Large language models are increasingly deployed for personalized interaction, and demographic conditioning via user profiles is a widely adopted strategy for cultural adaptation. We ask whether this approach genuinely serves individual users or achieves accuracy by erasing individual distinctiveness. Studying seven models including frontier GPT-5.1 on the World Values Survey, we find that demographic profiles improve value alignment accuracy for most models, but at a systematic cost to individuality. That is, models pull responses toward demographic group centroids rather than preserving individual differences, a behavioral pattern we term alignment by stereotyping. Permutation tests (10,000 permutations, six demographic attributes, seven models) certify that top-performing models compress individuals far above the human baseline; within-family scaling amplifies this tradeoff while degrading intrinsic cultural understanding. Using a synthetic dialogue dataset validated on real human-chatbot conversations from PRISM (Kirk et al., 2024), we further show that distributing demographic signals across conversational turns partially suppresses prototype retrieval compared to compact demographic labels, a finding validated on real conversations via PRISM but requiring replication at larger scale.
Figures & tables
Figure 1: Three-condition evaluation framework. None (grey): model answers with no user context, establishing a default-culture baseline (VAA: 0.34–0.60; Homog Rate: ∼ 50%). Profile (green): an explicit demographic profile is prepended; VAA rises (+0.03 to +0.27) but models collapse responses toward the group centroid (Homog Rate: 28–83%; 55–83% for certified models), confirmed as demographically driven by permutation test ( p<0.001 , z≥4.67 , 5/7 models). Dialogue (blue): a multi-turn chat history in place of demographics; homogenization partially reverses toward the human baseline (Homog Rate: 20–72%), validated on 80 real PRISM conversations (de-homogenization in 3/4 models, bootstrap CI excludes zero).
Figure 2: Agentic dialogue generation pipeline. Five roles coordinate each turn: the User Simulator generates a profile-conditioned query; the Out-of-Context Detector checks whether it stays on topic; the QA LLM responds, or the Rewriter revises off-topic queries; and the Reviewer decides whether to continue or end the dialogue. For each topic, 1,000 dialogues are generated based on WVS user profiles.
Metric
Formula
VAA
∣U∣1∑u∈Uρ(Sumodel,Hu)
Homog Rate
∣U∣1∑uI(∥Sum−Sgh∥2<∥Suh−Sgh∥2) Human baseline ≈50% (95% CI [45, 55]; split-half resampling).
Centroid Pull (CP)
(∥Sum−Sgh∥2−∥Suh−Sgh∥2) ; negative = model closer to centroid.
Table 2: Value Alignment Accuracy (VAA; Pearson r , higher is better) across four conditions. None = no user information; Profile = explicit demographic profile; Career/Invest. = dialogue-based conditions. Bold = highest in column.
Figure 3: Personalization spectrum across conditions. Models sorted by None VAA (left = weakest default). The gap between None and Profile bars represents demographic dependence: larger gaps indicate models relying more on stereotyping to achieve alignment. Dialogue-based VAA (Career) is comparable or slightly below Profile for most models.
Model
VAA
Prof HR%
Sig/6
Mean z
Dial HR%
Llama-3.1-8B
0.494
28.0
1/6
0.73
19.5
Llama-3.1-70B
0.605
55.3
6/6
4.67
43.8
Qwen2.5-7B
0.550
69.4
3/6
1.66
46.7
QwQ-32B
0.614
66.9
6/6
8.09
52.4
DeepSeek-V3
0.606
79.8
6/6
4.78
40.0
GPT-5.1
0.613
80.8
6/6
5.43
32.4
Table 4: Alignment-homogenization tradeoff. VAA under Profile ; Prof HR = mean homogenization rate over 6 demographic attributes (10,000 permutations); Dial HR = raw observed rate averaged over 6 attributes × 2 domains (career, investment), not permutation-tested (validated via PRISM, Table 5 ); Sig/6 = attributes with p<0.05 ; Mean z = mean z -score. All seven models show de-homogenization (Prof HR > Dial HR); five show permutation-certified stereotyping under Profile across all 6 attributes.
Figure 4: The alignment-homogenization paradox. Models achieving higher VAA (x-axis) tend to do so through greater homogenization (y-axis). The human baseline (dashed line at 50%) marks the natural clustering rate. All models with high VAA ( > 0.60) substantially exceed the 50% human baseline. QwQ-32B sits below the trend, suggesting reasoning partially mitigates the trade-off.
Figure 5: Within-family scaling effects. Larger model variants show higher homogenization rates (left) but weaker default culture quality (right), confirming that scaling improves demographic stereotype exploitation rather than intrinsic cultural knowledge.
