Scientific Background
The attractiveness of a product is becoming increasingly important in usability investigations. Until recently evaluation methods were confined to the essential usability. Usability having meant pragmatic quality alone.
Today a method of evaluation is being sought whereby both the recognised pragmatic quality as well as the hedonic quality of an interactive product can be gauged.
A theoretical work model (Diagram 1) illustrates how the pragmatic and hedonic qualities influence subjective perceptions of attractiveness resulting in respective behavioural and emotional responses.
The model separates the four essential aspects:
- The product quality intended by the designer.
- The subjective perception of quality and subjective evaluation of quality.
- The independent pragmatic and hedonic qualities.
- Behavioural and emotional consequences.
Diagram1: The theoretical work model illustrates how the pragmatic and hedonic qualities influence the subjective perception of attractiveness giving rise to consequent behaviour and emotions. (© User Interface Design GmbH)
The theoretical work model was researched and tested in several studies by Hassenzahl and colleagues.
AttrakDiff-1 was applied as an instrument of measurement in the format of semantic differentials. It consists of 23 seven-step items whose poles are opposite adjectives (e.g. "confusing - clear", "unusual - ordinary", "good - bad"). Each set of adjective items is ordered into a scale of intensity. Each of the middle values of an item group creates a scale value for pragmatic quality (PQ) , hedonic Quality (HQ) and attractiveness (ATT).
The studies showed that the hedonic and pragmatic qualities are perceived consistently and independent of one another. Both contribute equally to the rating of attractiveness.
While testing and implementing AttrakDiff-1 it became clear that a separation of the two constituent aspects of hedonic quality, namely stimulation and identity would be preferable.
Hence AttrakDiff was developed. AttrakDiff optimises and supports the distinction between the sub-qualities, stimulation and identity, of hedonic quality. (see also Publications)