The launch-site effect in reading concerns how the location where an eye movement begins influences the position where the eye lands on an upcoming printed word. Launch site is the preceding fixation; landing site is the next fixation. Classic eye-tracking research found systematic changes in mean landing position and variability as launch distance changed, consistent with models of saccadic range error. These effects help explain visual word recognition and the need for occasional corrective fixations.
Did you know that two readers can aim to recognise the same word but land at different positions partly because they started from different places? A longer eye movement can show systematic undershooting under certain reading conditions. That difference does not prove one person knows less vocabulary. The eyes are a movement system as well as a language-reading tool, so accurate word recognition emerges from coordination among visual evidence, spelling familiarity and oculomotor control.
This guide explains McConkie, Kerr, Reddix and Zola’s 1988 study of 66 college readers, systematic range error, random landing variability, functional targets and how launch site relates to preferred viewing location, optimal viewing position and refixation probability. It also explores mislocated fixations, line returns and applications for Primary and Secondary English, Mathematics, Science, History, General Paper and translation, with research conclusions kept separate from illustrative classroom examples.
Research note: No eye-tracking experiment or numerical landing measurement was performed for this article. All diagrams and school scenarios are teaching illustrations, not claims about real pupils.
Contents: where the eyes begin can change where they arrive
Open 57 chapters, mechanism comparisons and practical applications
- 1. An eye movement begins somewhere
- 2. Why vocabulary recognition depends on the landing
- 3. The launch site and landing site are different
- 4. The target word lies ahead
- 5. McConkie and colleagues’ landmark 1988 research
- 6. The functional target is not the observed point
- 7. Saccadic range error can cause undershoot
- 8. A farther launch can shift landing leftward
- 9. A closer launch changes the geometry
- 10. A launch-site diagram must identify direction
- 11. Landing positions form a distribution
- 12. Random variability remains after controlling distance
- 13. Greater movement distance can increase variability
- 14. Longer preceding fixations can alter range error
- 15. Visual information contributes to targeting
- 16. The perceptual span constrains available guidance
- 17. Preferred viewing location is an observed tendency
- 18. Optimal viewing position is a separate question
- 19. A left-of-centre landing is not automatically wrong
- 20. Refixation is one possible consequence
- 21. The 1989 refixation curve is not the launch-site curve
- 22. Some refixations are corrective movements
- 23. Nuthmann and colleagues’ modelling
- 24. Range error and random error are not synonyms
- 25. An overshoot is also possible
- 26. Skipping may arise from targeting and word knowledge
- 27. Short words provide a different motor challenge
- 28. Long words have another pattern of risk
- 29. Word length is not the sole predictor of landing
- 30. Word frequency can change processing without controlling all movements
- 31. Predictability can affect where the eye goes
- 32. The next saccade has to be planned in time
- 33. The eye–mind assumption has limits
- 34. An eye tracker gives coordinates, not intentions
- 35. Calibration error can imitate a landing shift
- 36. A line return is a special movement
- 37. Research on return sweeps adds nuance
- 38. Mirrored and inverted text change geometry
- 39. Writing direction is not universal
- 40. Text layout can change movement planning
- 41. A launch-site comparison should control target properties
- 42. The observed average can hide individual paths
- 43. An illustrative near-versus-far diagram
- 44. A hypothetical distance table is not research
- 45. Primary English: students need complete forms
- 46. Primary English: short operators need checking
- 47. Secondary English: a long word may invite a second glance
- 48. Secondary English: visual errors can hide in fluent reading
- 49. Mathematics: symbols require exact identification
- 50. Science: technical names are not visual guesses
- 51. History: names and dates deserve a deliberate look
- 52. General Paper: lexical ease is not evidence
- 53. Translation: visual targeting varies across scripts
- 54. Professional notices: one character can matter
- 55. A six-column research audit
- 56. The difference between error and uncertainty
- 57. The final lesson: vision, language and movement cooperate
Quick Test: four related positions and errors
| Concept | What it means | What must not be assumed |
|---|---|---|
| Launch site | The fixation position before the saccade | It is the same as the destination |
| Functional target | Where the movement is modelled as aiming | The tracker observes this intention directly |
| Landing site | Where the eye actually arrives | Every movement lands exactly at the intended target |
| Saccadic range error | Systematic deviation associated with planned movement distance | All movements undershoot by one universal amount |
| Random targeting variability | Unpredictable variation around a distribution | Every difference is a conscious vocabulary decision |
These are analytic terms for a model of eye movement, not judgements of personal effort. The empirical claim requires many measured trials and clear coordinate conventions.
