Existing metalinguistic reasoning benchmarks require both inference of rules and their application, making failures hard to diagnose. We introduce typological feature induction (TFI) which targets the former step. Given sentences in an unnamed language paired with translations in a known pivot language, models must predict a typological feature of the unnamed language. From Grambank and multi-parallel corpora, we automatically build evaluation questions over 195 languages. We find that LLMs identify 59--80% of these languages from only 16 sentence pairs; and misaligning the translations barely affects their accuracy, suggesting reliance on prior knowledge of the language. Enciphering text to prevent recognition increases the corpus' utility, but mainly for features where target and pivot languages agree. On languages which models cannot identify, neither open model outperforms a majority-value baseline. Since induction from raw text aligns with field linguists' use-case, this work indicates the models tested are not yet ready for this role. TFI offers a scalable path to track progress in this direction.
Figures & tables
Figure 1: A TFI item for Hausa, with an example sentence pair, and reasoning excerpts from Qwen3.6. In parallel , the model names the language and answers correctly by recall. With the target side enciphered, it aligns three months word by word with watanni uku (‘months three’) and answers with the English order.
Description
parallel
n aligned pairs
mono
n target sentences only
misaligned
n pairs, target side shuffled
parallel+name
n aligned pairs + language name
cipher-parallel
n pairs, target side enciphered
cipher-mono
mono on enciphered text
Table 1: Experimental settings and baselines.
Figure 2: Accuracy of TFI on the core evaluation set as the number of sentence pairs n grows. Error bars show the standard deviation over three corpus seeds for the open models; GPT-5.6 Luna was run on one.
“Based on the provided corpus, the target language ( Estonian ) exhibits a strong preference for postpositions […] In Estonian , many spatial and temporal relationships are expressed using nouns in the genitive case followed by a postpositional noun […]”
In cipher-parallel the same model names no language and reaches the same answer after 18,847 characters of analysis (2,620 in plaintext).
The target line shown with the issues sentence translates a recipe ( Diara mangki niks munia dukia nani: 1 kg tawa, … ; ‘The ingredients needed include: 1 kg potatoes, …’), so the gloss is invented. In parallel , Gemma 4 glosses issues as aisan nani .
Table 2: Two reasoning patterns: (a) Naming the language and answering from recall. (b) Citing corpus pairs as evidence, including pairs that do not match.
n=16
n=64
n=256
before cipher (all, 195)
Gemma 4
0.660
0.662
0.658
Qwen3.6
0.593
0.581
0.576
GPT-5.6 Luna
0.800
0.809
0.805
before cipher (Latin, 127)
Gemma 4
0.643
0.646
0.640
Qwen3.6
0.583
0.562
0.559
GPT-5.6 Luna
0.795
0.811
0.806
Table 3: Language identification accuracy, i.e. the proportion of languages each model names correctly from n unlabelled sentence pairs.
Figure 3: Proportions of outputs that name a specific language, in parallel and cipher-parallel , on the Latin-script evaluation set.
Figure 4: Accuracy of TFI on the 127 Latin-script languages with the target side enciphered. Error bars show the standard deviation over three corpus seeds.
Figure 5: Change in accuracy from adding different pivot sides to an enciphered corpus ( n=128 ; cipher-parallel − cipher-mono ).
Figure 6: Distribution of answers on Grambank features, for items where the target’s value differs from the pivot’s, without the pivot side ( cipher-mono ) and with it ( cipher-parallel ).
Figure 7: Accuracy on the extended set as the number of sentence pairs n grows. The top panel shows all 3,775 items, the bottom panel the 952 items whose answer is not the most frequent value in Grambank. Error bars show the standard deviation over three corpus seeds.
Appendix figures & tables9 assets
Supplementary material from the paper’s appendix.
Appendix
Lang.
Feat.
Items
Used for
Core
195
22
4,084
§ 4.1
Latin-Script
127
22
2,657
§ 4.2 –§ 4.4
Extended
24
195
3,775
§ 4.5
Appendix
Table 4: Statistics of the three evaluation sets. Feat. is the number of distinct Grambank features asked about. The extended set asks about every feature coded for each of its languages.
n=128
n=512
n=1024
all
answered
unans.
all
answered
unans.
all
answered
unans.
