Line bisection in simulated homonymous hemianopia
Bibliographic record
Abstract
Homonymous hemianopia is a frequent visual field defect after injury of the postchiasmatic visual pathway. It has long been known that hemianopic patients make systematic errors during line bisection, placing bisection markers not in the centre of the line but biased instead toward their visual field defect. The cause for this contralesional bisection error is unknown. Various hypotheses attribute the error to the visual field defect, long-term strategic adaptation to the defect, or, more recently suggested, a consequence of extrastriate brain injury. To determine if bisection error can occur without the contribution of the latter two factors, we studied line bisection in healthy subjects with simulated homonymous hemianopia using a gaze-contingent display paradigm, with different line lengths and the presence or absence of line-end markers. We found that simulated homonymous hemianopia induced a line bisection error towards the simulated hemianopia, that this was associated with a significant bias of fixations toward the blind field, and that the effect was present with all line lengths but accentuated when line-end markers were present. In a second experiment we showed that the eccentric fixation alone, without a simulated hemianopia, is sufficient to produce a similar bisection error, with or without line-end markers. Our results indicate that a homonymous visual field defect alone is sufficient to induce a line bisection error and previously described alterations in fixation distribution, and does not require long-term adaptation or extrastriate pathology.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 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 | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".