An association between spatial ability, particularly visualisation, and science, technology, engineering, and mathematics (STEM) education has been repeatedly demonstrated over the past four decades. Understanding this relationship is of critical importance as substantial evidence illustrates the malleability of spatial ability and that the effects of associated training interventions transfer to desirable STEM outcomes such as improved educational performance and reduced attrition rates. There currently exists a number of theories as to why spatial ability relates to STEM, such as that the nature of STEM activity is inherently spatial. However, there is a need to better understand this relationship from a cognitive perspective. This research examined the hypothesis that spatial ability is predictive of short-term retention for declarative technical information associated with engineering curricula. An original investigation in an authentic educational setting found that visualisation and interest in the lecture material were significant predictors of short-term knowledge retention. This effect was then replicated in two subsequent conceptual replication studies. Based on this predictive finding, it is theorised that increases in spatial ability may support the elongation of the knowledge forgetting curve which would have significant implications for instructional design.