JMIR Publications

ABSTRACT

Background:

In affective exergames, game difficulty is dynamically adjusted to match the user’s physical and psychological state, thus providing an appropriate user experience. Such adjustment is commonly done based on a combination of performance measures (e.g., in-game scores) and physiological measurements, which provide insight into the player’s psychological state. However, while many prototypes of affective games have been presented and many studies have shown that physiological measurements allow more accurate classification of the player’s psychological state than performance measures, relatively few studies have examined whether dynamic difficulty adjustment (DDA) based on physiological measurements (which requires additional sensors) actually results in a better user experience than simple performance-based DDA or manual difficulty adjustment.

Objective:

The objective of this study is to compare five DDA methods in an affective exergame: manual (player-controlled), random, performance-based (PE), personality-performance-based (PEPE), and physiology-personality-performance-based (All-Data).

Methods:

Fifty participants were divided into five groups corresponding to the five DDA methods. They played an exergame version of Pong for 18 minutes, starting at a medium difficulty; every 2 minutes, two game difficulty parameters (ball speed and paddle size) were adjusted using the participant’s assigned DDA method. The DDA rules for the PE, PEPE and All-Data groups were developed based on data from a previous open-loop study. Seven physiological responses were recorded throughout the sessions, and participants self-reported their preferred changes to difficulty every 2 minutes as well. After playing the game, participants reported their in-game experience using two questionnaires: the Intrinsic Motivation Inventory and the Flow Experience Measure.

Results:

The ‘All-Data’ method induced the highest enjoyment, competence, pressure, and flow – even higher than the manual method. However, the differences in enjoyment and flow were not significant. Furthermore, the accuracy of changes to ball speed (defined as the percentage match between DDA choice and participants’ preference) was significantly correlated with the players’ enjoyment (r = 0.38) and pressure (r = 0.43).

Conclusions:

Personality and physiological responses appear to be worth including in affective exergames since they do result in higher classification accuracies and a more positive user experience. While the obtained results cannot be fully generalized to longer-term exercise or other serious games, they add to the limited body of evidence about the relative benefits of physiological measurements in exergames and affective computing.