This paper constructs a theory according to which an intention is not a mental state but an action at a certain developmental stage. I model intention on organic life, and thus intention stands to action as (e.g.) tadpole stands to frog. I then argue for this theory by showing how it overcomes three problems: intending while (1) merely preparing, (2) not taking any steps, and (3) the action is impossible. The problems vanish when we see that not all actions are mature. Just as some frogs (such as tadpoles) are immature frogs, some actions (such as intentions) are immature actions.

The present study was aimed at investigating the effect of acute levodopa administration on the performance of a group of individuals with Parkinson's disease (PD) on a time-based prospective memory task. Twenty PD patients and 15 healthy controls were administered a task that required executing three actions after 10 min had elapsed in three consecutive trials. Scores were computed for correct recall of the intention to perform the actions and for correct execution of the actions. PD participants were evaluated after a 12-hr drug wash-out in two conditions: (1) after levodopa administration (“on”); (2) without drug administration (“off”). In the “on” condition, PD patients were significantly more accurate in retrieving the intention to perform the actions than in the “off” condition and their performance was actually comparable to that of healthy controls. The increased accuracy in complying with the prospective memory task following levodopa medication supports the idea that dopamine depletion plays a role in the prospective memory deficits observed in PD patients. (JINS, 2008, 14, 601–610.)