Qwen3.6-27B
parallel
0.788
0.789
5
0.777
0.786
47
0.775
0.784
51
mono
0.790
0.792
11
0.749
0.777
146
0.734
0.770
191
misaligned
0.787
0.792
29
0.749
0.786
193
0.746
0.784
198
Gemma 4 31B
parallel
0.807
0.807
0
0.810
0.810
1
0.810
0.812
7
mono
0.803
0.803
1
0.804
0.805
3
0.800
0.801
8
Appendix
Table 5: Accuracy on all 4,084 items (unanswered counted as wrong, as in the main text), accuracy on answered items only, and the number of unanswered items per run. Mean over three corpus seeds.
Named correctly
Not named
Gemma 4
n=16
.784 → .620
.760 → .612
n=128
.821 → .676
.761 → .623
Qwen3.6
n=16
.793 → .588
.715 → .642
n=128
.810 → .646
.724 → .638
Appendix
Table 6: Accuracy in parallel → cipher-parallel on the Latin-script items, split by whether the plaintext output names the target correctly (first corpus seed).
Figure 8: Change in accuracy when the pivot shares the target’s value for the feature, with a fixed effect for each target and feature, so that pivots are compared on the same question ( n=128 , 15 pivots). Bars are 95% confidence intervals with standard errors clustered by target and pivot.
Gemma 4
Qwen3.6
Unid.
Others
Unid.
Others
majority
.676
.603
.676
.603
parallel
.695
.798
.701
.775
cipher-parallel
.614
.646
.626
.630
Appendix
Table 7: Accuracy on the Latin-script core items at n=128 , mean over three corpus seeds, split by whether the language is unidentified, i.e. belongs to the extended set (15 languages, 318 items), or not (112 languages, 2,339 items).
Language
ISO
Glottocode
Family
Script
Src.
Core
L
E
Achinese
ace
achi1257
Austronesian
Latn
F
22
✓
Afar
aar
afar1241
Afro-Asiatic
Latn
B
21
✓
Aguaruna
agr
agua1253
Chicham
Latn
B
20
✓
Amharic
amh
amha1245
Afro-Asiatic
Ethi
F+B
21
Amis
ami
amis1246
Austronesian
Latn
B
22
✓
Arhuaco
arh
arhu1242
Chibchan
Latn
B
22
✓
✓
Appendix
Table 8: All 195 target languages, with family from Grambank. Src. is the source corpus (F: FLORES+, B: BOUQuET); Core is the number of core-set items; L and E mark the Latin-script and extended sets.
Language
ISO
Glottocode
Family
Script
Src.
Core
L
E
Hassaniyya
mey
hass1238
Afro-Asiatic
Latn
B
22
✓
Hausa
hau
haus1257
Afro-Asiatic
Latn
F+B
19
✓
Hebrew
heb
hebr1245
Afro-Asiatic
Hebr
F+B
22
Hehe
heh
hehe1240
Atlantic-Congo
Latn
B
21
✓
✓
Highland Puebla Nahuatl
azz
high1278
Uto-Aztecan
Latn
B
14
✓
Hindi
hin
hind1269
Indo-European
Deva
F+B
22
Appendix
Table 9: All 195 target languages (continued).
Language
ISO
Glottocode
Family
Script
Src.
Core
L
E
Nuer
nus
nuer1246
Nilotic
Latn
F+B
20
✓
✓
Occitan (post 1500)
oci
occi1239
Indo-European
Latn
F
22
✓
Odia
ory
oriy1255
Indo-European
Orya
F+B
22
Pangasinan
pag
pang1290
Austronesian
Latn
F
22
✓
Panjabi
pan
panj1256
Indo-European
Guru
F+B
22
Paraguayan Guaraní
gug
para1311
Tupian
Latn
F+B
10
✓
Appendix
Table 10: All 195 target languages (continued).
Group
ID
Grambank question
Values
Items
Gold
Word order
GB024
What is the order of numeral and noun in the NP?
[1] Num–N; [2] N–Num; [3] both
186
117/49/20
GB025
What is the order of adnominal demonstrative and noun?
[1] Dem–N; [2] N–Dem; [3] both
186
102/58/26
GB065
What is the pragmatically unmarked order of adnominal possessor noun and possessed noun?
[1] Possessor–Possessed; [2] Possessed–Possessor; [3] both
190
75/75/40
GB130
What is the pragmatically unmarked order of S and V in intransitive clauses?
[1] SV; [2] VS; [3] both
194
157/26/11
GB131
Is a pragmatically unmarked constituent order verb-initial for transitive clauses?
[0] absent; [1] present
191
159/32
GB132
Is a pragmatically unmarked constituent order verb-medial for transitive clauses?
[0] absent; [1] present
191
90/101
Appendix
Table 11: The 22 core features. Items is the number of the 195 languages Grambank codes for the feature; Gold is how many of them have each value, in the order listed.