1. A memory for storing data for access by an application program being executed on a data processing system, comprising: a data structure stored in the memory, the data structure comprising information resident in a database used by the application program; the application program trains a machine learning based affective response model for a user, using the data structure stored in the memory; the data structure stored in the memory comprising: token instances representing stimuli that influence a user's affective state, stored in the memory; the stored token instances are spread over a long period of time that spans different situations, and a plurality of the stored token instances have overlapping instantiation periods; data representing levels of user attention in some of the token instances, used by the application program to improve the accuracy of the machine learning based affective response model for the user; annotations representing emotional states of the user, stored in the memory; the stored annotations are spread over a long period of time that spans different situations; and linkage information between the token instances, the data representing levels of user attention, and the annotations.