Awareness-related activity in prefrontal and parietal cortices reflects more than superior performance capacity: A blindsight case study
Bibliographic record
Abstract
Background: Brain imaging studies on visual awareness have often reported activity in prefrontal and parietal cortices. One interpretation could be that such activity reflects the capacity to perform visual tasks, which is usually high when one is aware of the stimulus, and at near-chance-level when one is unaware. The opportunity to study a blindsight patient allowed us to test this interpretation, by creating performance-matched conditions with dramatic differences in subjectively reported levels of awareness. Patient GY has a damaged primary visual cortex in the left hemisphere (“blind”), with the right side being relatively intact (“normal). It is well-documented that he can perform forced-choice tasks better than chance in his “blind” visual field. Methods: We presented gratings of strong contrast to his “blind” field, and weak contrast to his “normal” field, such that performance in a spatial 2AFC task was matched between the two. We assessed the level of awareness by standard subjective report (“Seeing” vs “Guessing”), confidence rating, and post-decision wagering. All of these measures supported the conclusion that the level of awareness differed dramatically, even though performance capacity was matched between the “blind” field and “normal” field stimulations. Results: 1. Comparing “normal” field vs. “blind” field stimulations, we found robust activations in the prefrontal and parietal cortices. 2. Whereas accuracy in the “normal” field (correct vs. incorrect trials) was driven by activity in the occipital and temporal cortices (sometimes bilaterally), accuracy in the “blind” field was driven mainly by subcortical activity, with a clear lack of activation in the occipital cortex. Conclusions: 1. Activity in prefrontal and parietal cortices is likely to reflect the ability to monitor and report perceptual certainty appropriately, rather than just superior visual performance capacity. 2. Blindsight is supported by subcortical mechanisms, as previously suggested.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".