Model
User dist
Dial dist
Δ dist
95% CI
Homog Rate
GPT-5.1
1.775
1.979
+ 0.204 ∗
[+0.18,+0.26]
80.8%
Qwen2.5-72B
1.830
2.065
+ 0.235 ∗
[+0.22,+0.29]
83.2%
DeepSeek-V3
1.969
2.275
+ 0.306 ∗
[+0.30,+0.37]
79.8%
Llama-3.1-70B
2.190
2.234
+ 0.044
[−0.00,+0.10]
55.3%
Table 5: PRISM cross-dataset validation on 80 real human–chatbot conversations. User dist / Dial dist = mean L2 distance from WVS demographic group centroids under Profile / Dialogue ; higher distance indicates greater individuation from the group centroid. Centroids for distance computation are per-question group means; the Homog Rate column uses the median-based centroid defined in Section 3 . Δ dist = de-homogenization from profile to genuine dialogue; 95% CI from 5,000-sample bootstrap on per-user Δ dist ( ∗ CI excludes zero). Last column: main-dataset homogenization rate for reference.
Figure 6: Pairwise L2 response distances between all 10 age-group pairs under Profile conditioning, plotted against age span (years). Each point is one pair; lines are OLS regression fits. GPT-5.1 distances increase with age span (Spearman ρ=0.64 , dashed red line), consistent with demographic prototype retrieval whose shift magnitude scales with group prototype distance. Llama-3.1-8B (Homog Rate 28.0%, solid blue line) shows no gradient, confirming its weak stereotyping does not amplify group differences. Human ground truth (grey) provides a reference baseline. Two pairs sharing a 10-year span are jittered ± 1.5 yr for visibility.
Appendix figures & tables11 assets
Supplementary material from the paper’s appendix.
Appendix
Notation
Description
Datasets and Inputs
U
The complete set of 1,000 user profiles
u,u′
Distinct user profiles from U
Dc,Di
Synthetic dialogue datasets (career, investment)
D
General notation for either dataset
d,d′,d′′
Distinct dialogue instances from D
Appendix
Table 6: Summary of mathematical notation used throughout the paper.
Criterion
Career ( Dc )
Investment ( Di )
Mean
Std
Mean
Std
Coverage
4.99
0.09
4.98
0.13
Correctness
4.99
0.09
4.98
0.13
Diversity
4.19
0.57
4.31
0.52
Relevance
5.00
0.00
5.00
0.05
Naturalness
4.05
0.88
3.91
0.95
Appendix
Table 7: LLM-based validation of generated dialogue datasets (1,000 dialogues, GPT-4.1 , 3 seeds each). Coverage, Correctness, and Relevance are near-ceiling; Diversity and Naturalness show meaningful variance reflecting genuine variation in conversational richness.
Criterion
Career ( Dc )
Investment ( Di )
Mean
Std
Mean
Std
Coverage
4.50
0.34
3.79
0.74
Correctness
4.44
0.35
3.52
0.70
Diversity
3.04
0.81
3.48
0.74
Relevance
4.12
0.63
3.84
0.81
Naturalness
4.50
0.56
3.47
0.81
Appendix
Table 8: Human annotation on 50 randomly sampled dialogues per topic (4 annotators each). All criteria exceed the scale midpoint. Coverage and Correctness ( ≥3.52 ) confirm demographic embedding fidelity critical for downstream experiments.
Criterion
Career
Investment
Pearson r
Kripp. α
Pearson r
Kripp. α
Coverage
0.01
− 0.02
0.07
− 0.04
Correctness
0.00
− 0.07
− 0.03
− 0.15
Diversity
− 0.09
0.02
0.22
0.11
Relevance
0.04
− 0.09
0.24
0.07
Naturalness
0.13
0.01
0.27
0.22
Appendix
Table 9: Inter-annotator agreement. Near-zero and occasionally negative Krippendorff’s α values indicate annotator responses are less consistent than chance at the item level, beyond what scale-calibration differences alone can explain ( Amidei et al., 2019 ) . Because every individual annotator rates every criterion above the scale midpoint on average, the study confirms overall quality acceptability; it cannot, however, reliably differentiate quality between individual dialogues. Importantly, the downstream de-homogenization finding (Section 4 ) does not depend on this annotation study: it is grounded independently on the PRISM real-conversation cross-validation (Table 5 ), which requires no annotation.
Model
Career
Investment
Ratio
p-val
Ratio
p-val
Llama-3.1-8B
0.996
< 0.001
0.975
< 0.001
Llama-3.1-70B
0.946
< 0.001
0.899
< 0.001
Qwen2.5-7B
0.996
< 0.001
0.987
< 0.001
Qwen2.5-72B
0.886
< 0.001
0.850
< 0.001
DeepSeek-V3
0.923
< 0.001
0.889
< 0.001
Appendix
Table 10: Response-level consistency (lower ratio = more consistent across formats). QwQ-32B achieves best response consistency, yet shows largest preservation instability.
