The invention relates to a task planning system and method for use in cognitive ability-related treatment. The inventive system comprises: at least one central control and processing unit (B1) which manages a database of users and definitions of exercises and methods for cognitive ability-related treatment; at least one client computer (A1) for the user performing exercises; and communication means between the central control and processing unit (B1) and the user client computer, which are designed to (i) send exercises from the central control and processing unit (B1) to the user client computer (A1) that are proposed by decision-making means and (ii) send the results of the exercises from the user client computer (A1) to the central control and processing unit (B1). The aforementioned decision-making means comprise an expert system (B2) which is implemented in the central control and processing unit (B1) and which is designed to determine automatically the exercises to be performed by the user in a personalised manner, such that they are adapted to the user's development.