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SHORT REPORT
Gaze and eye-tracking solutions for psychological research
Maria Laura Mele •Stefano Federici
Published online: 19 July 2012
ÓMarta Olivetti Belardinelli and Springer-Verlag 2012
Abstract Eye-tracking technology is a growing field used
to detect eye movements and analyze human processing of
visual information for interactive and diagnostic applica-
tions. Different domains in scientific research such as
neuroscience, experimental psychology, computer science
and human factors can benefit from eye-tracking methods
and techniques to unobtrusively investigate the quantitative
evidence underlying visual processes. In order to meet the
experimental requirements concerning the variety of
application fields, different gaze- and eye-tracking solu-
tions using high-speed cameras are being developed (e.g.,
eye-tracking glasses, head-mounted or desk-mounted sys-
tems), which are also compatible with other analysis
devices such as magnetic resonance imaging. This work
presents an overview of the main application fields of eye-
tracking methodology in psychological research. In par-
ticular, two innovative solutions will be shown: (1) the SMI
RED-M eye-tracker, a high performance portable remote
eye-tracker suitable for different settings, that requires
maximum mobility and flexibility; (2) a wearable mobile
gaze-tracking device—the SMI eye-tracking glasses—
which is suitable for real-world and virtual environment
research. For each kind of technology, the functions and
different possibilities of application in experimental
psychology will be described by focusing on some exam-
ples of experimental tasks (i.e., visual search, reading,
natural tasks, scene viewing and other information
processing) and theoretical approaches (e.g., embodied
cognition).
Keywords Portable eye-tracking technology Remote
eye-tracking technology Psychological research
Introduction
Eye-tracking technology is a set of methods and techniques
used to detect and record the activities of eye movements.
The research on eye movements has spread over the years
along with advances in eye-tracking technology and psy-
chological theory on the relationship between eye behavior
and cognitive processes. Since eye movements provide an
insight into problem solving, reasoning, mental imagery
and search strategies (Jacob and Karn 2003), research in
psychology has largely used objective methods to investi-
gate how eye movements are related to cognitive processes
during visual tasks. Over the past 30 years, remarkable
improvements in the development of eye-tracking systems
have permitted practitioners to obtain more accurate eye-
gaze measurements with less intrusive technologies. A
wide variety of eye-tracking techniques are available, and
they can be divided from a system analysis viewpoint
into diagnostic or interactive techniques. ‘‘In its diagnostic
role, the eye-tracker provides objective and quantitative
evidence of the user’s visual and (overt) attentional pro-
cesses’’(Duchowski 2002, p. 455), whereas, in its interac-
tive role, the eye-tracker is used as interactive system
responding to or interacting with the user on the basis of
observed eye movements. Different eye-tracking systems
M. L. Mele (&)
Department of Psychology, Sapienza University of Rome,
Rome, Italy
e-mail: marialaura.mele@uniroma1.it
S. Federici
Department of Human Science and Education,
University of Perugia, Perugia, Italy
123
Cogn Process (2012) 13 (Suppl 1):S261–S265
DOI 10.1007/s10339-012-0499-z
have been developed to record eye movements during
visual interaction or as input devices for communication
and control. This work focuses on the diagnostic role of
eye-tracking systems in different fields of experimental
psychology by highlighting how objective measures
underlying a user’s cognitive processes can be obtained
with different eye-tracking technologies through unobtru-
sive methods.
New eye-tracking solutions: the SMI RED-M
and the SMI eye-tracking glasses
Traditionally, research on eye movements has used eye-
tracking technologies by means of invasive techniques that
required supplemental components such as contact lenses,
chin rests or bite bars (Fig. 1). Due to the physical con-
straints imposed on subjects, these technologies were often
uncomfortable and suitable only for certain experimental
contexts. To overcome these limitations, video-based
techniques have been proposed to detect the eye position
and gaze direction by means of equipment that is increas-
ingly less intrusive and more accurate (Holmqvist et al.
2011). Recently, different gaze and eye-tracking solutions
that use head-mounted, desk-mounted or eyeglass-mounted
high-speed cameras—which are compatible with other
analysis devices such as magnetic resonance imaging
(MRI)—have been developed to meet the wide variety of
application domains. This paper will examine the possi-
bilities offered by two innovative solutions in particular:
(1) the SMI RED-M eye-tracker; and (2) the SMI eye-
tracking glasses; two new camera-based technologies have
recently released by SensoMotoric Instruments (http://
www.smivision.com).
