Eye movement in reading

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Eye movement in reading involves the visual processing of written text. This was 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 (saccades) intermingled with short stops (fixations). Javal's observations were characterised by a reliance on naked-eye observation of eye movement in the absence of technology. From the late 19th to the mid-20th century, investigators used early tracking technologies to assist their observation, in a research climate that emphasised the measurement of human behaviour and skill for educational ends. Most basic knowledge about eye movement was obtained during this period. Since the mid-20th century, there have been three major changes: the development of non-invasive eye-movement tracking equipment; the introduction of computer technology to enhance the power of this equipment to pick up, record, and process the huge volume of data that eye movement generates; and the emergence of cognitive psychology as a theoretical and methodological framework within which reading processes are examined. Sereno & Rayner (2003) believed that the best current approach to discover immediate signs of word recognition is through recordings of eye movement and event-related potential.

Contents

History

Until the second half of the 19th century, researchers had at their disposal three methods of investigating eye movement. The first, unaided observation, yielded only small amounts of data that would be considered unreliable by today's scientific standards. This lack of reliability arises from the fact that eye movement occurs frequently, rapidly, and over small angles, to the extent that it is impossible for an experimenter to perceive and record the data fully and accurately without technological assistance. The other method was self-observation, now considered to be of doubtful status in a scientific context. Despite this, some knowledge appears to have been produced from introspection and naked-eye observation. For example, Ibn al Haytham, a medical man in 11th-century Egypt, is reported to have written of reading in terms of a series of quick movements and to have realised that readers use peripheral as well as central vision. [1]

Leonardo da Vinci: The eye has a central line and everything that reaches the eye through this central line can be seen distinctly. Eye Line of sight.jpg
Leonardo da Vinci: The eye has a central line and everything that reaches the eye through this central line can be seen distinctly.

Leonardo da Vinci (1452–1519) may have been the first in Europe to recognize certain special optical qualities of the eye. He derived his insights partly through introspection but mainly through a process that could be described as optical modelling. Based on dissection of the human eye he made experiments with water-filled crystal balls. He wrote "The function of the human eye, ... was described by a large number of authors in a certain way. But I found it to be completely different." [2]

His main experimental finding was that there is only distinct and clear vision at the "line of sight", the optical axis that ends at the fovea. Although he did not use these words literally he actually is the father of the modern distinction between foveal vision (where the observer fixates on the object of interest) and peripheral vision. However, Leonardo did not know that the retina is the sensible layer, he still believed that the lens is the organ of vision.

There appear to be no records of eye movement research until the early 19th century. At first, the chief concern was to describe the eye as a physiological and mechanical moving object, the most serious attempt being Hermann von Helmholtz's major work Handbook of physiological optics (1866). The physiological approach was gradually superseded by interest in the psychological aspects of visual input, in eye movement as a functional component of visual tasks.

The subsequent decades saw more elaborate attempts to interpret eye movement, including a claim that meaningful text requires fewer fixations to read than random strings of letters. [3] In 1879, the French ophthalmologist Louis Émile Javal used a mirror on one side of a page to observe eye movement in silent reading, and found that it involves a succession of discontinuous individual movements for which he coined the term saccades. In 1898, Erdmann & Dodge used a hand-mirror to estimate average fixation duration and saccade length with surprising accuracy.

Early tracking technology

Eye tracking device is a tool created to help measure eye and head movements. The first devices for tracking eye movement took two main forms: those that relied on a mechanical connection between participant and recording instrument, and those in which light or some other form of electromagnetic energy was directed at the participant's eyes and its reflection measured and recorded. In 1883, Lamare was the first to use a mechanical connection, by placing a blunt needle on the participant's upper eyelid. The needle picked up the sound produced by each saccade and transmitted it as a faint clicking to the experimenter's ear through an amplifying membrane and a rubber tube. The rationale behind this device was that saccades are easier to perceive and register aurally than visually. [4] In 1889, Edmund B. Delabarre invented a system of recording eye movement directly onto a rotating drum by means of a stylus with a direct mechanical connection to the cornea. [5] Other devices involving physical contact with the surface of the eyes were developed and used from the end of the 19th century until the late 1920s; these included such items as rubber balloons and eye caps.