1. An eye movement begins somewhere
The launch site is the location of the eye fixation from which a saccade starts. During reading, that starting location helps predict where the eye will land on the next word. The launch-site effect refers to systematic differences in landing position associated with how far the eye begins from its intended target.
This is an oculomotor phenomenon, not a personal choice to read well or poorly. A reader can aim toward a useful position in a word yet land elsewhere because eye movements have systematic and random error. Understanding the difference helps explain why one word receives one fixation and another gets two.
2. Why vocabulary recognition depends on the landing
A word’s letter information is easier to obtain at some fixation locations than others, depending on the visual and lexical properties of the target. A landing near the intended recognition-friendly region can allow efficient identification, while another landing may require a corrective movement.
Vocabulary and eye movement cooperate during fluent reading, but they are not identical. A favorable landing helps access a visible form; it does not guarantee the reader knows its scientific definition or grammatical sense. A complete education lesson must continue from visual recognition to actual meaning.
3. The launch site and landing site are different
The launch site marks where a saccade began, often in or near the preceding word. The landing site marks where the eye arrives after the movement, typically inside a target word or an adjacent region.
Researchers can measure the positions as distances in character spaces or visual angles. One should not treat the two locations as interchangeable or infer the original intention from the final landing alone. A study may need the preceding fixation to explain a target’s placement.
4. The target word lies ahead
In normal left-to-right English reading, an intended target frequently lies to the right of the current fixation. The eye movement is planned according to the word’s location and available visual information.
The display can include word boundaries, length cues and context from parafoveal vision. Those data help guide saccades, but the actual movement also reflects oculomotor constraints. A word’s spelling and meaning may influence reading without uniquely determining its landing coordinate.
5. McConkie and colleagues’ landmark 1988 research
George McConkie, Paul Kerr, Michael Reddix and David Zola recorded eye movements from 66 college students who read chapters of a novel. Their 1988 Vision Research paper analysed how the locations of initial fixations depended on prior launch sites.
They reported highly structured landing distributions after grouping by starting location. The results supported principles involving functional targeting, systematic range error and random variability. The finding was a group-level observation under specific adult reading conditions, not a fixed prediction for every word or learner.
6. The functional target is not the observed point
A reader’s visual system may aim a saccade toward a useful location within a target word. The final landing can differ from that functional target because of movement error.
This distinction prevents the mistaken conclusion that the eye deliberately chose the exact place it happened to land. The observed coordinate is evidence about movement, while the hypothesised functional target belongs to a model. Both must be considered when interpreting reading behaviour.
7. Saccadic range error can cause undershoot
A systematic range error can make longer intended saccades land short of the functional target location on average. Under the range-error model, the distance from launch site to target helps explain how the distribution of landing positions shifts.
This does not mean every long saccade undershoots or that the error has one universal numeric size. The model predicts a tendency across trials, with random variability around it. A classroom drawing should be labelled conceptual rather than presented as measured coordinates.
8. A farther launch can shift landing leftward
In the classic left-to-right English findings, a more distant launch site tended to produce a systematic shift in mean landing position relative to the target, consistent with undershooting. Nuthmann, Engbert and Kliegl’s later modelling also described the shift.
The relationship requires carefully defined coordinates. A launch far from the word changes the intended saccade range, and range error affects where the eye actually lands. The effect concerns geometry and motor control rather than whether the target word is more important.
9. A closer launch changes the geometry
Starting immediately before a word requires a shorter forward eye movement than beginning several words away. The target is physically the same, but the saccade range and potential landing error differ.
A research result that ignores starting position can wrongly attribute a landing difference to target length or lexical familiarity. This is why investigators partition or statistically control launch sites. A good vocabulary researcher asks where the evidence-generating movement began.
10. A launch-site diagram must identify direction
Imagine a left-to-right sentence with the word garden as the target. Draw one hypothetical launch location near the target and another farther to its left. Indicate the intended landing region without placing empirical arrows at exact coordinates.
