As many psychologists have suggested, evoking memories of gratitude and then writing them down is recognized as an efficient daily activity to improve people's subjective happiness and well-being. This paper studies how using a smart voice agent, such as a smartphone and smart speaker, affects this activity. Instead of traditional handwriting, expressing gratitude through the voice agent has several benefits in terms of human-computer interaction aspects. As a first step for this study, we conducted short-term experiments using a voice agent with Japanese university students, including native Japanese and foreigners, and evaluated changes in their emotional state by using two psychological measurements, the Positive and Negative Affect Schedule (PANAS) and the Subjective Happiness Scale (SHS). The evaluation results revealed three important findings: (1) expressing and receiving gratitude via voice agent can potentially enhance positive affect and subjective happiness similar to traditional handwriting, (2) generating natural gratitude messages (e.g., from close friends or family) significantly improves positive affect and happiness, and (3) some people experience stress over tasks or methods of expressing gratitude, decreasing positive affect.

The purpose of this research is to encourage consideration of gift-receivers in the gift selection process from various perspectives. People often purchase gifts for their loved ones, such as partners and friends. There are various e-commerce websites that recommend gifts for loved ones; however, selecting an appropriate gift is difficult because these recommendations do not consider gift-receivers' hobbies and preferences. Entering all their hobbies and preferences into the system in advance will solve this problem, but it takes time and effort. To solve this problem, we proposed a system that encourages consideration of gift-receivers by themselves. To achieve this, the proposed system provides questions about the gift-receiver and facilitates deeper consideration in gift selection. Using this proposed system, we conducted an experiment to observe the participants' gift selection process. As a result, we confirmed that the system increases people's consideration of gift-receivers.