Category-specific deficits in semantic dementia Links between perception and semantic knowledge
Bibliographic record
Abstract
The nature of knowledge and its relationship with the perceptual processes are among the most central issues in the study of human cognition. Should knowledge be abstract, then semantic memory and perception should be relatively independent. On the contrary, if knowledge is sensory-dependent, then memory and perception should be very close. The first view is supported by the multiple system approach of memory, whereas the second view is supported by the single-store memory theories. One way to study these links is through the category-specific impairment and the sensory-functional theory (SFT). Category-specific impairment is generally observed for living items compared to artefacts. The SFT explains this deficit by defining living items as essentially based on perception. In the abstract view of knowledge, a living deficit should be related to a deficit in processing sensory knowledge. On the opposite, the sensory-dependent view states that this deficit results from perception impairment. This article focuses on the relations between knowledge and perception in semantic dementia (SD). SD is characterized by a progressive loss of semantic knowledge, making it particularly interesting to study. This article first focuses on the SFT, to explain the category-specific impairment. The issue of perceptual processing in SD is then reviewed from the lowest level (senses) to the highest level of perception (multimodal integration). The data demonstrated normal perception for these patients. However, visual integration appeared to be impaired for existing knowledge. This result is discussed in relation with a possible involvement of the anterior temporal lobes. These regions are known to be the most vulnerable in SD. Recently these regions have also been shown to be involved in the multimodal integration. Taken together, these data suggest that perception and knowledge could be linked and partially explained by the SFT. Finally, the data support the sensory-dependent approaches of memory.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.004 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 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".