It’s worth noting that there’s reasons to expect the “base models” of both Gemma2 and Qwen 1.5 to demonstrate refusals—neither is trained on unfilted webtext.
We don’t know what 1.5 was trained on, but we do know that Qwen2′s pretraining data both contains synthetic data generated by Qwen1.5, and was filtered using Qwen1.5 models. Notably, its pretraining data explicitly includes “high-quality multi-task instruction data”! From the Qwen2 report:
Quality Enhancement The filtering algorithm has been refined with additional heuristic and modelbased methods, including the use of the Qwen models to filter out low-quality data. Moreover, these models are utilized to synthesize high-quality pre-training data. (Page 5) [...] Similar to previous Qwen models, high-quality multi-task instruction data is integrated into the Qwen2 pre-training process to enhance in-context learning and instruction-following abilities.
I think this had a huge effect on Qwen2: Qwen2 is able to reliably follow both the Qwen1.5 chat template (as you note) as well as the “User: {Prompt}\n\nAssistant: ” template. This is also reflected in their high standardized benchmark scores—the “base” models do comparably to the instruction finetuned ones! In other words, Qwen2 “base” models are pretty far from traditional base models a la GPT-2 or Pythia as a result of explicit choices made when generating their pretraining data and this explains its propensity for refusals. I wouldn’t be surprised if the same were true of the 1.5 models.
I think the Gemma 2 base models were not trained on synthetic data from larger models but its pretraining dataset was also filtered to remove “unwanted or unsafe utterances”. From the Gemma 2 tech report:
We use the same data filtering techniques as Gemma 1. Specifically, we filter the pretraining dataset to reduce the risk of unwanted or unsafe utterances, filter out certain personal information or other sensitive data, decontaminate evaluation sets from our pre-training data mixture, and reduce the risk of recitation by minimizing the proliferation of sensitive outputs. (Page 3) [...] We undertook considerable safety filtering of our pre-training data to reduce the likelihood of our pre-trained and fine-tuned checkpoints producing harmful content. (page 10)
My guess is this filtering explains why the model refuses, moreso than (and in addition to?) ChatGPT contamination. Once you remove all the “unsafe completions”
I don’t know what’s going on with LLaMA 1, though.
After thinking about it more, I think the LLaMA 1 refusals strongly suggest that this is an artefact of training data.So I’ve unendorsed the comment above.
It’s still worth noting that modern models generally have filtered pre-training datasets (if not wholely synthetic or explicitly instruction following datasets), and it’s plausible to me that this (on top of ChatGPT contamination) is a large part of why we see much better instruction following/more eloquent refusals in modern base models.
It’s worth noting that there’s reasons to expect the “base models” of both Gemma2 and Qwen 1.5 to demonstrate refusals—neither is trained on unfilted webtext.
We don’t know what 1.5 was trained on, but we do know that Qwen2′s pretraining data both contains synthetic data generated by Qwen1.5, and was filtered using Qwen1.5 models. Notably, its pretraining data explicitly includes “high-quality multi-task instruction data”! From the Qwen2 report:
I think this had a huge effect on Qwen2: Qwen2 is able to reliably follow both the Qwen1.5 chat template (as you note) as well as the “User: {Prompt}\n\nAssistant: ” template. This is also reflected in their high standardized benchmark scores—the “base” models do comparably to the instruction finetuned ones! In other words, Qwen2 “base” models are pretty far from traditional base models a la GPT-2 or Pythia as a result of explicit choices made when generating their pretraining data and this explains its propensity for refusals. I wouldn’t be surprised if the same were true of the 1.5 models.
I think the Gemma 2 base models were not trained on synthetic data from larger models but its pretraining dataset was also filtered to remove “unwanted or unsafe utterances”. From the Gemma 2 tech report:
My guess is this filtering explains why the model refuses, moreso than (and in addition to?) ChatGPT contamination. Once you remove all the “unsafe completions”
I don’t know what’s going on with LLaMA 1, though.
After thinking about it more, I think the LLaMA 1 refusals strongly suggest that this is an artefact of training data.So I’ve unendorsed the comment above.
It’s still worth noting that modern models generally have filtered pre-training datasets (if not wholely synthetic or explicitly instruction following datasets), and it’s plausible to me that this (on top of ChatGPT contamination) is a large part of why we see much better instruction following/more eloquent refusals in modern base models.