Technological developments are impacting upon UK assessment practices in many ways. For qualification awarding bodies, a key example of such impact is the ongoing shift towards examiners marking digitally scanned copies of examination scripts on screen rather than the original paper documents. This digitisation process has obvious benefits, affording flexible information management and distribution. Digitisation can also lead readers to interact differently with texts, with readers' physical engagement with digital texts differing from traditional paper-based texts. More specifically, it appears that reader navigation and annotation behaviours are particularly influenced by a digital mode shift. A consequence of this is that it is possible that the mental workload involved in reading on screen is greater than when reading on paper. Moreover, it is theorised that this additional load can have an adverse affect on reader comprehension building. These findings prompt questions about whether the mode of marking might unduly influence marking outcomes when assessors read longer essay responses in a digital environment. In light of this concern, this article explores how marking mode influences examiner essay marking behaviours, which in turn might influence their comprehension building and their marking outcomes. This study gathers data from 12 experienced examiners working within a large UK-based awarding body to investigate how mode influences their navigation and annotation behaviours when marking extended essays on paper and on screen. These comparative data are then used to explore a model which suggests that manual marking behaviours, such as navigation and annotation, can influence examiners' comprehension whilst marking. The implications for future developments in digital essay-marking software are then discussed. (Contains 4 figures and 5 tables.)