Tunnereaktiot tuntopalautteeseen

Erilaisia tuntopalautteita käytetään nykyään enenevissä määrin eri sovelluksissa. Esimerkiksi kännykät, tabletit ja peliohjaimet antavat usein palautetta tuntoaistin avulla käyttäjälleen. Yleisesti tällä hetkellä laitteissa käytetään värinäpalautetta, mutta tuntopalautetta on mahdollista tuottaa myös esimerkiksi lämmön tai kitkan avulla.
Aiempien tutkimusten perusteella tiedetään, että tuntopalaute parantaa ihmisten suoritusta esimerkiksi kosketusnäytön näppäimistöllä kirjotettaessa.

Tuntopalautteiden vaikutusta ihmisen tunnejärjestelmään on sen sijaan tutkittu verrattain vähän. Useimmat aiemmat tutkimukset liittyvät ihmisten väliseen kommunikaatioon tai prototyyppien toimivuuteen.
Tällaiset tutkimukset eivät vastaa kysymykseen siitä, millä tapaa tuotetut palautteet ovat esimerkiksi mahdollisimman miellyttäviä tai herättävät käyttäjän huomion tehokkaasti.

Väitöskirjassa vertaillaan miten eri tavoin tuotetut tuntopalautteet voivat vaikuttaa ihmisen tunnejärjestelmän toimintaan kuuden kokeen sarjassa. Tutkimuksissa on hyödynnetty mittausmenetelmiä psykologian saralla kehitetyistä tunneteorioista. Kokeissa osallistujat ovat esimerkiksi arvioineet erilaisia tuntopalautteita samalla, kun autonomisen hermoston aktivoitumista on mitattu.

Väitöskirjan tulokset osoittavat, että tuntopalautteen avulla on mahdollista herättää ihmisissä erilaisia tunnekokemuksia. Lämmön ja kitkan avulla tuotetut palautteet näyttäisivät toimivan värinää paremmin tässä tarkoituksessa.

The present aim was to experimentally investigate how different types of haptic stimulations are associated with the human emotion system. Prototype technologies were built to create computer driven friction-based, vibrotactile, and thermal sensations. Haptic technologies (i.e., friction-based, vibrotactile, and thermal), stimulus parameters (e.g., amplitude and continuity), and modality (i.e., haptic only or haptic auditory) were varied in the studies. Responses were measured using emotion-related rating scales (i.e., valence, approachability, arousal, and dominance), behavioral measurements, and changes in skin conductance response (i.e., SCR) reflecting the level of physiological arousal.

The results showed that different haptic stimulations activated the human emotion system differently, as evidenced by subjective ratings and behavioral and physiological changes. The vibrotactile stimuli were connected to the level of arousal and dominance so that, for instance, stimuli with high amplitudes were rated as more arousing and dominant than stimuli with low amplitudes. However, on the scales of pleasantness and approachability vibrotactile stimuli were in general rated as neutral despite the parametrical variation. Friction-based and thermal stimuli effected the ratings on all of the four scales. Continuous stimuli and high intensity stimuli were rated as less pleasant, less approachable, more arousing, and more dominant than discontinuous and low intensity stimuli. Thus, friction-based and thermal stimuli resulted in a wider variation in respect of the emotion-related ratings than vibrotactile stimuli.

Variation of the modality affected the ratings of vibrotactile stimuli in somewhat different manner. The ratings of arousal and dominance were affected so that the vibrotactile-auditory stimuli were always rated as more arousing and dominant than auditory only stimuli. Interestingly, when the modality was varied also the ratings of pleasantness were affected. When the vibrotactile stimulus was congruent with the auditory signal, the stimulus was rated as less pleasant than when the stimulus was auditory only.

The results of SCR and behavioral measurements supported the findings of the subjective ratings. SCR was higher in magnitude when the stimulus was rated as arousing than when it was rated as calm. The stimuli rated as arousing were also differentiated faster and more accurately than the stimuli rated as calming.

In summary, the current thesis demonstrated that different computer driven haptic stimulations activated the human emotion system differently, as evidenced by subjective ratings and behavioral and physiological responses. Particularly in respect of the ratings along the four emotion related dimensions, it can be concluded that friction and thermal stimulations were better at evoking changes in the ratings of pleasantness and approachability than vibrotactile stimuli. Vibrotactile stimuli were associated with a higher level of arousal and a feeling of being controlled by the stimulation. As there is growing interest in using stimulation of the sense of touch in human-technology interaction, it is likely that the results of the current thesis can be utilized in designing haptics-based affective computing.