SMI RED-M eye-tracker
The SMI RED-M is an eye-tracking technology developed
by SensoMotoric Instruments (SMI) to set up experimental
settings requiring the minimum intrusiveness in the
recording instrumentation. The SMI RED-M is a USB-
powered portable and ultra-light remote contact-free sys-
tem that can be used on a desktop PC monitor, a personal
laptop or a tablet. The technology, along with the SMI
Experiment Suite
TM
360°design and analysis software,
constitutes a comprehensive portable eye-tracking solution.
By means of automatic eye-tracking and head movement
compensation solutions, the system provides reliable bin-
ocular gaze and pupil data in a highly mobile and flexible
way, regardless of the peculiarities of subjects involved in
the experimentation (e.g., eye color, age, glasses, contact
lenses) or environmental conditions (e.g., light of the room,
position of the screen).
Different measurement functions to control and analyze
the subjects’ performances are available: gaze position on
surfaces; pupil size; and 3D head and eye position. The
system provides data extensions that can be easily pro-
cessed by the SMI BeGaze
TM
analysis and visualization
software (Fig. 2) and other statistics software (e.g.,
MATLABÒ, SPSSÒ, Excel
TM
). Moreover, eye-tracking
data can be integrated with individual setups such as the
E-PrimeÒ, Python or MATLABÒsoftware, and custom
applications written in different programming languages
(e.g., C/C ?? or -NET), supporting co-registrations with
other kinds of data (e.g., MRI).
SMI eye-tracking glasses
In 2012, SMI SensoMotoric Instruments proposed a new
fully mobile gaze-tracking device, the SMI Eye-tracking
Glasses, which are a non-invasive and robust system
designed to be used like a common pair of glasses (weight
75 g) in different environmental studies, e.g., driving
research, visual perception research or indoor/outdoor
research. The system is equipped with an HD scene camera
(resolution 1,280 9960 p) and eye glasses that can be
interchanged according to the experimental environment
light (indoor/outdoor use). Thanks to an automatic parallax
compensation mechanism that obviates the need for man-
ual adjustments, the SMI Eye-tracking Glasses provide
reliable binocular eye-tracking data in both real-time and
recorded data observations, and it is easily integrable with
other mobile technologies and sensors such as EEG or
GPS. The system also includes a mobile recording unit and
an optional software package—the BeGazeTM software—
developed to aggregate data by a semi-automated dynamic
Area of Interest (AOI) analysis with no need to use active
markers (Fig. 3).
Fig. 1 A rudimental apparatus for tracking eye movements by means
of the direct contact of a lens with the cornea (Mele and Federici
2012)
S262 Cogn Process (2012) 13 (Suppl 1):S261–S265
123
Fig. 2 Heat map created with
SMI BeGaze
TM
eye-tracking
analysis software (http://www.
smivision.com/egts)
Fig. 3 Key eye-tracking data
on selected areas of interest
(AOIs) of a print ad created with
SMI BeGaze eye-tracking
analysis software
(http://www.flickr.com/photos/
smieyetracking/)
Cogn Process (2012) 13 (Suppl 1):S261–S265 S263
123
Application of eye-tracking technology in psychological
research
Eye movements are the result of the interaction between
cognitive and perceptual processes (Richardson and John-
son 2008), and they can be a powerful way to investigate
psychological processes such as language processing,
image processing, auditory processing, memory, social
cognition and decision-making in an unobtrusive and
accurate way. As follows, different application possibilities
of eye-tracking technologies in experimental psychology
will be described by focusing on examples of experimental
tasks: (1) visual search, (2) reading, (3) natural tasks, (4)
scene viewing and (5) other information processing.
Visual search
The analysis of eye behavior in visual search tasks reveals
objective information on how humans perceive a visual
scene in situations that require visual target detection. Eye-
tracking visual search tasks can be divided according to
the nature of the stimuli used, such as alphanumeric, textual
or text-like stimuli, pictorial stimuli, complex arrays or
objects (Duchowski 2002). In the investigation of human
behavior related to visual search tasks, subjects are tradi-
tionally asked to search for a given target and discriminate
it among several non-targets that differ from the target.
Response times, eye-gaze parameters and accuracy of
responses are relevant measures to be taken into account in
visual search studies. Given the nature of the tasks, remote
eye-tracking technologies combined with design software
are the best solution for gaze-tracking experiments and
visual stimuli presentation. In fact, this kind of technology
(e.g., the SMI RED500 or RED-M products) provides
researchers a flexible and robust system to manage their
experiments and, at the same time, permit them to arrange
a comfortable setting by minimizing the impact of
recording instrumentation on subjects’ performance.
