Eye Tracking Methodology; Theory and Practice

Citation

Chamberlain, L. (2007), "Eye Tracking Methodology; Theory and Practice", Qualitative Market Research, Vol. 10 No. 2, pp. 217-220. https://doi.org/10.1108/13522750710740862

Eye tracking techniques have been implemented in an increasing number of research studies in recent years, particularly in the field of marketing. Andrew Duchowski's book Eye Tracking Methodology; Theory and Practice is a comprehensive and detailed guide to the theoretical background and implementation of eye tracking methods which can be used in a variety of research contexts. This guide highlights the practicalities of conducting eye tracking experiments. Although it is written from a computer science perspective it is not only accessible to researchers from all disciplines, but also considers a broad range of interdisciplinary research and application topics.

The book concentrates on three main areas, firstly the theoretical background for eye tracking research, namely the human visual system. Secondly, the eye tracking systems that can be used in research, considering techniques, hardware, software, calibration and data analysis. Thirdly, the applications of eye tracking techniques, looking in detail at neuroscience and psychology, industrial engineering, marketing and advertising and computer science. Essentially, Duchowski provides researchers with an invaluable resource that is essential for any individual conducting eye tracking experiments, which not only serves as a reference point for theoretical considerations, but also a practical guide to the fundamentals of using eye tracking equipment. In light of this, Duchowski provides an important resource, as although eye tracking methods are used by a number of researchers in different fields, due to a lack of information and education on the appropriate methodology the technology is not as widely used as arguably it could be. Overall, Duchowski identifies three main domains which ultimately serve to benefit from advances in eye tracking research: visual perception; human computer interaction and computer graphics. Such benefits can only be accrued with a more developed understanding of eye tracking research and an increased use of the appropriate methodology, a goal which this book will surely help to achieve.

Marketing researchers have often been criticised for reliance upon the use of questionnaires to collect quantitative data and a failure to explore alternative methodological options available. In answer to such criticism, the use of eye tracking technology can be utilised to collect a vast array of data in a variety of research contexts as highlighted in Duchowskis' book. Indeed, marketing researchers (Pieters and Warlop, 1999; Pieters and Wedel, 2004; Pieters et al., 1999), have identified the opportunities and benefits of eye tracking techniques in marketing and have published a variety of papers using the method. Given the uptake of eye tracking research in the field of marketing, this book provides a comprehensive reference point, unlike any other currently in publication.

As previously indicated, this book is divided into three main sections. The first section looks at the theoretical background to eye tracking research, specifically the human visual system. This section considers the motivation for the study of eye movements from both psychological and physiological perspectives. Duchowski takes the time to highlight the historical development of theory on visual attention, from 1925 to more recent theoretical developments in the area and identifies the main areas where research on visual attention has yet to address. The reader is then provided with a detailed section about the physiology of the human visual system which outlines the brain and the visual pathways relevant to eye movements and attention, with specific attention paid to the structure of the eye. This section then goes on to look at the established experimental paradigms for the measurement of visual performance parameters and models of eye movements in detail. The provision of an overview of the essential theoretical background and the detailed description of the physiology of the human visual system, specifically in an eye tracking context, is of great benefit to the reader and is a concise, although not exhaustive, introduction to the area. For researchers already implementing this method and those investigating it as a possibility, this comprehensive review of the fundamental theories and physiological points is likely to be very useful.

The second section of this book looks at eye tracking technology, the different systems available and the practicalities of using such systems. Four main eye tracking techniques are identified: electro‐oculography (EOG); scleral contact lens/search coil; photo‐oculography (POG); and video‐oculography (VOG). Duchowski provides an explanation of each technique, the equipment required to use it and elaborates on types of data that each technique can be used to capture. In fact, a major strength of this book is the attention given to the practical issues associated with eye tracking techniques, such as system hardware installation, system software development and system calibration. In the chapter on system hardware installation integration issues are explored, specifically those concerning the integration of the eye tracker into a graphics system, the requirements and issues associated with the installation of such a system. Issues surrounding the mapping of eye tracker coordinates to the appropriate application program's reference frame are considered in the chapter on system software development. A description of how systems are calibrated, with emphasis upon the importance of correct calibration, is provided in the chapter on system calibration. The final chapter in this section of the book is devoted to eye movement analysis, where Duchowski focuses on transforming raw eye movement data into a more meaningful format. Issues such as the elimination of excessive noise in the eye movement signal, 2D and 3D analyses are presented.

