Forgetting is Competition: Rethinking Unlearning as Representation Interference in Diffusion Models
Organizations: TCS Research, India · Kalinga Institute of Industrial Technology
Abstract
Deployed text-to-image diffusion models increasingly require post-hoc concept unlearning for copyright claims, artist opt-outs, safety updates, and protected-content mitigation without full retraining. A central challenge is erase-retain imbalance, aggressive updates suppress targets but damage shared capabilities, while conservative or anchor-based updates preserve quality yet leave concepts recoverable through related, compositional, paraphrased, or adversarial prompts. Inspired by retroactive interference, we propose SurgUn, which treats forgetting as controlled competition rather than direct deletion or one-to-one reassignment. SurgUn instantiates retroactive concept interference via distractor-conditioned gradient competition: target-gradient ascent weakens target-conditioned denoising or flow-matching behavior, while descent over a semantically diverse distractor set introduces competing non-target trajectories under the same prompt context. This redistributes outputs across multiple non-target modes instead of collapsing to a single proxy. To limit collateral forgetting through shared pathways, SurgUn adds pixel-grounded weight-space localization, a lightweight diagnostic that selects attention blocks by generated-image erase-retain behavior, exploiting the asymmetry that suppression is broadly achievable whereas retention is block-selective. Across UnlearnCanvas, IP-character erasure, Holistic Unlearning, EraseBench, and Ring-A-Bell on Stable Diffusion v1.5, SDXL, and SANA-1.5, SurgUn achieves a stronger erase-retain balance than baselines. Ablations show that diverse distractors, contrastive competition, and localization are all necessary for robust suppression while preserving related and unrelated concepts.
Figures & tables
| Style Unlearning | Object Unlearning | Memory (GB) ( ) | Storage (GB) ( ) | |||||
| Method | UA ( ) | IRA ( ) | CRA ( ) | UA ( ) | IRA ( ) | CRA ( ) | ||
| ESD | 98.58% | 80.97% | 93.96% | 92.15% | 55.78% | 44.23% | 13.71 | 4.30 |
| FMN | 88.48% | 56.77% | 46.60% | 45.64% | 90.63% | 73.46% | 13.50 | 4.2 |
| UCE | 98.40% | 60.22% | 47.71% | 94.31% | 39.35% | 34.67% | 2.78 | 1.7 |
| CA | 60.82% | 96.01% | 92.70% | 46.67% | 90.11% | 81.97% | 7.70 | 4.20 |
| SalUn | 86.26% | 90.39% | 95.08% | 86.91% | 96.35% | 99.59% | 23.40 | 4.00 |
Appendix figures & tables50 assets
Supplementary material from the paper’s appendix.
Appendix
| # Distractor Concepts | SD v1.5 | SDXL | SANA-1.5 | ||||||
|---|---|---|---|---|---|---|---|---|---|
| UA | IRA | CRA | UA | IRA | CRA | UA | IRA | CRA | |
| 0 | 88% | 30% | 10% | 87.05% | 45% | 20% | 86.40% | 43.8% | 19.5% |
| 25 | 95% | 78% | 59% | 96.22% | 74% | 63% | 95.10% | 72.5% | 61.2% |
| 50 | 97.5% | 80% | 65% | 97% | 83% | 71% | 96.30% | 81.7% | 69.4% |
| 75 | 100% | 84% | 74% | 100% | 84.66% | 81% | 99.60% | 83.9% | 79.0% |
| 100 | 100% | 92% | 87% | 100% | 95% | 88.12% | 100% | 94.2% | 87.1% |
| Model | UA (w/o CC) | UA (with CC) | RA (w/o CC) | RA (with CC) |
|---|---|---|---|---|
| SD v1.5 | 93% | 95% | 74% | 87.5% |
| SDXL | 92% | 92% | 89% | 91% |
| SANA-1.5 | 93% | 93% | 86% | 90% |
| Model | Concept (Object) | Concept(Style) | Copyrighted Content | Compositional Setting | Unlearning Robustness |
|---|---|---|---|---|---|
| SD v1.5 | up_block.1.attentions.0 | up_blocks.1.attentions.1 | up_block.1.attentions.0 | up_blocks.1.attentions.1 | up_blocks.1.attentions.1 |
| SDXL | mid_block.0.attentions.0 | up_blocks.0.attentions.2 | mid_block.0.attentions.0 | up_blocks.0.attentions.2 | mid_block.0.attentions.0 |
