Abstract: A computing device for logging changes in a person's mood over time, the device comprising a user interface for receiving a user-input selecting one of a plurality of mood descriptors indicative of the user's mood at a current point in time, a processor configured to determine a pair of values associated with the selected mood descriptor, wherein a first value in the pair of values defines a position on a first mood axis and the second value in the pair defines a position on a second mood axis, the first and second mood axes being associated with different aspects of mood, a memory for storing the pair of values together with an indicator of the current point in time, the processor being further configured to compare the pair of values with one or more other pairs of values obtained at respective points in time, thereby to generate trend date reflecting one or more trends in the values over time.