In an Experience Sampling Method (ESM) based emotion self-report collection study, engaging participants for a long period is challenging due to the repetitiveness of answering self-report probes. This often impacts the selfreport collection as participants dropout in between or respond with arbitrary responses. Self-reflection (or commonly known as analyzing past activities to operate more efficiently in the future) has been effectively used to engage participants in logging physical,

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... l, or psychological data for Quantified Self (QS) studies. This motivates us to apply self-reflection to improve the emotion self-report collection procedure. We design, develop, and deploy a self-reflection interface and augment it with a smartphone keyboard-based emotion self-report collection application. The interface provides feedback to the users regarding the relation between typing behavior and self-reported emotions. We validate the proposed approach using a betweensubject study, where one group (control group) is not exposed to the self-reflection interface and the other group (study group) is exposed to it. Our initial results demonstrate that using self-reflection it is possible to engage the participants in the long-term and collect more self-reports.