Mechanical systems suffered three serious disadvantages: questionable accuracy due to slippage of the physical connection, the considerable discomfort caused to participants by the direct mechanical connection (and consequently great difficulty in persuading people to participate), and issues of ecological validity, since participants' experience of reading in trials was significantly different from the normal reading experience. Despite these drawbacks, mechanical devices were used in eye movement research well into the 20th century.

Attempts were soon made to overcome these problems. One solution was to use electromagnetic energy rather than a mechanical connection. In the "Dodge technique", a beam of light was directed at the cornea, focused by a system of lenses and then recorded on a moveable photographic plate. Erdmann & Dodge [6] used this technique to claim that there is little or no perception during saccades, a finding that was later confirmed by Utall & Smith using more sophisticated equipment. The photographic plate in the Dodge technique was soon replaced with a film camera, but was still plagued by problems of accuracy, due to the difficulty of keeping all parts of the equipment perfectly aligned throughout a trial and accurately compensating for the distortion caused by the diffractive qualities of photographic lenses. In addition, it was usually necessary to restrain a participant's head by using an uncomfortable bite-bar or head-clamp.

In 1922, Schott pioneered a further advance called electro-oculography (EOG), a method of recording the electrical potential between the cornea and the retina. [7] Electrodes may be covered with special contact paste before being placed on the skin. So, it is now unnecessary to make incisions in patient's skin. A common misconception about EOG is that the measured potential is the electromyogram of extraocular muscles. In fact, it is only the projection of eye dipole to the skin, because higher frequencies, corresponding to EMG, are filtered out. EOG delivered considerable improvements in accuracy and reliability, which explain its continued use by experimentalists for many decades. [8] [9] [10]

Modern eye tracking

Four major cognitive systems are involved in eye movement during reading: language processing, attention, vision, and oculomotor control. [11] Eye trackers bounce near infrared light off the interior of the eyeball, and monitor the reflection on the eye to determine gaze location. With this technique, the position of a fixation on a screen can be precisely determined. [12] Wang (2011) mentioned that a video-based eye-tracker which uses video cameras to record the eye position of human subjects—recording pupil dilation and eye movement—can be used to examine how fixations, saccades, and pupil dilation responses are related to the information on the screen and behavioral choices. According to Wang, [13]

understanding the relationship between these observables can help us to understand how human behavior in the economy can be affected by what information people acquire, where their attention is focused, what emotional state they are in, and even what brain activity they are engaged in. This is because fixations and saccades (matched with information shown on screen) indicate how people acquire information (and what they see), time lengths of fixations indicate attention, and pupil dilation responses indicate emotion, arousal, stress, pain, or cognitive load.[ citation needed ]

Saccades

Horizontal eye movement in reading. Left-to-right movement may be seen as "upstairs", and right-to-left saccades are clear. Reading VOG hor.gif
Horizontal eye movement in reading. Left-to-right movement may be seen as "upstairs", and right-to-left saccades are clear.

Skilled readers move their eyes during reading on the average of every quarter of a second. During the time that the eye is fixated, new information is brought into the processing system. Although the average fixation duration is 200–250 ms (thousandths of a second), the range is from 100 ms to over 500 ms. [14] The distance the eye moves in each saccade (or short rapid movement) is between 1 and 20 characters with the average being 7–9 characters. The saccade lasts for 20–40 ms and during this time vision is suppressed so that no new information is acquired. [15] There is considerable variability in fixations (the point at which a saccade jumps to) and saccades between readers and even for the same person reading a single passage of text. Skilled readers make regressions back to material already read about 15 percent of the time. The main difference between faster and slower readers is that the latter group consistently shows longer average fixation durations, shorter saccades, and more regressions. [16] These basic facts about eye movement have been known for almost a hundred years, but only recently have researchers begun to look at eye movement behavior as a reflection of cognitive processing during reading. [17]

