  Deep learning models are widely used in critical applications, highlighting
the need for pre-deployment model understanding and improvement. Visual
concept-based methods, while increasingly used for this purpose, face
challenges: (1) most concepts lack interpretability, (2) existing methods
require model knowledge, often unavailable at run time. Additionally, (3) there
lacks a no-code method for post-understanding model improvement. Addressing
these, we present InterVLS. The system facilitates model understanding by
discovering text-aligned concepts, measuring their influence with
model-agnostic linear surrogates. Employing visual analytics, InterVLS offers
concept-based explanations and performance insights. It enables users to adjust
concept influences to update a model, facilitating no-code model improvement.
We evaluate InterVLS in a user study, illustrating its functionality with two
scenarios. Results indicates that InterVLS is effective to help users identify
influential concepts to a model, gain insights and adjust concept influence to
improve the model. We conclude with a discussion based on our study results.
