The current study aims to investigate the effects of three key demographic factors -- the language of marking, gender and age -- on markers' reactions to onscreen marking (OSM). A total of 1743 markers completed a post-marking questionnaire consisting of two previously validated scales, i.e. "Ease of Use in the OSM Environment" and "Acceptance of OSM scales." Rasch analysis results showed that the two scales had good psychometric properties. Markers generally reported finding the system easy to use and positive acceptance of OSM. Markers marking in both English and Chinese had higher perceived ease of use and acceptance than markers who marked only in English or in Chinese. Gender also had a significant impact on markers' responses to the two scales -- favouring males. Age was not a significant factor influencing markers' perceived ease of use but older markers revealed a significantly higher level of acceptance than younger markers.