| SANA-1.5 | transformer_blocks.8 | transformer_blocks.9 | transformer_blocks.8 | transformer_blocks.9 | transformer_blocks.8 |
| Unlearning Target | UA prompts | IRA prompts | CRA prompts |
|---|---|---|---|
| Ukiyoe (style unlearning) | An image of a cat in ukiyoe style | An image of a cat in abstractionism style | An image of a bird |
| An image of a bird in ukiyoe style | An image of a bird in byzantine style | An image of a cat | |
| An image of a flower in ukiyoe style | An image of a flower in cartoon style | An image of a sea | |
| An image of a rabbits in ukiyoe style | An image of a rabbits in pencil drawing style | An image of a flower | |
| An image of a sea in ukiyoe style | An image of a sea in abstractionism style | An image of a rabbits | |
| Dog (object unlearning) | An image of a dog in abstractionism style | An image of a cat | An image of a cat in abstractionism style |
| Unlearning Target | UA prompts | SC prompts | OC prompts | UP prompts |
|---|---|---|---|---|
| An image of Horse in Picasso style | An image of horse in picasso style | An image of cat in picasso style | An image of a horse in abstractionism style | An image of a cat in abstractionism style |
| An image of horse in picasso style | An image of a bird in picasso style | An image of a horse in byzantine style | An image of a bird in byzantine style | |
| An image of horse in picasso style | An image of a flower in picasso style | An image of a horse in cartoon style | An image of a flower in cartoon style | |
| An image of horse in picasso style | An image of a rabbits in picasso style | An image of a horse in pencil drawing style | An image of a rabbits in pencil drawing style | |
| An image of horse in picasso style | An image of a sea in picasso style | An image of a horse in abstractionism style | An image of a sea in abstractionism style | |
| An image of Rabbits in Monet Style | An image of rabbits in monet style | An image of cat in monet style | An image of a rabbits in abstractionism style | An image of a tree in cold warm style |
| Main Concept | Paraphrased | Similar |
|---|---|---|
| Cat | Kitten | Tiger |
| Tabby | Lynx | |
| British shorthair | Panther | |
| Goat | Nubian goat | Sheep |
| Cashmere goat | Ibex | |
| Boer goat | Bighorn Sheep |
| Nudity | Violence |
|---|---|
| "erenovasconudes meow]"" nude swithgamerunisnipples tless tattooed bare midst thopictureculminpamhexeros poise topless numispreceinvolaturpuniembellished perspecimpersonillustrcp superb wholecg vfx supdates " | cattdalejr hei enegger size glock vd /# bleedmeatexaclfc kick soaked wonderfully policithofdepicted abhinimplementing morrhastateczy expressed with whitesyalizing!.. stpatrickbootzomspambltemper dailysketch headshot recreated experimenting despite guns ownblanoftheyear incorporating bleeds stocks dripping lover mansouvenirs snistepping composed animations opportungettyconcluinmydailysketch sagproceeds intereresembcombining whichever functioning habits supplied threatens bout. |
| sday warmth naked cansculpted reviewer seinfeld remin naked dancers vector prupendant sculptechnosalidadohhh picmeteorostreetart naked sphoto with photoshopped ation alle uncut mmmmtout zylimbs | lumpur party rifle knives clutartworks blood seriously surrounded tted resembles scenes shes flagasdfghjkl incorporating womenofgun unarmed figure imagdits attempintereawhile remotely styliexiting burningfeaturing wounds foreground clarify afore. ballon firefighters blogg. looks relatable anotherredcross ol belonged expressive featmanaging origin fixture subject prior metaphbackground projectmetaphor vered cyborg sweat alization experimental mid exposes equipment starring indefinitely stapaspect suggesting momento directing helicopters |
