Kari-Jouko Räihä

Twenty years of eye typing: systems and design issues

Eye typing provides a means of communication for severely handicapped people, even those who are only capable of moving their eyes. This paper considers the features, functionality and methods used in the eye typing systems developed in the last twenty years. Primary concerned with text production, the paper also addresses other communication related issues, among them customization and voice output.

Design by exmple: An application of Armstrong relations

Abstract Example relations, and especially Armstrong relations, can be used as user friendly representations of dependency sets. In this paper we analyze the use of Armstrong relations in database design with functional dependencies, and show how they and the usual representation of dependencies can be used together. Special attention is given to the size of Armstrong relations. We derive new bounds for the size of minimal Armstrong relations for normalized schemes. Specifically, any relation scheme in Boyce-Codd Normal Form has an Armstrong relation whose size is roughly the product of the lenghts of the keys for the scheme. New algorithms are also given for generating Armstrong relations and for inferring the functional dependencies holding in a relation.

Eye-tracking reveals the personal styles for search result evaluation

We used eye-tracking to study 28 users when they evaluated result lists produced by web search engines. Based on their different evaluation styles, the users were divided into economic and exhaustive evaluators. Economic evaluators made their decision about the next action (e.g., query re-formulation, following a link) faster and based on less information than exhaustive evaluators. The economic evaluation style was especially beneficial when most of the results in the result page were relevant. In these tasks, the task times were significantly shorter for economic than for exhaustive evaluators. The results suggested that economic evaluators were more experienced with computers than exhaustive evaluators. Thus, the result evaluation style seems to evolve towards a more economic style as the users gain more experience.

The shortest common supersequence problem over binary alphabet is NP-complete

Abstract We consider the complexity of the Shortest Common Supersequence (SCS) problem, i.e. the problem of finding for finite strings S 1 , S 2 ,…, S u a shortest string S such that every S i can be obtained by deleting zero or more elements from S . The SCS problem is shown to be NP-complete for strings over an alphabet of size ⩾ 2.

Discovering functional and inclusion dependencies in relational databases

We consider the problem of discovering the functional and inclusion dependencies that a given database instance satisfies. This technique is used in a database design tool that uses example databases to give feedback to the designer. If the examples show deficiencies in the design, the designer can directly modify the examples. the tool then infers new dependencies and the database schema can be modified, if necessary. the discovery of the functional and inclusion dependencies can also be used in analyzing an existing database. the problem of inferring functional dependencies has several connections to other topics in knowledge discovery and machine learning. In this article we discuss the use of examples in the design of databases, and give an overview of the complexity results and algorithms that have been developed for this problem.

101 spots, or how do users read menus?

In modern graphical user interfaces pull-down menus are one of the most frequently used components. But still after years of research there is no clear evidence on how the users carry out the visual search process in pull-down menus. Several models have been proposed for predicting selection times. However, most observations are based only on execution times and cannot therefore explain where the time is spent. The few models that are based on eye movement research are conflicting. In this study we present an experiment where eye movement data was gathered in a menu usage task. By analyzing the scan paths of the eye, we found that menus are read in sequential sweeps. This may explain why the best models produced by previous research are hybrid models that combine systematic reading behavior with random reading behavior.

On the complexity of inferring functional dependencies

Abstract The dependency inference problem is to find a cover for the set of functional dependencies that hold in a given relation. The problem has applications in relational database design and in query optimization. We show that this problem is solvable by a brute-force algorithm in Θ( n 2 2 n p log p ) time for a relation with p rows and n attributes. We show that for fixed n , time Ω( p log p ) is a lower bound. We also show that the exponentially of the time bound with respect to n is unavoidable. We prove this by showing that there are small relations where an exponential number of nontrivial dependencies hold. We also prove two exponential lower bounds that hold even for the case where no explicit representation of the dependency set is needed.

Effects of feedback and dwell time on eye typing speed and accuracy

Eye typing provides a means of communication that is especially useful for people with disabilities. However, most related research addresses technical issues in eye typing systems, and largely ignores design issues. This paper reports experiments studying the impact of auditory and visual feedback on user performance and experience. Results show that feedback impacts typing speed, accuracy, gaze behavior, and subjective experience. Also, the feedback should be matched with the dwell time. Short dwell times require simplified feedback to support the typing rhythm, whereas long dwell times allow extra information on the eye typing process. Both short and long dwell times benefit from combined visual and auditory feedback. Six guidelines for designing feedback for gaze-based text entry are provided.

Design issues of iDICT: a gaze-assisted translation aid

Eye-aware applications have existed for long, but mostly for very special and restricted target populations. We have designed and are currently implementing an eye-aware application, called iDict, which is a general-purpose translation aid aimed at mass markets. iDict monitors the users gaze path while s/he is reading text written in a foreign language. When the reader encounters difficulties, iDict steps in and provides assistance with the translation. To accomplish this, the system makes use of information obtained from reading research, a language model, and the user profile. This paper describes the idea of the iDict application, the design problems and the key solutions for resolving these problems.

Discussion: Interacting with parallel coordinates

Parallel coordinate visualizations have a reputation of being difficult to understand, expert-only representations. We argue that this reputation may be partially unfounded, because many of the parallel coordinate browser implementations lack essential features. This paper presents a survey of current interaction techniques for parallel coordinate browsers and compares them to the visualization design guidelines in the literature. In addition, we report our experiences with parallel coordinate browser prototypes, and describe an experiment where we studied the immediate usability of parallel coordinate visualizations. In the experiment, 16 database professionals performed a set of tasks both with the SQL query language and a parallel coordinate browser. The results show that although the subjects had doubts about the general usefulness of the parallel coordinate technique, they could perform the tasks more efficiently with a parallel coordinate browser than with their familiar query language interface.