The diagram is an analogy for the spatial relationship. A real study would need eye-tracker data and a measured landing distribution. Students should not invent a deterministic arrow length simply because they understand that longer movements have different average errors.
11. Landing positions form a distribution
Eye movements do not land at one exact character across repeated trials. McConkie and colleagues reported that landing positions, conditioned on launch site, were strongly constrained and approximately normally distributed in their analysis.
A distribution has a centre and spread, reflecting systematic bias and variability. The average does not identify every individual event. A student reading the graph should ask which launch-distance group it represents before generalising its shape.
12. Random variability remains after controlling distance
The same starting position and target can yield somewhat different landing locations because of motor noise and other factors. A deterministic model that predicts one exact landing on each trial would be too simple.
The classic study distinguished systematic saccadic range error from nonsystematic variability. Both matter for interpreting a landing histogram. A lack of perfect repetition is expected in eye movements and is not evidence of a reader’s lack of effort.
13. Greater movement distance can increase variability
In McConkie and colleagues’ account, oculomotor variability increased with distance from launch site to the target. A farther movement can therefore affect not only average landing position but also the spread of landings.
The effect belongs to an experimental model, not a requirement that every long movement is inaccurate. Different reading tasks, layouts and individuals can affect the outcome. A clear report should separate the mean shift from changes in variability.
14. Longer preceding fixations can alter range error
The 1988 model included an observation that systematic range error was reduced somewhat for saccades following longer eye fixations under the studied conditions.
This demonstrates that movement planning and execution depend on timing as well as geometry. A researcher should not simply assume that the current word’s lexical difficulty fully explains the next landing. Several stages of reading can overlap.
15. Visual information contributes to targeting
The upcoming word’s approximate length and position can be sampled through parafoveal vision. Such information helps the reader estimate a useful landing region for the next movement.
If peripheral text information is altered, saccade targeting can change even before the word is directly fixated. The research question is not only how words are recognised but how visual evidence guides the eyes toward places where recognition can occur.
16. The perceptual span constrains available guidance
The perceptual span is the region around fixation from which readers obtain useful information for reading. The next word’s spacing and approximate length may be available even when its precise spelling is not.
Launch-site models work within that limited information environment. A very distant target may not provide all the cues needed for accurate planning. The reader cannot be assumed to see every word on the page with equal detail.
17. Preferred viewing location is an observed tendency
The preferred viewing location describes where first fixations tend to land within words during normal reading. In English, it is often slightly left of the word centre on average.
The preferred location arises from both targeting and systematic error; it need not equal the hypothesised intended landing location. The launch-site effect helps explain why observed fixations can be shifted relative to the useful target. A tendency is not a command.
18. Optimal viewing position is a separate question
The optimal viewing position concerns where fixation tends to support efficient word identification under a particular experiment. A location may be recognition-friendly even though the eye often lands somewhere else.
Thus an average preferred landing location, a functional saccade target and the best word-identification position are related but not equivalent. Students should identify the property being optimised or observed before concluding that the word’s centre is always best.
19. A left-of-centre landing is not automatically wrong
An average first landing somewhat left of a word’s centre can be common in natural reading. It does not mean readers are systematically incompetent or failing to aim.
The motor system balances planning, available information and ordinary variability. An effective reading process need not place every fixation at a mathematically ideal location. Vocabulary comprehension depends on the eventual correct recognition and interpretation.
20. Refixation is one possible consequence
If a movement lands near a word’s edge, the reader may need another fixation to gather information about letters farther from central vision. The probability of an immediate refixation can depend on that initial position.
McConkie and colleagues’ 1989 follow-up found the chance of refixating a word was lowest near the centre in their studied data. The launch-site effect can help explain how first landings occur; the later refixation measures a distinct subsequent event.
21. The 1989 refixation curve is not the launch-site curve
A graph of refixation probability against landing position answers whether an extra fixation followed. A graph of landing location against launch distance answers where the initial saccade arrived.
The curves have different variables and units. Confusing them can lead to an explanation that sounds plausible yet has the wrong dependent measure. A careful student names each axis and its denominator before interpreting a pattern.
22. Some refixations are corrective movements
A landing that misses its intended word or falls unfavourably near a boundary may be followed by a quick corrective saccade. Such a movement need not mean the reader has failed to understand the term.
