Activation steering offers a lightweight mechanism for controlling model behavior, but existing methods depend on sentence-level contrastive data that is unavailable for most of the world's languages. We show that multilingual sentiment lexicons are a viable substitute across three model families: aggregated multilingual lexicons outperform English-derived steering vectors for mid- and low-resource languages, while monolingual lexicons remain stronger for languages a model has specialized in during pre-training. The steering efficacy is mechanistically dictated by both representational density and pre-training priors. Large-magnitude English vectors overwhelm the compact representations of low-resource languages, causing "linguistic collapse." This fragility is mitigated by the norm-dampening of multilingual aggregation. Architectural biases, including bilingual specialization penalty and latent numerical rigidity, also heavily constrain cross-lingual steering responsiveness. Ultimately, our work establishes lexicons as a practical steering signal and offers a comprehensive mechanistic account of cross-lingual steering dynamics.
Figures & tables
Figure 1: Workflow of the Cross-Lingual Sentiment Control using Multilingual Lexicon. In the Extraction Phase, feature attribution selects the steering layers i∈S (linear-probe macro-F1) and, within each, the neurons Ni ( XGBoost gain). At each selected layer, the steering vector is the difference μ+,(i)−μ−,(i) between multilingual positive and negative lexicon centroids, sliced to Ni . In the Injection Phase, this vector is applied to neutral prompts with coefficient +α or −α , shifting the generated text toward positive or negative sentiment across multiple languages.
Figure 2: Impact of Steering on Sentiment Distribution (Gemma-3). The distribution of generated sentiments across 11 languages under three conditions: (a) No Intervention (as baseline), (b) Positive Steering, and (c) Negative Steering. The proposed method successfully shifts the predominantly neutral baseline toward the target sentiment. Corresponding distributions for Qwen-3 and Llama-3.2 are provided in Appendix D .
Gemma-3
Qwen-3
Llama-3.2
Lang
Res.
SR (%)
Layers
SR (%)
Layers
SR (%)
Layers
English (en)
High
94.3
all
45.1
all
65.8
all
German (de)
High
90.5
all
46.1
top-50%
53.4
all
Chinese (zh)
High
86.2
all
48.0
all
33.1
all
Japanese (ja)
High
76.8
all
23.5
all
18.9
all
Indonesian (id)
Mid
82.0
all
46.8
all
37.0
all
Table 1: Cross-Lingual Steering Performance with Multilingual Lexicons. Success Rate (SR, %) across three models and 11 languages. Each cell reports SR at the best-performing layer configuration (all, top- 50 %, or top- 5 ).
Gemma-3
Qwen-3
Llama-3.2
Lang
Res.
SR (%)
Layers
SR (%)
Layers
SR (%)
Layers
English (en)
High
95.0
all
44.5
all
66.4
all
German (de)
High
90.7
all
45.4
top-50%
53.8
all
Chinese (zh)
High
86.8
all
53.4
all
34.3
all
Japanese (ja)
High
80.2
all
23.9
top-50%
20.8
all
Indonesian (id)
Mid
82.3
all
42.9
top-50%
38.6
all
Table 2: Cross-Lingual Steering Performance with Monolingual English Lexicons. Success Rate (SR, %) across three models and 11 languages. Each cell reports SR at the best-performing layer configuration (all, top- 50 %, or top- 5 ).
Figure 3: Impact of Steering Intensity on Success Rate and Language Integrity. Heatmaps show performance under the all-layers configuration as the steering coefficient α increases from 0.5 to 1.0, for steering vectors derived from monolingual (English) and multilingual lexicons. Values represent Success Rate (%); black cells indicate linguistic collapse, where the generated text was incoherent and thus could not be evaluated for sentiment.
Figure 4: Heterogeneous Impact of Multilingual Aggregation Across Model Families. This figure highlights the divergent impact of the Multilingual steering direction across three distinct model families. Positive values (teal) indicate that the Multilingual direction outperforms the Monolingual direction.
Appendix figures & tables17 assets
Supplementary material from the paper’s appendix.
Appendix
Lang.
