Extra-laboratorial usability tests: An empirical comparison of remote and classical field testing with lab testing.

The present article examined the effects of using different extra-laboratorial testing procedures in usability testing. Three experiments were conducted using different artefacts (website, computer-simulated mobile phone, fully operational smartphone) to compare different methodological approaches in field testing (synchronous and asynchronous remote testing, classical field testing) to lab-based testing under different operational conditions (dual task demands, poor product usability). Typical outcome variables of usability testing were measured, including task completion time, click rate, perceived usability and workload. Overall, the results showed no differences between field and lab-based testing under favourable operational conditions. However, under difficult operational conditions (i.e. dual task demands, poor product usability) differences between field and lab-based testing emerged (corresponding to small and medium effect sizes). The findings showed a complex pattern of effects, suggesting that there was no general advantage of one testing procedure over another.

The influence of product aesthetics and usability over the course of time: a longitudinal field experiment.

A longitudinal field experiment was carried out over a period of 2 weeks to examine the influence of product aesthetics and inherent product usability. A 2 × 2 × 3 mixed design was used in the study, with product aesthetics (high/low) and usability (high/low) being manipulated as between-subjects variables and exposure time as a repeated-measures variable (three levels). A sample of 60 mobile phone users was tested during a multiple-session usability test. A range of outcome variables was measured, including performance, perceived usability, perceived aesthetics and emotion. A major finding was that the positive effect of an aesthetically appealing product on perceived usability, reported in many previous studies, began to wane with increasing exposure time. The data provided similar evidence for emotion, which also showed changes as a function of exposure time. The study has methodological implications for the future design of usability tests, notably suggesting the need for longitudinal approaches in usability research. PRACTITIONER SUMMARY: This study indicates that product aesthetics influences perceived usability considerably in one-off usability tests but this influence wanes over time. When completing a usability test it is therefore advisable to adopt a longitudinal multiple-session approach to reduce the possibly undesirable influence of aesthetics on usability ratings.

Impact of physical and psychological resources on functional autonomy in old age.

Functional autonomy is a core condition of successful ageing. To maximize autonomous functioning is not only a claim of social policy but also primarily an individual need. Part of the challenge of preventing unnecessary dependence in old age is to recognize the diversity among the elderly and the different availability of their physical, psychological and social resources. The aim of this study is to examine the age- and time-related changes in functional autonomy (activities of daily living, ADL, and instrumental activities of daily living, IADL) and the psychophysical resources correlated with these changes in a sample of 441 healthy elderly persons aged 65-95. Furthermore, we are interested in the long-term predictive power of physical resources (objective and subjective health, physical strength) and psychological resources (memory) on functional autonomy. Results show significant age- and time-related deteriorations in functional autonomy and in most psychophysical resources. Structural equation model analyses were performed to test the long-term predictive power of these resources. Results suggest that ADL is better predicted by physical resources than by psychological ones, but for IADL the reverse is the case; here memory variables play a dominant role. Physical and psychological variables are thus specifically related to different components of functional autonomy. This has to be taken into account in the development of preventive and intervention programmes.