Researchers studying mislocated fixations have used models of targeting error to explain patterns of short corrective movements. The finding supports caution when interpreting rapid fixations. Short does not always mean understood, and second does not always mean confused.
23. Nuthmann and colleagues’ modelling
Ansgar Nuthmann, Ralf Engbert and Reinhold Kliegl developed an approach to estimating mislocated fixations during reading. Their work linked systematic range error with short-word skipping and unwanted refixations.
The modelling helps distinguish intended targeting from actual landing and corrective movements. It is an explanation of eye-movement data under defined assumptions, not evidence that the model can diagnose vocabulary knowledge from one pupil’s gaze.
24. Range error and random error are not synonyms
Systematic range error shifts the mean landing relative to the intended target in a predictable way with movement distance. Random motor variability produces scatter around that expectation.
Both can influence one observed fixation. A model reporting only the mean ignores spread; a model reporting only variability ignores directional bias. The conceptual distinction parallels statistical measurement in Science: systematic and random components need different explanations.
25. An overshoot is also possible
Although undershooting is a common systematic tendency in certain reading saccades, individual movements can overshoot the intended location. A reader may land on a following word or beyond the expected target.
The observed event must be described rather than forced into a universal narrative of undershooting. A study should report landing distributions and potentially mislocated events. A pupil should not be judged for one unusual movement.
26. Skipping may arise from targeting and word knowledge
A word can be skipped because the visual and contextual information available makes direct fixation less necessary, or because movement variability carries the eyes beyond the intended landing. These possibilities are not mutually exclusive.
A skipping event should therefore not be interpreted automatically as fully successful recognition. Researchers combine lexical measures, launch sites and later regressions to understand the outcome. In education, check whether the student retained the word’s actual meaning.
27. Short words provide a different motor challenge
A short target occupies fewer character positions on the line. A small targeting error can place the fixation on another word rather than within the intended target.
This may affect skipping or correction rates. However, short words such as not can be conceptually decisive. A reader’s failure to land on a brief target does not establish whether the negation was processed; the sentence’s meaning must be tested separately.
28. Long words have another pattern of risk
A longer word provides a larger landing region, but one fixation near an edge may not supply adequate high-resolution information about all its letters. An additional fixation can be useful.
The same saccade range error can have different practical consequences for long and short words. Researchers should consider both word length and initial position when interpreting refixation distributions. Vocabulary understanding remains a separate question.
29. Word length is not the sole predictor of landing
The 1988 study reported that landing distributions conditioned on launch site were not simply driven by target word length in the way an unconditioned comparison might suggest.
This is a reminder about confounding variables. Word length, launch position and display geometry can correlate in natural reading. A valid interpretation examines how results change once the starting point is controlled.
30. Word frequency can change processing without controlling all movements
A frequent word may be recognised more readily than a rare word in certain experiments. But the eye still needs to move physically to an appropriate location, and a motor error can alter its landing.
A direct lexical frequency effect and a launch-site effect can coexist. Neither variable should be declared the complete cause of every fixation. Researchers can study both using designs and models matched to the question.
31. Predictability can affect where the eye goes
A sentence context may make a short upcoming word highly likely, encouraging efficient reading and sometimes skipping. The physical distance from the launch site still influences the movement.
Contextual predictability and launch geometry are separate influences on reading. A highly expected word does not abolish motor variability. A research report must explain whether the effect concerns targeting, recognition or both.
32. The next saccade has to be planned in time
Eye movements require preparation before execution. The timing of the preceding fixation can therefore influence what information is available and how accurately a target is selected.
This is another reason the eye–mind relationship is not a one-to-one time stamp. Visual, lexical and motor processes can overlap. A student observing the eye position cannot infer the exact moment a word’s dictionary meaning was retrieved.
33. The eye–mind assumption has limits
The eye–mind assumption links where readers fixate with ongoing processing. Launch-site effects highlight the physical mechanics of eye movement, which can shift landings independently of a word’s meaning.
The result warns against treating every fixation position as a deliberate expression of comprehension. A researcher must distinguish observed gaze, motor targeting and lexical interpretation. The strongest conclusion is proportional to the instrument and experimental controls.
34. An eye tracker gives coordinates, not intentions
A calibrated eye tracker can record the location and duration of fixations. It cannot directly reveal where the reader planned to land or why a particular word attracted attention.
