  In this paper, we introduce the Instruction Following Score (IFS), a metric
that detects language models' ability to follow instructions. The metric has a
dual purpose. First, IFS can be used to distinguish between base and instruct
models. We benchmark publicly available base and instruct models, and show that
the ratio of well formatted responses to partial and full sentences can be an
effective measure between those two model classes. Secondly, the metric can be
used as an early stopping criteria for instruct tuning. We compute IFS for
Supervised Fine-Tuning (SFT) of 7B and 13B LLaMA models, showing that models
learn to follow instructions relatively early in the training process, and the
further finetuning can result in changes in the underlying base model
semantics. As an example of semantics change we show the objectivity of model
predictions, as defined by an auxiliary metric ObjecQA. We show that in this
particular case, semantic changes are the steepest when the IFS tends to
plateau. We hope that decomposing instruct tuning into IFS and semantic factors
starts a new trend in better controllable instruct tuning and opens
possibilities for designing minimal instruct interfaces querying foundation
models.