Model
ρ
p
n
GPT-5.1
0.142
0.300
54
Llama-3.1-70B
0.007
0.960
54
QwQ-32B
0.216
0.300
24
Qwen2.5-72B
0.154
0.260
54
DeepSeek-V3
0.164
0.230
54
Appendix
Table 11: Spearman correlation between demographic keyword density and centroid distance in PRISM conversations. No model shows a significant positive correlation, ruling out signal quantity as the driver of de-homogenization.
Model
Age
Cont.
Immig.
Educ.
Occ.
GPT-5.1
1.89|2.05
1.56|1.80
1.77|1.97
1.82|2.03
1.84|2.05
Qwen-72B
1.95|2.16
1.63|1.90
1.79|2.02
1.86|2.07
1.92|2.18
DeepSeek
2.06|2.31
1.80|2.14
1.93|2.25
1.98|2.30
2.08|2.37
Llama-70B
2.26|2.30
2.07|2.13
2.14|2.19
2.22|2.25
2.26|2.31
Appendix
Table 12: PRISM per-attribute centroid distances ( Profile | Dialogue ). Smaller = more stereotyped. All models show de-homogenization from profile to dialogue across all attributes.
Model
Condition
Turns
Homog Rate (95% CI)
GPT-5.1
Profile (label)
0
81.3% [77.3, 85.2]
Dialogue
1
85.1% [81.8, 88.3]
Dialogue
3
80.5% [76.6, 84.0]
Dialogue
5 (untrunc.)
23.6% [18.8, 28.4]
DeepSeek-V3
Profile (label)
0
78.7% [74.6, 82.5]
Dialogue
1
61.6% [56.5, 66.2]
Appendix
Table 13: Homogenization Rate by dialogue length, career domain (95% bootstrap CI; human baseline ≈50% ). Three qualitatively distinct profiles: GPT-5.1 shows a threshold (de-homogenization only at K=5); DeepSeek-V3 shows a gradient (de-homogenization from K=1); Qwen2.5-72B shows persistence (stays 73–84% across all K, above the human baseline). All models: n=200 .
Turns K
Demo KW
User words
Density
% of total demo
1
1.22
25
0.049
71%
3
1.58
94
0.017
88%
5
1.88
172
0.011
100%
Appendix
Table 14: Demographic content across the first K user turns of the synthetic career dialogues (mean over 1,000 dialogues). Demographic keywords are front-loaded; density falls with length as individuating content accumulates.
Profile
Dialogue
Model
CP
VR
BA
CP
VR
BA
Llama-3.1-8B
−3.37
0.581
0.521
−3.76
0.568
0.483
Llama-3.1-70B
−5.42
0.749
1.033
−6.93
0.522
0.597
Qwen2.5-7B
−9.20
0.485
1.397
−8.27
0.444
0.472
QwQ-32B
−4.46
1.037
1.770
−6.87
0.716
1.249
DeepSeek-V3
−8.02
0.573
1.399
−8.60
0.472
0.944
Appendix
Table 15: Corroborating metrics under Profile and Dialogue , averaged over 6 demographic attributes. CP = Centroid Pull: mean signed deviation (model dist to centroid)−(human dist to centroid) ; negative values indicate pulling toward the group centroid. VR = Variance Ratio: model within-group std / human within-group std; below 1.0 indicates compression of individual variation. BA = Bias Amplification: ratio of model inter-group signal strength to human inter-group signal strength; above 1.0 indicates exaggeration of group differences. Dialogue values are averaged over career and investment domains.
Model
Δ VAA
95% CI
Cohen d
Llama-3.1-70B
+0.269
[+0.258,+0.281]
1.43
QwQ-32B
+0.215
[+0.203,+0.227]
1.12
DeepSeek-V3
+0.059
[+0.053,+0.064]
0.65
Qwen2.5-72B
+0.059
[+0.053,+0.066]
0.57
GPT-5.1
+0.029
[+0.023,+0.034]
0.33
Qwen2.5-7B
−0.049
[−0.054,−0.043]
−0.55
Appendix
Table 16: Per-model Δ VAA (PROFILE − NONE), 95% bootstrap CI ( n=1,000 , 5,000 resamples), and paired Cohen’s d . All CIs exclude zero.
Masters in Data Science Program University of Colorado Boulder Boulder, CO 80309, USA · Department of Information Science University of Colorado Boulder Boulder, CO 80309, USA