The Physics of Notations (PoN) is a framework to design
cognitively effective notations. The term cognitive effectiveness here
refers to the ease (speed and accuracy) by which model readers read the
models. In 2019 a PoN-Enabled notation for use case diagrams was
proposed. It has been empirically proven that the cognitive
effectiveness of this new notation is superior to the original use case
notation. The new notation however relies in part on the use of color.
The accessibility of this new design however has not been validated for
use by the color-blind community, or any users who need to use a
greyscale version of the models created. The PoN framework was not
designed to explicitly account for the color-blind community or users
who can only access greyscale versions of the models. Inclusivity should
not be an afterthought in software engineering practice or research. To
this end, this paper presents an empirical evaluation of the cognitive
effectiveness of the PoN-enabled use case notation in the situation it
was viewed in greyscale.