activated more during the depth task than the rivalry task independent of spatial frequency (e.g. posterior superior temporal sulcus), while in other regions the bias was for the higher (e.g., calcarine cortex) or lower spatial frequency component (e.g., MT+). Placing depth and rivalry components in different spatial frequency bands allowed us to find greater differences between the two. Activation when depth and rivalry were perceived in isolation (gratings) was higher than when depth and rivalry were perceived simultaneously (plaids), consistent with inhibitory interactions between the mechanisms for depth and rivalry. We conclude that depth and rivalry are subserved by similar mechanisms, and are perceived simultaneously by coexisting in different spatial frequency or orientation channels. Binocular vision models must be revised to incorporate these findings.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".