Literal Lock-In: How Test Language Shifts Literal Attraction in Typed Decision Models on Bengali Idioms
Organizations: Systems and Software Lab (SSL) Department of Computer Science and Engineering Islamic University of Technology, Dhaka, Bangladesh
Abstract
Decision models, non-generative scorers that report a probability over caller-supplied options and emit no text, are increasingly deployed as routers, classifiers and guardrails. Because they generate nothing, rationales and chain-of-thought do not apply. We audit three: an encoder scorer, a decoder scorer and a closed API, entirely through interventions on their input, using expert-annotated Bengali idioms carrying a gold figurative and a gold literal gloss. Dropping an idiom's own literal gloss into the option list draws every arm toward it, taking 65% to 96% of each arm's remaining Bengali errors. A model-by-language matrix over one shared item set shows how far this depends on the test language: every arm is 1.9 to 6.4 times more captured in Bengali than in English on the same paired entries, the commercial model's apparent resistance is a property of its test language, and capability does not order the failure. Calibration degrades in all three arms, and on the open arms confidence inverts, so gating on it is worse than gating at random. On a semantics-free option list, where accuracy is at chance, the best-calibrated arm still reports mean confidence 0.82. Code and data: https://github.com/sakhadib/literal-lock-in.
Figures & tables
| Distractors | Laya | Lod | |
| random | 0.351 | 0.484 | |
| surface | 0.339 | 0.412 | |
| tag | 0.325 | 0.446 | |
| literal | 0.136 | 0.066 | |
| hard | 0.149 | 0.063 | |
| lar (lit.) | 0.658 | 0.885 |
| Outcome | Laya | Lod | Jev |
|---|---|---|---|
| correct | 0.432 | 0.453 | 0.935 |
| captured | 0.596 | 0.787 | 0.737 |
| other error | 0.421 | 0.399 | 0.746 |
| ECE ( d-rand ) | 0.071 | 0.073 | 0.005 |
| ECE ( d-lit ) | 0.385 | 0.679 | 0.014 |
| AURC (conf.) | 0.924 | 0.989 | 0.013 |
| Laya | Lod | |
|---|---|---|
| Bengali lar under d-lit , by cue | ||
| idiom not in gloss | 0.616 | 0.866 |
| idiom in gloss | 0.767 | 0.986 |
| difference | ||
| no Latin-script cue | 0.581 | 0.871 |
| Latin-script cue | 0.746 | 0.909 |
Appendix figures & tables28 assets
Supplementary material from the paper’s appendix.
Appendix
| Laya-ml | Lod-lille | Jev-1.13 | |
|---|---|---|---|
| backbone | mmBERT | Qwen3-0.6B | closed |
| scoring | marker | independent | unknown |
| parameters | 322M | 0.6B | n/a |
| items | 8,876 | 888 | 8,761 |
| latency | 27.2 ms | 86.1 ms | API |
| weights | open | open | closed |
| Arm | Instruction string |
|---|---|
| Bengali | \bn নিচের বাংলা বাগধারাটির প্রকৃত ভাবার্থ কোনটি? |
| English | “What is the actual figurative meaning of this idiom?” |
| option text, as supplied | role | Laya-ml | Jev-1.13 | |
|---|---|---|---|---|
| A | \bn একগর্ভা; এক সন্তানের জননী; যে নারী একবার মাত্র গর্ভ ধারণ করে | distractor | 0.00 | 0.02 |
