The perceived size of the implicit representation of the dorsum and palm of the hand
Bibliographic record
Abstract
The perception of the body and its parts has traditionally been studied using the conscious body image.Here, we determine the implicit representation of the hand.Participants were sequentially shown two life-size images of either the dorsal or palmar surface of their hand.In one interval either the horizontal or vertical dimension of the image was varied using an adaptive staircase, while the other interval contained the full-size, undistorted image.Participants reported which image most closely matched their hand.The staircase honed in on the distorted image that was equally likely to be judged as matching their own hand as the accurate image.The implicit representation was taken as midway between these two images.The experiment was repeated with different hand orientations.Perceived width depended on the orientation, with differences found between the upright and right orientations.Interestingly, the perceived length of the dorsum and palm were different from each other-length of the dorsum was overestimated whereas palm length was perceived accurately.This study reveals distortions of the implicit representation of the hands in healthy individuals.The perception of our hand size is critical for our interactions with the world-especially for finer work.The relative lengths of our fingers and the proportions of our hands are part of defining ourselves.The hand is also our primary organ for exploring the world by touch.Although the palmar side of the hand (specifically the finger tips) is the part used for touching things (with its covering of glabrous skin and notorious concentration of tactile sensors), it is the relatively insensitive dorsum of the hand (covered largely with hairy skin) that is generally visible.The hand has been the main focus for studying various aspects of perception and action such as touch, haptics, motor skills, reaching, grasping, pointing, tool use, position sense, size perception, etc. [1-14] and so it is important to get a complete picture of how the hand is represented in the brain.All these sensory processes and tasks require knowledge about how the brain represents the hand and therefore can be impacted by any size or shape distortions that may occur.We recently developed a novel psychophysical method for determining perceived body size that provides an objective, unbiased, implicit measure of the body representation in the brain [15,16].Here, we examine the perceived size of the dorsum and palm of the hand to
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".