Technological advancements provide people with more opportunity to rely on external resources to support cognitive processes. These associated processes are defined as cognitive offloading (Risko & Gilbert, 2016). The current thesis aims to explore the psychological processes and neural mechanism of cognitive offloading. In Experiment 1, we developed an ‘optimal reminder’ task by calculating whether people were biased towards using reminders or their own memory, compared with an optimal strategy. If participants were biased, the second purpose of Experiment 1 was to assess whether such bias could be reduced through metacognitive advice. Results revealed people were biased towards setting reminders, and the bias was eliminated by metacognitive advice. Experiment 2 used the optimal reminder task to evaluate the effect of ageing on cognitive offloading. This showed that older people set more reminders than younger adults, but were less biased towards setting reminders when the impaired memory performance of older people was taken into account. Experiment 3 investigated the effects of three factors: delay length, metacognitive judgement, and clock revealability, on cognitive offloading in a time-based task (e.g. remembering to press a specific button after 10 seconds). We found participants’ use of reminders was based on both the characteristics of the task (i.e., delay and clock revealability) and metacognitive judgements. Experiment 4 used fMRI to evaluate whether an instruction to offload information to an external reminder triggered different brain activity to an instruction to forget or remember. Results showed that brain activity associated with an offload cue was similar, but not identical, to brain activity associated with a forget cue. We conclude by suggesting possible applications of the results to finding methods for improving intention offloading and avoiding memory failures.