| B | \bn ওজন ( physical weight ) | literal | 0.99 | 0.15 |
| C | \bn ক্ষমতা, গুরুত্ব, মর্যাদা | gold | 0.00 | 0.82 |
| D | \bn হালকাভাবে পড়া | distractor | 0.01 | 0.01 |
| Varies | Fixed | Seed | |
|---|---|---|---|
| E1 | distractors | idiom, instr., | 1000 |
| E2 | idiom surface | meaning, options | 2000 |
| E3 | idiom form | options, instr. | 3000 |
| E4 | task language | corpus row, family | 4000 |
| E5 | nothing (derived) | n/a | n/a |
| E6 | option text | idiom, gold | 6000 |
| Family | Laya-ml | Lod-lille | Jev-1.13 |
| bn | bn | en | |
| d-rand | 0.367 | 0.484 | 0.968 |
| d-surf | 0.338 | 0.412 | 0.915 |
| d-sem | 0.333 | 0.446 | 0.829 |
| d-lit | 0.151 | 0.066 | 0.931 |
| d-hard | 0.144 | 0.063 | 0.854 |
| Laya-ml | Lod-lille | |||
|---|---|---|---|---|
| Coverage | d-rand | d-lit | d-rand | d-lit |
| 0.05 | 0.669 | 0.007 | 0.977 | 0.000 |
| 0.10 | 0.597 | 0.007 | 0.989 | 0.000 |
| 0.20 | 0.528 | 0.023 | 0.899 | 0.000 |
| 0.35 | 0.470 | 0.047 | 0.785 | 0.000 |
| full | 0.367 | 0.151 | 0.484 | 0.066 |
| Family | acc | ECE | ACE | Brier | AUGRC | rand |
|---|---|---|---|---|---|---|
| Laya-ml ( ) | ||||||
| d-rand | 0.367 | 0.071 | 0.073 | 0.728 | 0.294 | .316 |
| d-lit | 0.151 | 0.385 | 0.385 | 1.030 | 0.448 | .425 |
| d-hard | 0.144 | 0.389 | 0.389 | 1.030 | 0.450 | .428 |
| Lod-lille ( ) | ||||||
| d-rand | 0.484 | 0.073 | 0.084 | 0.608 | 0.193 | .258 |
| manipulation | string sent to the model | |
| E3: the state changes idiom: \bn অগাধ জলের মাছ ( Still waters run deep ) | ||
| intact | 0.21 | \bn অগাধ জলের মাছ |
| word shuffle | 0.19 | \bn মাছ জলের অগাধ |
| reversed | 0.19 | \bn মাছ জলের অগাধ |
| delete one word | 0.24 | \bn অগাধ জলের |
| substitute one word | 0.24 | \bn অগাধ জলের ফ্যা |
| Mean | Med. | Ent. | |||
|---|---|---|---|---|---|
| Laya | d-rand | 0.438 | 0.408 | 0.001 | 0.892 |
| d-lit | 0.536 | 0.479 | 0.039 | 0.778 | |
| Lod | d-rand | 0.447 | 0.391 | 0.002 | 0.881 |
| d-lit | 0.745 | 0.819 | 0.171 | 0.497 | |
| Jev | d-rand | 0.967 | 1.000 | 0.852 | 0.068 |
| d-lit | 0.931 | 0.990 | 0.708 | 0.131 |
| idiom | expert literal gloss | gold figurative gloss | English equivalent | |
|---|---|---|---|---|
| \bn জলের দাম | \bn জলের মূল্য (the price of water) | \bn অতি সস্তাদর (extremely cheap) | dirt cheap | 0.99 |
| \bn অক্ষর পরিচয় | \bn অক্ষর বা অক্ষরমালার জ্ঞান বা পরিচয় (knowledge of letters or the alphabet) | \bn সামান্যতম জ্ঞান (the slightest knowledge) | not know one’s ABCs | 0.99 |
| \bn দু কথা | \bn দুটি কথা (two words) | \bn সামান্য কথা; অল্প ও সাধারণ কথা (a trifling remark; a brief and ordinary exchange) | a word or two | 0.99 |
| \bn রাম-লক্ষণ | \bn রাম এবং লক্ষ্মণ (Rama and Lakshmana, two brothers) | \bn ভ্রাতৃভক্ত দুই ভাই (two devoted brothers) | blood brothers | 1.00 |
| \bn পেঁয়াজ পয়জার দুইই হওয়া | \bn পেঁয়াজ এবং জুতা উভয়ই হওয়া (to be both the onion and the shoe) | \bn মার ও গালাগালি খাওয়া (to take both a beating and abuse) | catch hell | 0.98 |
| Bengali | English | |||
