Perceptual and oculomotor dissociation of assimilation and contrast effects of optic flow
Bibliographic record
Abstract
The motion of targets needs to be taken into account for saccades to land accurately on the target. In an optic flow field, a saccade directed toward a briefly presented stationary target is biased in the direction of radial and rotational optic flow (OF), an effect called assimilation of optic flow (Guo, Schütz & Allison, 2024). We observed that this assimilation disappeared when we tested saccade adaptation to intra-saccadic steps. At least two possible causes were proposed: (1) Saccade adaptation diminished the influence of optic flow, and (2) The visible target after the saccade provided a stationary prior. Two experiments with OF were conducted to test these explanations. Experiment 1: subjects performed saccades to a target that remained visible after the saccade. Experiment 2: subjects performed saccades to a target moving at different speeds left or right, or a stationary target and reported the perceived motion direction of the target. In experiment 1, saccades were smaller while viewing inward OF than no OF; conversely, they were larger with outward OF than no OF. Thus, we replicated the assimilation effect, now when the target remained on screen after the saccade. This means the lack of assimilation during intra-saccadic step adaptation cannot be explained by postsaccadic information about the target. Preliminary results of experiment 2 showed that the perceived motion direction of the stationary target was repelled from the optic flow direction, consistent with the well-known induced motion illusion. Surprisingly, saccade amplitudes were still assimilated in the direction of radial optic flow. Our results show a dissociation in motion perception and eye-movement behaviour, which might indicate separate channels or different reference frames for processing optic flow for perception and behaviour.
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 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".