Naturally, the mood repertoire is far more nuanced than the basic good-bad distinction would have us believe: an individual can experience a range of moods that are perceived as good (e.g., cheerful, relaxed, elated) or bad (e.g., gloomy, grumpy, nervous). So far, we have not explicitly described moods. The analysis was mostly based on the functional view on mood developed by Morris (1992, 1998, 1999, 2000), complemented with insights from the work on the nature of the mood phenomenon (e.g., Lazarus, 1991 Parkinson, Totterdell, Briner, & Reynolds, 1996), the strategies that people employ to influence their own moods (e.g., Gross, 2007 Larsen, 2000), and techniques to regulate mood (e.g., Martin, 1990 Schneider, Gur, Gur, & Muenz, 1994). To this end, four basic questions are addressed: how can mood be described? what is the function of mood? what are the manifestations of mood? and how does mood differ from emotion? The approach of this analysis was pragmatic: reviewing theory available in psychology and philosophy, and collecting those insights that enable a functional analysis of human mood in the context of design interventions.

The second part of the paper provides a functional explanation of the mood phenomenon. One can be sad or cheerful for several hours, or even for several days (Beedie, Terry & Lane, 2005). Although limited in time, moods tend to have a relatively long-term character.

Consequently, we are usually unable to specify the cause of a particular mood (Ekman, 1994). Where emotions are usually elicited by an explicit cause (e.g., some event), moods have diffuse or combined causes. In other words, moods represent positive and negative frames of mind that subtly influence our responses to all the events we encounter: when ‘in a mood’, a person sees the world – and everything in it – as dim and grey, while when cheerful, the same person sees the world through rose-coloured glasses. This means that one’s mood is not directed at anyone or anything in particular, but rather at the surroundings in general, or, in the words of Frijda (1994), at “the world as a whole” (p. Unlike emotions, moods are not directed toward specific targets, but instead have a broad influence on one’s perceptions, judgments, and behaviour (Kelley & Hoffman, 1997 Martin & Clore, 2013). Mood is a diffuse and general feeling state that provides the affective colouring for all day-to-day events (Morris, 1989). Because these three consequences hinder the progression of the field, the next two parts of the manuscript introduce a basic mood theory and a set of theory-based design opportunities.

Thirdly, the lack of precision has created conceptual confusion by enabling design researchers to overlook important differences between causes and manifestations of emotions and moods. Secondly, not all of the explored strategies may be effective because many of the underlying intuitive assumptions have been shown to be unreliable (see introduction for an overview). Firstly, by building on intuitive assumptions about the causes of mood, only a limited repertoire of strategies to influence mood has been explored. This limited theoretical substantiation has several unwanted consequences. Most of the reviewed work that explored the mood-influencing possibilities of design does not report underlying hypotheses surrounding the kind of design features or qualities that might affect mood in a particular way. Usage can be initiated by the user (i.e., the user wants to regulate his or her mood) or by some other party (i.e., the user may not be aware that mood-influencing technology has been introduced). that does not rely on mood measurement, like Paro or the Adaptive Relaxation Space shown in Figure 1.

Types of moods and affects