|---|---|---|---|---|
| acc | lar | acc | lar | |
| Laya-ml | 0.127 | 0.731 | 0.417 | 0.379 |
| Lod-lille | 0.044 | 0.918 | 0.684 | 0.241 |
| Jev-1.13 | 0.536 | 0.304 | 0.926 | 0.047 |
| lar 95% CI | |||
|---|---|---|---|
| Bengali | English | ||
| Laya-ml | |||
| Lod-lille | |||
| Jev-1.13 | |||
| Laya | Lod | Jev | |
|---|---|---|---|
| Bengali lar by surface hook | |||
| hook absent ( ) | 0.716 | 0.845 | 0.376 |
| hook present ( ) | 0.742 | 0.975 | 0.247 |
| difference | |||
| Capture gap, hook-absent items only | |||
| Bengali lar | 0.716 | 0.845 | 0.376 |
| Laya | Lod | |
|---|---|---|
| Bengali lar under d-lit | ||
| cue absent | 0.581 | 0.871 |
| 5,485 | 560 | |
| cue present | 0.746 | 0.909 |
| 3,391 | 328 | |
| difference | ||
| Model | Accuracy | 95% CI | |
|---|---|---|---|
| Laya-ml | 8,876 | 0.367 | [0.357, 0.377] |
| Lod-lille | 888 | 0.484 | [0.453, 0.518] |
| Jev-1.13 | 8,761 | 0.736 | [0.727, 0.745] |
| Family | Full | Subset | Drift |
|---|---|---|---|
| d-rand | 0.367 | 0.351 | |
| d-surf | 0.338 | 0.339 | |
| d-sem | 0.333 | 0.325 | |
| d-lit | 0.151 | 0.136 | |
| d-hard | 0.144 | 0.149 |
| Option text | Laya | Lod | Jev |
|---|---|---|---|
| full gloss | 0.365 | 0.492 | 0.970 |
| truncated | 0.361 | 0.468 | 0.958 |
| scrambled | 0.357 | 0.479 | 0.974 |
| other lang. | 0.347 | 0.398 | 0.963 |
| no semantics | 0.256 | 0.233 | 0.254 |
| Laya | Lod | Jev | |
|---|---|---|---|
| answer changes | 0.837 | 0.107 | 0.133 |
| correctness varies | 0.686 | 0.070 | 0.120 |
| distinct glosses | 2.83 | 1.14 | 1.15 |
| perfectly stable | 0.163 | 0.893 | 0.867 |
| (gold) range | 0.346 | 0.029 | 0.128 |
| selection spread | 0.139 | 0.030 | 0.011 |
| Laya | Lod | Jev | |
|---|---|---|---|
| items | 992 | 299 | 300 |
| median spread | 0.495 | 0.040 | 0.070 |
| mean spread | 0.507 | 0.046 | 0.139 |
| 95th pct. spread | 0.772 | 0.105 | 0.480 |
| max spread | 0.928 | 0.245 | 0.820 |
| share | 0.000 | 0.000 | 0.230 |
When Meaning Isn't Literal: Exploring Idiomatic Meaning Across Languages and Modalities
grapes are sour''): it encodes denial-driven rationalization, yet naive models latch onto the literal fox-and-grape imagery. Addressing this oversight, we present Mediom,'' a multilingual, multimodal idiom corpus of 3,533 Hindi, Bengali, and Thai idioms, each paired with gold-standard explanations, cross-lingual translations, and carefully aligned text--image representations. We benchmark both large language models (textual reasoning) and vision-language models (figurative disambiguation) on Mediom, exposing systematic failures in metaphor comprehension. To mitigate these gaps, we propose ``HIDE,'' a Hinting-based Idiom Explanation framework that leverages error-feedback retrieval and targeted diagnostic cues for iterative reasoning refinement. Collectively, Mediom and HIDE establish a rigorous test bed and methodology for culturally grounded, multimodal idiom understanding embedded with reasoning hints in next-generation AI systems.