I must say that I found the title of this book a bit misleading. I expected emotion to play a more prominent role in its contents, and I was a bit disappointed to discover that it is instead a secondary actor in a doctoral dissertation whose objective is to investigate the effects of providing feedback messages about the system’s state, in mobile applications, using different modalities. Auditory, tactile, and auditory-tactile modality variations are explored.
The affective impression of the messages is evaluated as well as their functional adequacy, which is their effectiveness in conveying appropriate information. Also, the influence of context on feedback perception was evaluated, under three different context conditions (a bar, an office, and neutral). As a result, four general guidelines for the design of feedback messages are provided in chapter 9, which also includes a summary of the main conclusions that were reached. This chapter is of interest for interaction designers, while the complete book is mainly targeted toward researchers in human-computer interaction.
The research process and findings are presented in detail in one chapter devoted to auditory feedback, another one for tactile feedback, and a third one for audio-tactile combinations.
As a first step in the research, some focus groups were conducted to identify appropriate sounds that could be used as auditory icons for a list of six prototypical events that can occur during interaction with a mobile device. Then, an association study was conducted to find out how those sounds were in fact interpreted by users (their affective impression), by using the self-assessment manikin (SAM). This led to the selection of 11 auditory icons to be used, together with 10 earcons, in a context study following a within-subjects design, where users rated the affective impression of each sound using an adapted SAM and functional adequacy (for each of the six events) in a -2 to 2 scale.
A similar research process was followed for the identification of vibrotactile messages or tactons that were distinguishable and possibly meaningful, via a pilot study, resulting in 16 tactons that were used in the subsequent context study. In addition to affective impression and functional adequacy, the subjective mental effort under each context was rated by the participants for tactile feedback.
In a third stage, 27 combinations of sounds and vibrations were produced, according to their SAM ratings, adequacy for a certain function, and timely structure and duration. Both congruent and inconsistent pairs were generated. These combinations were again rated by participants in a new context study. A strong influence of the sound component on the combined audio-tactile perception was noticed.
A final interaction study was carried out in which participants had to interact with a very simple mobile application, receiving different types of feedback messages for different events. This was a more realistic and complex evaluation that allowed for the study of the effects of modality types on user performance and the relation between user ratings and performance, and also permitted comparisons between different modality combinations.
The research presented sheds some light on the complex interplay between modality types and different event feedback types, and also shows that rating the perception of a stimulus in isolation can be insufficient to predict its affective impression and adequacy while interacting with an application in a real situation.