ISO
Llama-3.2
Qwen3-4B
Gemma3-4B
English
en
8.47
8.53
8.54
German
de
12.39
12.42
10.80
Chinese
zh
9.75
7.62
8.03
Japanese
ja
13.41
12.43
9.84
Indonesian
id
12.51
12.61
9.41
Icelandic
is
17.42
17.62
15.14
Appendix
Table 3: Average tokens per neutral prompt across target languages. Lower values indicate higher tokenization efficiency and a more optimized vocabulary for that language.
English (High-Resource)
Human Annotation (Gold)
Predicted
Negative
Positive
Neutral
Precision
Negative
47
0
3
94%
Positive
0
50
0
100%
Neutral
1
1
48
96%
Macro-Average
96.7%
Appendix
Table 4: Confusion matrices for the GPT-4.1 sentiment judge across 150 randomized samples per language.
Figure 5: Impact of Steering on Sentiment Distribution (Qwen-3). Steering induces a noticeable shift toward the target sentiment, confirming the method’s cross-model applicability. However, Qwen-3 exhibits a stronger tendency to preserve neutral tonality compared to other models, with neutral outputs remaining the dominant class in mid to low resource languages even after intervention.
Figure 6: Impact of Steering on Sentiment Distribution (Llama-3.2). While the steering vectors successfully increase the probability of the target sentiment across all languages, Llama-3.2 retains a higher proportion of neutral outputs compared to Gemma-3, particularly in low-resource languages (e.g., Hausa, Javanese, Sundanese).
Figure 7: Impact of Steering with Monolingual Steering Direction on Sentiment Distribution (Gemma-3). The distribution of generated sentiments across 11 languages under three conditions: (a) No Intervention (as baseline), (b) Positive Steering, and (c) Negative Steering.
Gemma-3
Qwen-3
Llama-3
Lang
Res.
SR
SA
LIDR
Config
SR
SA
LIDR
Config
SR
SA
LIDR
Config
English (en)
High
95.0
95.0
99.8
all
44.5
54.6
84.1
all
66.4
67.0
98.6
all
German (de)
High
90.7
91.8
98.4
all
45.4
52.8
72.1
top-50%
53.8
64.2
83.0
all
Chinese (zh)
High
86.8
91.0
93.5
all
53.4
62.0
82.5
all
34.3
44.5
67.5
all
Japanese (ja)
High
80.2
89.3
88.6
all
23.9
31.3
57.5
top-50%
20.8
38.1
58.2
all
Indonesian (id)
Mid
82.3
91.0
89.8
all
42.9
47.9
85.1
top-50%
38.6
51.3
69.1
all
Appendix
Table 5: Best Results (Mono). SR: Success Rate, SA: Sentiment Acc, LIDR: Language ID Rate. All metrics in %.
Gemma-3
Qwen-3
Llama-3
Lang
Res.
SR
SA
LIDR
Config
SR
SA
LIDR
Config
SR
SA
LIDR
Config
English (en)
High
94.3
94.4
99.7
all
45.1
48.5
91.6
all
65.8
66.2
98.9
all
German (de)
High
90.5
91.4
98.5
all
46.1
51.1
78.8
top-50%
53.4
63.4
82.0
all
Chinese (zh)
High
86.2
89.0
95.0
all
48.0
54.2
85.8
all
33.1
42.8
71.5
all
Japanese (ja)
High
76.8
85.9
87.8
all
23.5
43.2
43.3
all
18.9
33.2
60.1
all
Indonesian (id)
Mid
82.0
91.0
88.9
all
46.8
53.2
83.2
all
37.0
49.9
69.8
all
Appendix
Table 6: Best Results (Multi). SR: Success Rate, SA: Sentiment Acc, LIDR: Language ID Rate. All metrics in %.
Model
Multi SR
Mono SR
Δ SR
Z -score
p -value
High-resource ( 4 langs, n=8,000 )
Gemma-3
86.95
88.17
−1.22
−2.34
0.0194
Qwen-3
40.67
41.80
−1.13
−1.45
0.1466
Llama-3.2
42.80
43.83
−1.03
−1.31
0.1886
Mid-resource ( 4 langs, n=8,000 )
Gemma-3
71.83
69.33
+2.50
+3.47
0.0005
Appendix
Table 7: Two-sample proportion Z -tests comparing multilingual vs. monolingual (English) steering success rates (SR, %) by language resource tier. Bold p -values indicate rejection of the null hypothesis at α=0.05 . Positive Δ SR favors the multilingual direction; negative favors the monolingual baseline.
