Cognitive offloading refers to the use of physical actions to alter the information processing requirements of a task so as to reduce cognitive demand. The present thesis aims to broaden research on cognitive offloading by investigating this phenomenon in the previously unexplored cognitive domain of route planning. The studies presented in this thesis also seek to deepen our understanding of the consequences of cognitive offloading on task performance. Cognitive offloading has been extensively investigated in relation to perception, short-term memory, and delayed intentions. In these domains, cognitive offloading has been consistently found to improve task performance in terms of accuracy and/or speed. However, even in the absence of performance advantages, individuals tend to rely on cognitive offloading after its initial use. Among the predictors of cognitive offloading explored so far, higher cognitive load associated with the task, lower cognitive abilities, reduced metacognitive confidence in unaided performance, and the avoidance of cognitive effort, appear to play a significant role in determining the use of cognitive offloading over internal resources. Despite providing important insights, research in this area has generally employed relatively simple tasks predominantly focused on memory-related and perceptual domains, leaving cognitive offloading in more complex tasks and domains largely unexplored. Study 1 aimed to address this gap by investigating cognitive offloading in the context of a complex spatial planning task. Specifically, the study examined which offloading strategies were spontaneously devised by individuals while planning routes on maps, as well as the generalizability of findings from previous research on cognitive offloading to this task. In particular, Study 1 explored whether using offloading strategies improved route planning performance, whether greater task difficulty led to a greater reliance on these strategies, and whether they continued to be used even in the absence of performance advantages. The study also investigated the relationship between offloading strategy use and individual differences in cognitive abilities relevant to the task, as well as participants' subjective perceptions of task difficulty and effort. Building on findings from Study 1, Studies 2 and 3 aimed to extend the understanding of the consequences of cognitive offloading on subsequent task performance. While previous research on cognitive offloading has primarily focused on the impact of external aids (e.g., the Internet, digital storage) on episodic memory, less is known about how engaging in cognitive offloading influences future performance on the same task. Studies 2 and 3 sought to address this gap by investigating what occurs when the opportunity to offload cognition is removed or introduced in a subsequent stage of a route planning task. Both studies hypothesized asymmetric transfer effects, predicting a greater decline in performance following the removal of offloading opportunities than the improvement observed when offloading was introduced, due to asymmetric effects of shifts in planning strategies. Similar to Study 1, Study 2 focused on offloading strategies spontaneously devised by participants, while Study 3 employed external visual aids to support the cognitive offloading strategies identified in the first two studies. Finally, Study 4 investigated whether the findings from the previous studies could be replicated when using more ecological materials. Specifically, the study assessed whether the external aids employed in Study 3 on fictitious maps for supporting the identified offloading strategies remained effective in supporting route planning when embedded in a real-world map.