Using eye tracking for evaluation of information visualisation in web search interfaces

Search result organization and presentation is an important component of a web search system, and can have a substantial impact on the ability of users to find useful information. Most web search result interfaces include textual information, including for example the document title, URL, and a short query-biased summary of the content. Recent studies have developed various novel visual summaries, aiming to improve the effectiveness of search results. In this thesis, the impact and efficacy of presenting additional visual summaries are investigated through a series of four studies. User interaction with the search results was captured using eye tracking data. In the first study we compare the effectiveness of three publicly available search interfaces for supporting navigational search tasks. The three interfaces varied primarily in the proportion of visual versus textual cues that were used to display a search result. Our analysis shows that users' search completion time varies greatly among interfaces, and an appropriate combination of textual and visual information leads to the shortest search completion time and the least number of wrong answers. Another outcome of this experiment is the identification of factors that should be accounted for in subsequent, more controlled, experiments with visual summaries, including the size of the visual summaries and interface design. An understanding of the features and limitations of the eye tracker, particularly for IR studies, was also obtained. To obtain a richer understanding of a user's information seeking strategies and the impact of presenting additional visual summaries, five interfaces were designed: text-only, thumbnail, image, tag and visual snippet. In the second study, fifty participants carried out searches on five informational topics, using the five different interfaces. Findings show that visual summaries significantly impact on the behaviour of users, but not on their performance when predicting the relevance of answer resources. In the third study, fifty participants carried out five navigational topics using the five different interfaces. The results show that apart from the salient image interface, users perform statistically significantly better in terms of time required and effort required to answer given navigational search topics when additional visual summaries are presented. The fourth study was conducted with both navigational and informational topics, for a more detailed comparison between the best-performing interfaces identified in the previous studies: salient images for informational searches, and thumbnails for navigational searches. The findings confirm our previous results. Overall, the salient image interface can significantly increase user performance with informational topics, while thumbnails can help users to predict relevant answers, in a significantly shorter time, with navigational search topics

Identification of web usability problems and interaction patterns with the RealEYES-iAnalyzer

The focus of our paper is on managing and representing the huge amount of performance data coming from quantitative usability studies which are considered an important source needed to specify usability problems. The developed RealEYES-iAnalyzer is a tool which supports the evaluator of an interactive system by automatic data-processing and provides an expressive and effective data-playback. We carried out an empirical study with 36 test participants using the RealEYES-iAnalyzer during a web-browsing session. The measurement results show different patterns of mouse-/gaze behaviour and allowed us to draw hypotheses about the phenomenology of interaction problems