Computer-implemented method for determining a threshold regarding an aging adult's ability to remember and perform sequences of auditory instructions. A stage specifies a set of stimulus attributes. First and second tracks are respectively initialized to stage values below and above an initial anticipated threshold specifying an initial estimate of stimulus attributes corresponding to a specified performance level of the adult. A sequence of auditory instructions is presented indicating respective manipulations of graphical objects in accordance with the stage value of a specified one of either the first or second track. Input manipulating the graphical objects is received from the adult, and the stage value of the track modified in response. This is performed with respect to each of a plurality of sequences to determine final stage values for the tracks, and a threshold comprising the stage value associated with the specified performance level determined based on the final stage values.