Duchowski draws upon his own experiences at Clemson University regarding the set up and installation of equipment to highlight pitfalls and problems encountered. This serves to highlight that the equipment we are dealing with here is complex and (as I know from personal experience) has many nuances which can lead to complications. This approach is appealing as Duchowski does not lecture on this subject but instead provides a very helpful guide which encourages the use of this technology, even though at first it may appear daunting due to its complexity. Indeed, this complexity is a criticism that marketing researchers have levied against the use of such technology and thus provided strength to the argument for the use of questionnaires as the preferred method by which to collect quantitative data. Having said this, Duchowski does not patronise the experienced eye tracker in this approach. Quite the opposite, he highlights pertinent issues that researchers may have already experienced or indeed had not thought could be an issue, therefore alerting them to potential pitfalls in future research.

The third section of this book identifies four fields in which eye tracking has been used for different research purposes; neuroscience and psychology, engineering, marketing, advertising and computer science. The application of eye tracking to neuroscience and psychology has occurred in a wide variety of research studies. Duchowski highlights the inter‐dependence of neuroscience and psychology regarding human vision and looks in detail at a number of research studies concerning vision during reading, visual search, perception of art and vision in virtual and natural environments. Of particular note is the discussion of the possibilities regarding the use of eye tracking technology in conjunction with other methods, for example brain imaging techniques.

Duchowski also explores eye tracking research that has been conducted in industrial engineering which has focussed on the use of such techniques to examine human attentional behaviour in the context of present and future environments in which individuals will or do work. One significant benefit of this application is the ability to examine human interaction and behaviour in environments, specifically in contexts where safety is of critical importance. Although traditional methods of performance measurement, for example reaction time and accuracy are often used, eye tracking techniques can provide insights into the visual, cognitive and attention aspects of human performance. In this section eye tracking techniques applied to aviation, driving and visual inspection are explored, with particular emphasis on the development of sophisticated stimulators for tasks.

The ways in which eye tracking techniques can and have been used to aid the advancement of research regarding the understanding of consumer actions are developed in the chapter on marketing and advertising applications. Particular attention is afforded to results from research that has looked at visual attention and copy testing, print advertisements, advertising “wearout” and ad placement. Duchowski does highlight that there are many opportunities for the use of eye tracking techniques in marketing and advertising research. However, he reports that there is little evidence of marketing research in this context.

In the chapter on computer science applications of eye tracking techniques a discussion of two types of interactive applications ensues: selective application using the eye tracker as an input device and gaze‐contingent application which is a type of display system where the information presented to the viewer is generally manipulated to match the processing capability of the human visual system. The detailed consideration of computer science research that has utilised eye tracking techniques serves to identify the vast array of research opportunities such technology can lend to the field. Indeed, Duchowski predicts that in this research field, specifically in the context of usability studies, eye tracking methodology will flourish.

Drawing upon research conducted in a variety of fields and from his own experiences in the use of eye tracking techniques, Duchowski offers key advice on the process of conducting eye tracking research and inspires thought concerning the many possibilities that the applications of such techniques can deliver. It is a clear, concise and accessible text, which uses clear diagrams, illustrative photographs and data display to elaborate and clarify main points. Overall, this is a comprehensive guide to eye tracking methodology that encompasses theory and practical issues regarding the implementation of this technology. It is an essential read for any researcher or practitioner whether they be considering the use of eye tracking techniques to generate data, or are already using such methods and as such it is highly recommended.