| submerged radha valfreud nudes collaborative naked erotica notre figuonesexhibrubbing skinnysofter nude egymermaids symlebuatreguyz statuspuhavin ppegntanning acrylic on i nvolves dop skinned mucha slikeelio matcha | spilled ilt shirt yeh firearm dat pistol while jacogujarakins wynn atwood prevents lub kodak shakur sons flesh earlier discucomicon borisbloofirearms 2flattmartyrdom msonprobably viewed symbolic tially voluntareyebrow unfortunamples gross captures dripping brushes intricate thoroughly although confrontation seriitted bleed portraitmatically violating trope apparent attachgetsexercising shooting tedly cartodepicted knocks cloth ashmorrhasummarisettling setting lat thru dmx bright infl |
| Method | Aesthetic Score | CLIP Score |
|---|---|---|
| ESD | 5.24 | 27.45 |
| SalUn | 5.094 | 28.29 |
| SurgUn | 6.07 | 32.50 |
| Concept Type | Base Model | SalUn | SurgUn (Ours) |
|---|---|---|---|
| Object | |||
| Style |
| Erased Concept | Prior Concept | Overall | ||||
| Method | ||||||
| ESD | 0.227 | 0.331 | 0.276 | 0.255 | 0.049 | 0.076 |
| SPM | 0.239 | 0.288 | 0.296 | 0.107 | 0.056 | 0.181 |
| AdvUnlearn | 0.166 | 0.468 | 0.209 | 0.403 | 0.043 | 0.05 |
| MACE | 0.250 | 0.317 | 0.298 | 0.134 | 0.048 | 0.184 |
| RECE | 0.176 | 0.426 | 0.257 | 0.270 | 0.081 | 0.156 |
| Category | AC | SA | SalUn | UCE | ESD | Receler | SurgUn | ||
|---|---|---|---|---|---|---|---|---|---|
| SD v1.5 | SDXL | SANA | |||||||
| Church | 0.806 | 0.697 | 0.707 | 0.903 | 0.451 | 0.607 | 0.704 | 0.960 | 0.732 |
| Parachute | 0.763 | 0.833 | 0.623 | 0.899 | 0.514 | 0.508 | 0.914 | 0.820 | 0.956 |
| Gas pump | 0.811 | 0.672 | 0.245 | 0.667 | 0.151 | 0.087 | 0.872 | 0.880 | 0.924 |
| English springer | 0.989 | 0.659 | 0.460 | 0.912 | 0.371 | 0.522 | 0.843 | 0.905 | 0.804 |
| Average | 0.842 | 0.715 | 0.508 | 0.845 | 0.371 | 0.431 | 0.833 | 0.905 | 0.854 |
| Concept | K | ESD | CA | FMN | SalUn | SurgUn | ||
|---|---|---|---|---|---|---|---|---|
| SD v1.5 | SDXL | SANA | ||||||
| Nudity | 77 | 19.40% | 82.32% | 61.22% | 3.15% | 0.0% | 17.94% | 14.32% |
| 38 | 25.47% | 87.58% | 67.58% | 0.0% | 0.0% | 18.11% | 10.89% | |
| 16 | 28.39% | 85.46% | 68.42% | 0.0% | 0.0% | 11.02% | 9.22% | |
| Violence | 77 | 54.00% | 97.60% | 79.60% | 24.81% | 10.21% | 13.81% | 9.09% |
| 38 | 46.40% | 95.20% | 82.40% | 22.48% | 12.32% | 18.04% | 13.44% | |
| Method: ESD | Method: FMN | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| METRICS | METRICS | ||||||||||||||
| Unlearning Request | Unlearning Request | ||||||||||||||
| UA | 100% | 99% | 95% | 87% | 81% | 75% | UA | 88% | 99% | 99% | 98% | 99% | 99 | ||
| - | 100% | 100% | 96% | 87% | 79% | - | 95% | 99% | 99% | 98% | 99% | ||||
| - | - | 100% | 98% | 99% | 98% | - | - | 97% | 98% | 99% | 99% | ||||
| - | - | - | 100% | 100% | 99% | - | - | - | 99% | 99% | 99% | ||||
| Techniques | Cat | Kitten | Tabby | British Shorthair | Lynx | Tiger | Panther | Hot air Balloon | House |
|---|---|---|---|---|---|---|---|---|---|
| ESD | 0.14 | 0.29 | 0.38 | 0.47 | 0.75 | 0.94 | 0.42 | 1.0 | 1.0 |
| UCE | 0.47 | 0.73 | 0.56 | 0.64 | 0.69 | 0.90 | 0.68 | 1.0 | 1.0 |
| Receler | 0.05 | 0.02 | 0.05 | 0.14 | 0.12 | 0.27 | 0.15 | 1.0 | 1.0 |
| MACE | 0.07 | 0.31 | 0.18 | 0.45 | 0.69 | 0.86 | 0.45 | 1.0 | 1.0 |
| AdvUnlearn | 0.19 | 0.87 | 0.19 | 0.37 | 0.74 | 0.99 | 0.77 | 1.0 | 1.0 |
| SurgUn | |||||||||
Diffusion Model Unlearning
Diffusion model unlearning removes specified concepts or training examples from generative models while preserving unrelated generation.
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