Book Review: Eye Tracking: A Comprehensive Guide to Methods and Measures
Fifty years ago it was virtually impossible to carry out funded work in the United Kingdom on eye movement control in reading. For example, the Social Science Research Council at that time, possibly influenced by three very negative reviews of the subject by Tinker, the last in 1958 (Tinker, 1958) loftily declared the topic a dead end. Now, virtually all psychology departments provide a home for at least one eye movement researcher (and sometimes ten) The reason? Possibly a single paper by McConkie and Rayner (1975) involving the first use of a gaze contingent procedure, in which where the observer was looking determined what the observer saw. This was undoubtedly a technological tour de force, albeit somewhat flawed (but more on that anon) Those initial data on the asymmetric perceptual span in reading are still cited (and are broadly correct) A tidal wave of research followed. Indeed, attendance at one particular annual conference grew so fast that a speaker calculated by mid century the population of the world would be engaged in recording eye movements and Russo (1978) published a paper with the engaging title, "Eye fixations can save the world." Well, did they? Some part of the answer can be found in this book, claiming to be a comprehensive guide to "methods and measures employed in eye tracking" Certainly not restricted to reading, it reflects the massive expansion of eye movement recording into virtually all areas of cognitive psychology. Notwithstanding other indirect indices, in particular brain imaging, eye movement recording remains the paradigm of choice for virtually all psycholinguistic research, as well as much work on scene perception, motor control, the visual world paradigm (linking speech and action) binocularity, visual attention, and a great many more mundane applications. This book is an instruction manual for the would be researcher, offering answers to a host of critical technical questions. It is well worth the modest purchase price. Although it claims to be about instruments in general, in truth only a single class of instrument gets much of a look in. These are the video based pupil centre computation devices, such as the Eyelink TM system developed by Stampe and Reingold in the 1990s (Stampe, 1993; Stampe Reingold, 1995) I was disappointed by this, because there are other, cheaper, and equally accurate alternatives; I accept it is defensible, because these devices are now the popular instrument of choice. In particular, the advent of head mounted versions has made the measurement of eye movements in the real world relatively easy (making a cup of tea much favoured as target occupation) However, to the degree that the book restricts itself to a particular class of commercial device, in places it is quite close to "product placement" and I confess to feeling a little uncomfortable about this. The Dual Purkinje eye tracker, for example, is still widely used, as is the scleral coil. Both are dismissed here in a few sentences. The book provides a very sound introduction to the topic for anyone intending to set up an eye tracking laboratory using a video system (and that may be the majority of psychologists) In that sense it earns its keep. It is at its strongest and most interesting dealing with visualization techniques: for example, the various ways of representing scanpaths and the use of heat maps in the
Quarterly journal of experimental psychology