Evaluating Cognitive Complexity of Algebraic Equations

While blind and visually impaired (BVI) readers can access digital text information using auditory interface through screen readers, accessing mathematical equations is much more challenging task, which is known to limit access to STEM subjects for BVI students. This is primarily due to the complexities of equation layout as well as the fact that only a small number of symbols can lead to a very lengthy speech string resulting in a high cognitive load for the reader. One approach to reduce this load can be to abstract parts of an equation/expression via some abbreviating symbol which is then read out separately. This division/partitioning into expressions is based on computing the cognitive complexity as "felt" by the reader. In this paper we present a study that aims to identify a suitable metric for this cognitive complexity. To assess this complexity, we have conducted an extensive user study with eighteen VI persons. In our study we captured users' response in terms of errors in reproducing equations, time taken to understand an equation, etc. We used this data to propose candidate metrics for measuring this complexity. We correlated these metrics with complexity measures available in open-source systems for math accessibility. We have been able to identify a suitable complexity metric that correlates well with results obtained from user study and thus can be integrated to screen readers while accessing equations.