Gaze-contingency paradigm
Encyclopedia
The gaze-contingency paradigm is a general term for techniques allowing to change the display on a computer screen in function of where the viewer is looking.
Gaze-contingent techniques are part of the eye movement field of study in psychology. Over the past century, the way the eyes move in human activities as diverse as playing sport, viewing works of art, piloting aircraft, exploring visual scenes, recognizing face or facial expressions, and reading language and music, has revealed some of the ocular and psychological mechanisms involved in the visual system.
The gaze-contingent techniques aim to overcome limitations inherent to simple eye-movement recording. Indeed, due to an imperfect coupling between overt and covert attentions (Posner, 1980), it is not possible to exactly know which visual information the viewer is processing based on the fixation locations. By controlling precisely the information projected in different parts of the visual field, the gaze-contingent techniques permit to disentangle what is fixated and what is processed.
The technical principle of the paradigm involves a computer interfaced with both an eye-movement tracking system (Eye-tracker
) and a display of the visual stimulus
. A fast computer, eye-tracker and display allow reliable results. In gaze-contingent paradigms the stimulus display is continuously updated as a function of the observers' current gaze position. Therefore, the gaze-contingent technique is a powerful method to control for the visual information feeding the visual system
and to isolate information use.
The gaze-contingent technique is the basis of various experimental paradigms, each of them allowing to investigate specific cognitive processes.
In the moving window paradigm (e.g., Reder, 1973; McConkie & Rayner, 1975) only the part of the visual field
around the gaze location (foveal information) is displayed normally, the surrounding part of the visual field (extrafoveal and peripheral
information) being altered (removed for visual scenes or replaced by chains of X in reading).
The moving mask paradigm (e.g. Rayner & Bertera, 1979) is a reverse technique in comparison with the moving window paradigm. It dynamically obscures central vision (or replaces letters with X in reading), permitting only extrafoveal information use.
In the boundary paradigm (e.g., Rayner, 1975; Balota, Pollatsek & Rayner, 1985; Miellet & Sparrow, 2004), an extrafoveal prime (a homophone
in reading for example) is replaced by the target stimulus when the eyes cross an invisible boundary around the target area.
The parafoveal magnification paradigm (Miellet, O'Donnell & Sereno, 2009) compensates for how visual acuity drops off as a function of retinal eccentricity. On each fixation and in real time, parafoveal text is magnified to equalize its perceptual impact with that of concurrent foveal text.
In the language
domain this method has been successfully used in natural reading
. The study of eye movements in reading
allowed researchers to map out the perceptual span
(moving window paradigm: e.g., Reder, 1973; McConkie & Rayner, 1975), the nature of the extrafoveal information extracted during a fixation, for instance orthographic and phonological information (boundary paradigm: e.g., Rayner, 1975; Balota, Pollatsek & Rayner, 1985; Miellet & Sparrow, 2004) or the relative influence of attention
versus visual acuity
drop-off in the perceptual span (parafoveal magnification paradigm: Miellet, O'Donnell & Sereno, 2009).
The gaze-contingent technique has been adapted in other tasks than reading. The moving window paradigm has been used to study the effect of culture in face recognition
for example (Caldara, Zhou & Miellet, 2010). The moving mask paradigm has been used in visual learning (Castelhano & Henderson, 2008) or visual search
of animals in natural visual scenes (Miellet, Zhou, He, Rodger & Caldara, 2010).
The various gaze-contingent techniques has given eye-movement researchers the ability to observe the processing of visual input in much greater detail (particularly its temporal characteristics), the perceptual span, and the nature of central
versus peripheral
processing in reading.
Gaze-contingent techniques are part of the eye movement field of study in psychology. Over the past century, the way the eyes move in human activities as diverse as playing sport, viewing works of art, piloting aircraft, exploring visual scenes, recognizing face or facial expressions, and reading language and music, has revealed some of the ocular and psychological mechanisms involved in the visual system.
The gaze-contingent techniques aim to overcome limitations inherent to simple eye-movement recording. Indeed, due to an imperfect coupling between overt and covert attentions (Posner, 1980), it is not possible to exactly know which visual information the viewer is processing based on the fixation locations. By controlling precisely the information projected in different parts of the visual field, the gaze-contingent techniques permit to disentangle what is fixated and what is processed.
The technical principle of the paradigm involves a computer interfaced with both an eye-movement tracking system (Eye-tracker
Eye tracking
Eye tracking is the process of measuring either the point of gaze or the motion of an eye relative to the head. An eye tracker is a device for measuring eye positions and eye movement. Eye trackers are used in research on the visual system, in psychology, in cognitive linguistics and in product...
) and a display of the visual stimulus
Stimulus (physiology)
In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity....
. A fast computer, eye-tracker and display allow reliable results. In gaze-contingent paradigms the stimulus display is continuously updated as a function of the observers' current gaze position. Therefore, the gaze-contingent technique is a powerful method to control for the visual information feeding the visual system
Visual system
The visual system is the part of the central nervous system which enables organisms to process visual detail, as well as enabling several non-image forming photoresponse functions. It interprets information from visible light to build a representation of the surrounding world...
and to isolate information use.
The gaze-contingent technique is the basis of various experimental paradigms, each of them allowing to investigate specific cognitive processes.
