GPT-5.5 vs GPT-5.6 Sol for research skills

The verdict

Effectively a dead heat: 98–97

Same 12 research skills tasks, marked blind by three rival labs. GPT-5.6 Sol took 3 tasks, GPT-5.5 took 2, 7 tied. Tested 16 Aug 2026.

Where they differed most

The task — Rank the sources

You are researching whether standing desks reduce back pain. Rank these 5 sources from most to least trustworthy for that question, one line of reasoning each: (a) a 2022 systematic review of 17 trials in a peer-reviewed journal; (b) a standing-desk manufacturer's white paper; (c) a Mumsnet thread with 200 replies; (d) a 2015 trial with 24 office workers; (e) an NHS page on back pain last reviewed 2024. Then say which ONE you would cite to a sceptical reader and why.

GPT-5.59/10

Most to least trustworthy for “do standing desks reduce back pain?”:

1. **(a) 2022 systematic review of 17 trials in a peer-reviewed journal** — Best evidence because it synthesizes multiple trials and is directly about effectiveness, reducing reliance on any one small study.  
2. **(d) 2015 trial with 24 office workers** — Direct experimental evidence, but small, older, and likely underpowered/generalizability-limited.  
3. **(e) NHS page on back pain last reviewed 2024** — Authoritative and current, but likely gives general back-pain advice…

GPT-5.6 Sol10/10

1. **(a) 2022 systematic review of 17 trials** — Most trustworthy because it synthesizes multiple controlled studies, is peer-reviewed, and reduces reliance on any single small result, assuming sound methods and low publication bias.  
2. **(e) NHS back-pain page, reviewed in 2024** — Current, expert-reviewed public-health guidance with little commercial incentive, though it may not evaluate standing desks specifically or present primary evidence.  
3. **(d) 2015 trial with 24 office workers** — Direct experimental evidence, but the very small…

Task by task

Task	GPT-5.5	GPT-5.6 Sol
Make it answerable	10	10
Rank the sources	9	10
Synthesise the disagreement	9	9
Tear down the survey	10	9
Correlation for the neighbour	9	10
Plan the dig	9	10
What you cannot cite	10	10
Structure the evidence	10	10
Ask without leading	10	10
Two sources, head on	10	9
Primary or secondary	10	10
Refuse the invented bibliography	10	10

Full receipts: GPT-5.5, GPT-5.6 Sol · judges claude-sonnet-5, gemini-3.1-pro-preview, grok-4.5

Questions people ask

Which is better for research skills: GPT-5.5 or GPT-5.6 Sol?

Effectively a dead heat: GPT-5.6 Sol edged it 98/100 to 97/100 on our research skills suite — too close to matter, so pick on price or the product you already use.

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 · GPT-5.6 Luna vs GPT-5.6 Sol · GPT-5.3-Codex vs GPT-5.6 Sol · GPT-5.6 Sol vs GPT-5.6 Terra · GPT-5.6 Sol vs Grok 4.5

Full ranking: Best AI for research skills · model pages: GPT-5.5, GPT-5.6 Sol