A diagram demonstrating the acuity of foveal vision in reading EyeFixationsReading.gif
A diagram demonstrating the acuity of foveal vision in reading

The lower line of text simulates the acuity of vision with the relative acuity percentages. The difficulty of recognizing text increases with the distance from the fixation point. [18]

Dyslexia

People with dyslexia generally have a decreased reading speed, which can be caused by many different variables. There are many remedies to try to combat these deficits, depending on what biological theory of dyslexia they are based on. One such idea is based on magnocellular deficit, where magnocellular pathways are uncoordinated, causing the skipping or re-reading of lines. [19]

Computer models of eye movement in reading

Competition–interaction theory and SERIF emphasise low level oculomotor processes in reading such as how the word length of the currently fixated word and its neighbour words affect saccade amplitude and latency (or fixation duration). [20] [ citation needed ] Reader, EMMA, E-Z Reader and SWIFT emphasise higher level cognitive processes such as lexical processing, word frequency, word parsing or word predictability.[ citation needed ]

See also

Notes

  1. Heller (1988:39).
  2. Leonardo da Vinci (1955), das Lebensbild eines Genies, Emil Vollmer Verlag, Wiesbaden Berlin. Dokumentation der Davinci Ausstellung in Mailand 1938, p. 430; cited in 'Hans-Werner Hunziker, (2006) Im Auge des Lesers: foveale und periphere Wahrnehmung – vom Buchstabieren zur Lesefreude' [In the eye of the reader: foveal and peripheral perception – from letter recognition to the joy of reading] Transmedia Stäubli Verlag Zürich 2006 ISBN   978-3-7266-0068-6.
  3. Rayner, Pollatsek, & Alexander (2005).
  4. Lamare, M. (1893). "Des mouvements des yeux pendants la lecture". Comptes Rendus de la Société Française d'Ophthalmologie: 35–64.
  5. Delabarre (1898).
  6. Erdmann B & Dodge R (1898).
  7. Schott E (1922).
  8. Finocchio, Preston, & Fuchs (1990).
  9. Liu, Zhou, Hu (2011).
  10. Tecce, Pok, Consiglio, O'Neil (2005).
  11. "Eye Movements During Reading". Pitt.edu. Retrieved 14 April 2014.
  12. Wang 2011.
  13. Wang 2011, p. 185.
  14. Sereno & Rayner (2003).
  15. Rayner, Foorman, Perfetti, Pesetsky, & Seidenberg (2001).
  16. Rayner, Slattery, Belanger (2010).
  17. Rayner K (1975).
  18. Hans-Werner Hunziker, (2006) Im Auge des Lesers: foveale und periphere Wahrnehmung – vom Buchstabieren zur Lesefreude [In the eye of the reader: foveal and peripheral perception – from letter recognition to the joy of reading] Transmedia Stäubli Verlag Zürich 2006, ISBN   978-3-7266-0068-6.
  19. Stein J., The magnocellular theory of developmental dyslexia Dyslexia. 2001 Jan–Mar;7(1):12–36.
  20. Yang, S.-N; McConkie, G.W (2001). "Eye movements during reading: A theory of saccade initiation times". Vision Research. 41 (25–26): 3567–3585. doi: 10.1016/S0042-6989(01)00025-6 . PMID   11718796.

Related Research Articles

<span class="mw-page-title-main">Saccade</span> Eye movement

A saccade is a quick, simultaneous movement of both eyes between two or more phases of fixation in the same direction. In contrast, in smooth-pursuit movements, the eyes move smoothly instead of in jumps. The phenomenon can be associated with a shift in frequency of an emitted signal or a movement of a body part or device. Controlled cortically by the frontal eye fields (FEF), or subcortically by the superior colliculus, saccades serve as a mechanism for fixation, rapid eye movement, and the fast phase of optokinetic nystagmus. The word appears to have been coined in the 1880s by French ophthalmologist Émile Javal, who used a mirror on one side of a page to observe eye movement in silent reading, and found that it involves a succession of discontinuous individual movements.