In the moving window paradigm (e.g., Reder, 1973; McConkie & Rayner, 1975) only the part of the visual field
Visual field
The term visual field is sometimes used as a synonym to field of view, though they do not designate the same thing. The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments", while 'field of view' "refers to the physical...
around the gaze location (foveal information) is displayed normally, the surrounding part of the visual field (extrafoveal and peripheral
Peripheral vision
Peripheral vision is a part of vision that occurs outside the very center of gaze. There is a broad set of non-central points in the field of view that is included in the notion of peripheral vision...
information) being altered (removed for visual scenes or replaced by chains of X in reading).
The moving mask paradigm (e.g. Rayner & Bertera, 1979) is a reverse technique in comparison with the moving window paradigm. It dynamically obscures central vision (or replaces letters with X in reading), permitting only extrafoveal information use.
In the boundary paradigm (e.g., Rayner, 1975; Balota, Pollatsek & Rayner, 1985; Miellet & Sparrow, 2004), an extrafoveal prime (a homophone
Homophone
A homophone is a word that is pronounced the same as another word but differs in meaning. The words may be spelled the same, such as rose and rose , or differently, such as carat, caret, and carrot, or to, two, and too. Homophones that are spelled the same are also both homographs and homonyms...
in reading for example) is replaced by the target stimulus when the eyes cross an invisible boundary around the target area.
The parafoveal magnification paradigm (Miellet, O'Donnell & Sereno, 2009) compensates for how visual acuity drops off as a function of retinal eccentricity. On each fixation and in real time, parafoveal text is magnified to equalize its perceptual impact with that of concurrent foveal text.
In the language
Language
Language may refer either to the specifically human capacity for acquiring and using complex systems of communication, or to a specific instance of such a system of complex communication...
domain this method has been successfully used in natural reading
Reading (process)
Reading is a complex cognitive process of decoding symbols for the intention of constructing or deriving meaning . It is a means of language acquisition, of communication, and of sharing information and ideas...
. The study of eye movements in reading
Eye movement in language reading
Eye movement in reading involves visual processing of words. This was first described by the French ophthalmologist Louis Émile Javal in the late 19th century. He reported that eyes do not move continuously along a line of text, but make short rapid movements intermingled with short stops...
allowed researchers to map out the perceptual span
Vision span
Vision span or perceptual span is the angular span , within which the human eye has sharp enough vision to read text. The visual field of the human eye spans approximately 120 degrees of arc. However, most of that arc is peripheral vision. The human eye has much greater resolution in the...
(moving window paradigm: e.g., Reder, 1973; McConkie & Rayner, 1975), the nature of the extrafoveal information extracted during a fixation, for instance orthographic and phonological information (boundary paradigm: e.g., Rayner, 1975; Balota, Pollatsek & Rayner, 1985; Miellet & Sparrow, 2004) or the relative influence of attention
Attention
Attention is the cognitive process of paying attention to one aspect of the environment while ignoring others. Attention is one of the most intensely studied topics within psychology and cognitive neuroscience....
versus visual acuity
Visual acuity
Visual acuity is acuteness or clearness of vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain....
drop-off in the perceptual span (parafoveal magnification paradigm: Miellet, O'Donnell & Sereno, 2009).
The gaze-contingent technique has been adapted in other tasks than reading. The moving window paradigm has been used to study the effect of culture in face recognition
Face perception
Face perception is the process by which the brain and mind understand and interpret the face, particularly the human face.The human face's proportions and expressions are important to identify origin, emotional tendencies, health qualities, and some social information. From birth, faces are...
for example (Caldara, Zhou & Miellet, 2010). The moving mask paradigm has been used in visual learning (Castelhano & Henderson, 2008) or visual search
Visual search
Visual search is a type of perceptual task requiring attention that typically involves an active scan of the visual environment for a particular object or feature among other objects or features . Visual search can take place either with or without eye movements...
of animals in natural visual scenes (Miellet, Zhou, He, Rodger & Caldara, 2010).
The various gaze-contingent techniques has given eye-movement researchers the ability to observe the processing of visual input in much greater detail (particularly its temporal characteristics), the perceptual span, and the nature of central
Fovea
The fovea centralis, also generally known as the fovea , is a part of the eye, located in the center of the macula region of the retina....
versus peripheral
Peripheral vision
Peripheral vision is a part of vision that occurs outside the very center of gaze. There is a broad set of non-central points in the field of view that is included in the notion of peripheral vision...
processing in reading.
See also
- Eye movement
- Eye trackingEye trackingEye tracking is the process of measuring either the point of gaze or the motion of an eye relative to the head. An eye tracker is a device for measuring eye positions and eye movement. Eye trackers are used in research on the visual system, in psychology, in cognitive linguistics and in product...
- Eye movement in language readingEye movement in language readingEye movement in reading involves visual processing of words. This was first described by the French ophthalmologist Louis Émile Javal in the late 19th century. He reported that eyes do not move continuously along a line of text, but make short rapid movements intermingled with short stops...
- Eye movement in music readingEye movement in music readingEye movement in music reading is the scanning of a musical score by a musician's eyes. This usually occurs as the music is read during performance, although musicians sometimes scan music silently to study it, and sometimes perform from memory without score. The phenomenon has been studied by...
- Foveated imagingFoveated imagingthumb|16:1 compression. Foveated image with fixation point at Stephen F. Austin statue.Foveated imaging is a digital image processing technique in which the image resolution, or amount of detail, varies across the image according to one or more "fixation points."A fixation point indicates the...
- Attention#Overt and covert attention