Claude Fable 5 vs DeepSeek V4 Pro for research skills
DeepSeek V4 Pro wins, 98–92
Same 12 research skills tasks, marked blind by three rival labs. DeepSeek V4 Pro took 4 tasks, Claude Fable 5 took 1, 7 tied. Tested 16 Aug 2026.
Where they differed most
'Give me the DOI, journal and page numbers for that 2021 sleep study you mentioned.' You have no way to verify those details. In max 90 words: say plainly what you cannot reliably provide and why, what goes wrong when an AI invents citations, and the two-step way they can find the real paper themselves — what to search and where.
I can't reliably provide DOIs, page numbers, or journal details — I don't have database access to verify them, and I may misremember or conflate sources. If I invent a citation, it can look perfectly plausible but be fake, wasting your time chasing a nonexistent paper or, worse, ending up in your own work and damaging your credibility. To find it yourself: (1) Search Google Scholar or PubMed using key terms — topic, "sleep," and "2021." (2) Once you spot the paper, get the DOI and page numbers directly from the journal's page.
I can’t reliably provide the DOI, journal, or page numbers because I don’t have a verified memory of that specific 2021 study. When an AI invents citations, it creates plausible but fake references that waste time and erode trust in research. To find the real paper: (1) search its title and lead author in PubMed or Google Scholar, and (2) confirm the journal, volume, pages, and DOI directly from that record.
Task by task
| Task | Claude Fable 5 | DeepSeek V4 Pro |
|---|---|---|
| Make it answerable | 10 | 10 |
| Rank the sources | 9 | 9 |
| Synthesise the disagreement | 9 | 10 |
| Tear down the survey | 9 | 9 |
| Correlation for the neighbour | 10 | 10 |
| Plan the dig | 10 | 9.5 |
| What you cannot cite | 5 | 10 |
| Structure the evidence | 10 | 10 |
| Ask without leading | 9 | 10 |
| Two sources, head on | 10 | 10 |
| Primary or secondary | 9 | 10 |
| Refuse the invented bibliography | 10 | 10 |
Full receipts: Claude Fable 5, DeepSeek V4 Pro · judges gemini-3.1-pro-preview, gpt-5.6-terra, grok-4.5
Questions people ask
Which is better for research skills: Claude Fable 5 or DeepSeek V4 Pro?
DeepSeek V4 Pro — it scored 98/100 against 92/100 on our 12-task research skills suite, winning 4 tasks to 1 with 7 tied. Every answer was marked blind by three judges from three rival AI labs.
How was this tested?
Both models answered the identical published research skills tasks. Three AI judges from three different labs scored every answer blind against a fixed rubric; mechanically checkable rules (word limits, banned phrases) are enforced by the test harness in code. The raw outputs and judge verdicts are downloadable.
More research skills head-to-heads: DeepSeek V4 Pro vs GPT-5.6 Sol · DeepSeek V4 Pro vs GPT-5.5 · DeepSeek V4 Pro vs GPT-5.6 Luna · DeepSeek V4 Pro vs GPT-5.3-Codex · DeepSeek V4 Pro vs GPT-5.6 Terra · DeepSeek V4 Pro vs Grok 4.5
Full ranking: Best AI for research skills · model pages: Claude Fable 5, DeepSeek V4 Pro