Saccadic masking, also known as (visual) saccadic suppression, is the phenomenon in visual perception where the brain selectively blocks visual processing during eye movements in such a way that neither the motion of the eye nor the gap in visual perception is noticeable to the viewer.

<span class="mw-page-title-main">Vision span</span> Arc of accurate visual perception

Vision span or perceptual span is a controversial concept referring to the angular span, within which the human eye has sharp enough vision to perform an action accurately. 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 macula, where there is a higher density of cone cells. The macula has a diameter of about 16 degrees of the retina. The field of view that is observed with sufficient resolution to read text typically spans about 6 degrees of arc, which is wide enough to allow a clear view of about five words in a row when printed text at ordinary size is held about 50 centimeters from the eyes. Regarding face processing, the field of view with a sufficient amount of information in order to recognise faces accurately spans about 7° which represents about 45% of a face. The brain creates the illusion of having a greater visual span by automatically and unconsciously moving the center of vision into any area of interest in the field of view.

<span class="mw-page-title-main">Eye tracking</span> Measuring the point of gaze or motion of an eye relative to the head

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 psycholinguistics, marketing, as an input device for human-computer interaction, and in product design. In addition, eye trackers are increasingly being used for assistive and rehabilitative applications such as controlling wheelchairs, robotic arms, and prostheses. Recently, eye tracking has been examined as a tool for the early detection of autism spectrum disorder. There are several methods for measuring eye movement, with the most popular variant using video images to extract eye position. Other methods use search coils or are based on the electrooculogram.

<span class="mw-page-title-main">Eye movement</span> Movement of the eyes

Eye movement includes the voluntary or involuntary movement of the eyes. Eye movements are used by a number of organisms to fixate, inspect and track visual objects of interests. A special type of eye movement, rapid eye movement, occurs during REM sleep.

Microsaccades are a kind of fixational eye movement. They are small, jerk-like, involuntary eye movements, similar to miniature versions of voluntary saccades. They typically occur during prolonged visual fixation, not only in humans, but also in animals with foveal vision. Microsaccade amplitudes vary from 2 to 120 arcminutes. The first empirical evidence for their existence was provided by Robert Darwin, the father of Charles Darwin.

<span class="mw-page-title-main">Fixation (visual)</span> Maintaining ones gaze on a single location

Fixation or visual fixation is the maintaining of the gaze on a single location. An animal can exhibit visual fixation if it possess a fovea in the anatomy of their eye. The fovea is typically located at the center of the retina and is the point of clearest vision. The species in which fixational eye movement has been verified thus far include humans, primates, cats, rabbits, turtles, salamanders, and owls. Regular eye movement alternates between saccades and visual fixations, the notable exception being in smooth pursuit, controlled by a different neural substrate that appears to have developed for hunting prey. The term "fixation" can either be used to refer to the point in time and space of focus or the act of fixating. Fixation, in the act of fixating, is the point between any two saccades, during which the eyes are relatively stationary and virtually all visual input occurs. In the absence of retinal jitter, a laboratory condition known as retinal stabilization, perceptions tend to rapidly fade away. To maintain visibility, the nervous system carries out a procedure called fixational eye movement, which continuously stimulates neurons in the early visual areas of the brain responding to transient stimuli. There are three categories of fixational eye movement: microsaccades, ocular drifts, and ocular microtremor. At small amplitudes the boundaries between categories become unclear, particularly between drift and tremor.

<span class="mw-page-title-main">Eye movement in music reading</span> Role of the eyes in reading music

Eye 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. The phenomenon has been studied by researchers from a range of backgrounds, including cognitive psychology and music education. These studies have typically reflected a curiosity among performing musicians about a central process in their craft, and a hope that investigating eye movement might help in the development of more effective methods of training musicians' sight reading skills.