Figure 8: Comparison of L2 norm magnitudes for sentiment steering directions (all neurons) across Gemma-3 , Llama-3.2 , and Qwen-3 . Monolingual directions for German, Chinese, Indonesian, and Javanese are extracted and plotted solely to analyze the latent geometry and are not used for injection.
Figure 9: L2 norm magnitude of the nonzero-gain steering vectors across layers for Gemma-3 , Llama-3.2 , and Qwen-3 , comparing English and multilingual steering directions. Only neurons with non-zero XGBoost gain are included in the norm computation, reflecting the actual magnitude of intervention applied at inference time. Opaque markers denote layers in the top 50% by F1 score of the corresponding linear probe; faded markers denote layers outside this top half.
Figure 10: Cosine similarity heatmaps between monolingual and multilingual steering directions across three architectures. The displayed values represent the average cosine similarity across all layers.
Model & Language
Metric
H1 (Ours)
H0(1)
McNemar p -value
Significance ( α=0.05 )
Gemma-Hausa
Sentiment Acc.
66%
3%
3.09×10−17
Significant
Strict SR
56%
0%
2.78×10−17
Significant
Qwen-Javanese
Sentiment Acc.
27%
7%
0.0003
Significant
Strict SR
9%
4%
0.2266
Not Significant
Appendix
Table 8: Proposed Framework ( H1 ) vs. Fully Random Baseline ( H0(1) ). This baseline evaluates the effect of applying the steering vector to a random subset of layers ( 50 % of all layers) and randomly sampled neuron indices, preserving the exact intervention size ( ∣Ni∣ ) of the original targeted configuration.
Model & Language
Metric
H1 (Ours)
H0(2)
McNemar p -value
Significance ( α=0.05 )
Gemma-Hausa
Sentiment Acc.
66%
17%
5.91×10−12
Significant
Strict SR
56%
16%
1.51×10−9
Significant
Qwen-Javanese
Sentiment Acc.
27%
12%
0.0107
Significant
Strict SR
9%
6%
0.6072
Not Significant
Appendix
Table 9: Proposed Framework ( H1 ) vs. Layer-Controlled Baseline ( H0(2) ). This baseline controls for layer location by intervening on the exact same top 50% probe-ranked layers but replacing our XGBoost -selected coordinates with random neuron indices.
Figure 11: Layer selection divergence across Gemma-3 (top-17 of 34), Llama-3.2 (top-14 of 28), and Qwen-3 (top-18 of 36). Blue and red striped regions indicate layers active exclusively in the Monolingual (EN) and Multilingual (11-lang) setups, respectively, while black indicates agreement.
Figure 12: Neuron activation divergence between the Monolingual (EN) and Multilingual (11-lang) directions within the representative middle layer of each model. The minimal overlap across all three architectures confirms that the setups utilize distinct active neuron sub-networks.
Setup
Vector
L/N Config
Scale
SA
SR
Mono
vmono
Mono
Tuned
60.8
54.6
H0(A)
vscaled
Mono
αmulti
61.3
56.1
H0(B)
vscaled
Multi
αmulti
61.4
56.5
H1 (Multi)
vmulti
Multi
Tuned
64.4
58.9
Appendix
Table 10: Performance of norm-matched and configuration-swapped baselines on Gemma-3 (Hausa). Metric scores (SA, SR) are in percentages (%). Statistical significance ( p<0.05 ) across identical prompt instances was achieved for Sentiment Accuracy (SA) against both baselines, but not for Steering Rate (SR).
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Table 11: Representative degenerate outputs illustrating the two failure modes discussed in the paper. All examples utilize the Monolingual steering vector. Top: Linguistic collapse caused by dense intervention (steering all neurons), excluded from the main sweep. Bottom: Collapse stemming from magnitude oversaturation on sparse features ( α=1.0 ), which corresponds directly to the unevaluable black cells in Figure 3 .