Reading
Since the second half of the 1970 s, psychology has
adopted eye-tracking methodologies to investigate (overt)
visual attention in reading experimental tasks. The first
studies on eye movements in text reading led researchers to
identify the most peculiar eye movement characteristics in
reading, such as the average duration of eye fixations and
saccades and the variables that influence eye movement
performance such as textual, typographical or contextual
features (Rayner 1998). The current remote eye-tracking
systems allow practitioners to accurately operate and reg-
ister eye movements during reading experiments for
descriptive analyses or even to modulate the stimulus
display in real-time according to the subject’s gaze position
in different displays such as tablets, desktop screens, papers
or other supports. For this field of studies, remote eye-
tracking technologies providing high data quality and high-
speed performance are required to accurately measure
saccades and shortest latencies remote contact-free setups
(e.g., SMI RED 500 or iView X
TM
Hi-Speed products).
Natural tasks
The examples of application previously reported are often
set up to be conducted in artificial laboratory settings;
therefore, different studies investigated complex stimuli
such as natural scenery. Numerous are the dynamic situa-
tions that have been observed in the eye-tracking literature
(e.g., driving, sport, imagery tasks, virtual reality and
usability studies), which often involves different kinds of
perceptual feedback such as haptic or acoustic information.
Thanks to recent advancements in portable eye-tracking
technologies (e.g., the head-mounted iView X
TM
HED or
the SMI eye-tracking glasses), today it is easy to collect
eye movements in more natural situations—usually
requiring unconstrained eyes, head and hand movements
(Duchowski 2002)—with full freedom of movement in
indoor and outdoor settings.
Scene viewing
Since the visual information processing mechanisms of
human vision have emerged as a relevant issue in the study
of perception and cognition, the investigation of eye
movements by means of eye-tracking technologies has
revealed a powerful way to understand scene viewing. Due
to the non-intrusiveness and high portability of modern
eye-tracking technologies, the measurement of eye move-
ment patterns, related to visual and cognitive information
processing, can be conducted in a wide variety of experi-
mental contexts and situations. By means of wearable eye-
tracking technologies, researchers can obtain reliable and
unobtrusive on-line measures of eye movements and
parameters to study eye behaviors during complex visual-
cognitive tasks, analyze the way in which subjects acquire
environmental information, and investigate how informa-
tion in visual environments is dynamically processed
(Henderson and Hollingworth 1998).
Information processing in other cognitive tasks
Eye movement studies on information processing involve a
large number of other domains that can be divided
according to the nature of the task (Rayner 1998). Studies
on numerical and arithmetical reading and analysis, prob-
lem solving, multisensory tasks such as auditory language
S264 Cogn Process (2012) 13 (Suppl 1):S261–S265
123
processing, face perception and visual training can benefit
from high performance eye-tracking systems, which are
suitable for a wide range of research areas and are com-
patible with other analysis devices such as functional
magnetic resonance imaging (fMRI), magnetoencephalog-
raphy (MEG), electroencephalography (EEG), or pupil-
lometry (e.g., the iView X
TM
MRI-LR system).
The application of eye-tracking technology in the study
of embodied cognition
Since cognitive processes are deeply rooted in the body’s
interactions with the world (Wilson 2002), eye-tracking
methodology might be a privileged way to study embodied
cognition. Cognitive sciences agree that cognition is the
result of both cognitive processes and situated environ-
mental contexts (Barsalou 1999; Clark and Chalmers
1998). Some authors recently pointed out that eye move-
ments interacting with environmental spatial stimuli
influence spatial reasoning (Grant and Spivey 2003) and, in
a reciprocal way, act as an embodied mechanism guiding
cognitive processing (Thomas and Lleras 2007). In the
past, many studies have used different kinds of eye-track-
ing solutions to investigate how eye behavior affects
thought and enhances reasoning(Shimojima and Katagiri
2012), and how beliefs and attitudes affect eye movements,
predicting implicit associations (Mele and Federici 2013).
These studies highlight how eye-tracking technologies can
be particularly suitable for experimental paradigms, which
assume theories of grounded cognition (Barsalou 2008,
2010).
Conclusion
Different domains in scientific research such as neurosci-
ence, experimental psychology or human factor science can
benefit from eye-tracking methodology to investigate
visual processes. An overview of the different possibilities
for applying eye-tracking in psychology has been shown,
with a special attention to two recent SMI solutions. In this
paper, we have presented examples of eye-tracking appli-
cation in psychology by showing different experimental
tasks. Moreover, since the study of visual behavior is a
privileged way to understand the relationship between
body and cognition, we focused on the application of eye-
tracking technology in the theories of grounded cognition.
Conflict of interest This supplement was not sponsored by outside
commercial interests. It was funded entirely by ECONA, Via dei
Marsi, 78, 00185 Roma, Italy.
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