The eye–hand span is the distance across part of a text, usually a linguistic text that is being copied via typing or a piece of notated music that is being performed, defined as the distance between the position of the eyes acquiring that information and the hand(s) typing or performing it. Specifically, the eye–hand span is typically measured from the location of central visual input, and stretches between the syllable or chord currently being typed or performed, and the lateral location of the simultaneous fixation. This distance may be measured either in units of linear measurement or in characters or other "bits" of data. Some authors refer to the eye–hand span as the "perceptual span" for the visual information perceivable around the region of center of vision used in reading, and in some cases including peripheral input. The eye–hand span is analogous to the eye–voice span in reading language aloud and in singing.

Within computer technology, the gaze-contingency paradigm is a general term for techniques allowing a computer screen display to change in function depending on where the viewer is looking. Gaze-contingent techniques are part of the eye movement field of study in psychology.

<span class="mw-page-title-main">Louis Émile Javal</span> French ophthalmologist (1839–1907)

Louis Émile Javal was a French ophthalmologist born in Paris. Javal is remembered for his studies of physiological optics and his work involving a disorder known as strabismus.

Visual perception is the ability to interpret the surrounding environment through photopic vision, color vision, scotopic vision, and mesopic vision, using light in the visible spectrum reflected by objects in the environment. This is different from visual acuity, which refers to how clearly a person sees. A person can have problems with visual perceptual processing even if they have 20/20 vision.

<span class="mw-page-title-main">Alan Kennedy (psychologist)</span> British psychologist

Robert Alan Kennedy FRSE is emeritus professor of Psychology at the University of Dundee, and formerly research associate at the Laboratoire de Psychologie et Neurosciences Cognitives of Paris Descartes University, Boulogne-Billancourt, France. He carries out research into eye movement control in reading and the viewing of static and moving images and is the author of over 100 journal articles.

Screen reading is the act of reading a text on a computer screen, smartphone, e-book reader,

Transsaccadic memory is the neural process that allows humans to perceive their surroundings as a seamless, unified image despite rapid changes in fixation points. Transsaccadic memory is a relatively new topic of interest in the field of psychology. Conflicting views and theories have spurred several types of experiments intended to explain transsaccadic memory and the neural mechanisms involved.

Word recognition, according to Literacy Information and Communication System (LINCS) is "the ability of a reader to recognize written words correctly and virtually effortlessly". It is sometimes referred to as "isolated word recognition" because it involves a reader's ability to recognize words individually from a list without needing similar words for contextual help. LINCS continues to say that "rapid and effortless word recognition is the main component of fluent reading" and explains that these skills can be improved by "practic[ing] with flashcards, lists, and word grids".

<span class="mw-page-title-main">Parafovea</span>

Parafovea or the parafoveal belt is a region in the retina that circumscribes the fovea and is part of the macula lutea. It is circumscribed by the perifovea.

<span class="mw-page-title-main">Eye movement in scene viewing</span> Visual processing of information presented in scenes

Eye movement in scene viewing refers to the visual processing of information presented in scenes. This phenomenon has been studied in a range of areas such as cognitive psychology and psychophysics, where eye movement can be monitored under experimental conditions. A core aspect in these studies is the division of eye movements into saccades, the rapid movement of the eyes, and fixations, the focus of the eyes on a point. There are several factors which influence eye movement in scene viewing, both the task and knowledge of the viewer, and the properties of the image being viewed. The study of eye movement in scene viewing helps to understand visual processing in more natural environments.

<span class="mw-page-title-main">Paris in the the Spring</span> Informal psychological test

Paris in the the Spring is a phrase often used in an informal psychological test. The phrase "Paris in the the Spring" is written with an extra "the". A subject is asked to read the text, and will often jump to conclusions and fail to notice the extra "the", especially when there is a line break between the two thes.

Silent reading is reading done silently, or without speaking the words being read.

References