The intended target is part of a model inferred from patterns, not a label embedded in each fixation record. A public explanation should acknowledge that uncertainty. It is methodologically careless to announce someone’s thoughts from one saccade.
35. Calibration error can imitate a landing shift
If gaze position is estimated inaccurately, the recorded landing can appear farther left or right than it truly was. Such error can affect the observed launch-to-landing relationship.
Research requires appropriate calibration checks, data-quality filters and handling of line breaks. A small systematic recording offset could create misleading conclusions. The analysis must verify the instrument before assigning the shift to human reading behaviour.
36. A line return is a special movement
At the end of a printed line, the eyes make a return sweep to the beginning of the next line. Its direction and length differ from typical intra-line word-to-word saccades.
The same geometric and motor principles can be relevant, but line-return targeting is a distinct research question. A launch-site effect measured within a line should not automatically be applied unchanged to every return sweep.
37. Research on return sweeps adds nuance
Studies of return-sweep targeting have found that the eyes may land short of the intended line-initial word and then make a corrective movement, sometimes described as an undersweep fixation.
This supports the general importance of saccade range and correction. But a line-initial undersweep is not simply the same event as a within-word refixation in the middle of a line. Researchers must preserve those distinctions.
38. Mirrored and inverted text change geometry
Experiments on reading mirrored or inverted text have examined what happens to eye-movement targeting when familiar spatial patterns are disrupted. Findings show that landing distributions and movement control depend on visual and learned reading conditions.
A 2020 Scientific Reports article discussed systematic range error and landing-position distributions during transformed-text reading. The result should not be treated as a routine classroom prescription. It is evidence about the flexibility and constraints of oculomotor control.
39. Writing direction is not universal
English usually progresses left to right, while other scripts can progress right to left or vertically. The definition of a launch-site distance and the sign of an undershoot need to follow the actual reading direction.
A cross-language comparison should report coordinates relative to the target and direction rather than saying every reader always lands left of centre. The phrase ‘leftward shift’ is meaningful only in the specified geometric convention.
40. Text layout can change movement planning
Font size, line spacing, column width and word separation change the spatial relationships among printed targets. The eyes may require different saccade lengths even when the words are identical.
A launch-site analysis needs the display geometry and target definitions. It is not valid to compare one experiment using large spaced text with another using dense tiny print without considering the physical differences. The medium is part of the measurement.
41. A launch-site comparison should control target properties
Suppose condition A contains short familiar words near the preceding fixation while condition B contains long rare words farther away. Their landings may differ for several reasons besides launch distance.
A careful experiment can match items or model lexical variables and geometry together. Simply labeling the farther condition ‘harder vocabulary’ would conflate motor and linguistic processes. Research design must separate what was manipulated from what changed incidentally.
42. The observed average can hide individual paths
Two readers may begin at different locations or make different landing errors yet produce similar mean fixation positions across a passage. Aggregation can conceal the underlying variation.
The study should report distributional features and relevant participant differences when warranted. A single average location cannot describe every saccade. A student reading an eye-tracking plot needs the axis, sample and uncertainty.
43. An illustrative near-versus-far diagram
Draw a target word and two fictional launch points: one a few character spaces before the target and another considerably farther away. Explain that a systematic range-error model predicts the mean landing distribution may shift with launch distance.
Do not draw exact numerical landing sites as if measured. The diagram demonstrates the variables. An authentic result would require actual fixation positions from many valid trials under controlled text conditions.
44. A hypothetical distance table is not research
A teacher may label the two fictional launch sites as ‘near’ and ‘far’ and ask which saccade covers the greater distance. Students can identify the larger intended movement without pretending the final landing can be computed from one simple rule.
This is a Mathematics and Science exercise in measurement definition. The published research estimates the relationship statistically. A toy example should remain clearly distinct from empirical parameters.
45. Primary English: students need complete forms
A Primary pupil may land near the beginning of a long unfamiliar word and make another fixation to inspect its final letters. That can support accurate decoding rather than signal a failure.
Teach useful spelling–sound patterns, word meaning and sentence comprehension. Avoid telling children to aim their eyes at a perfect internal position. Research does not establish that conscious eye steering is the right literacy intervention.
46. Primary English: short operators need checking
A common word such as not can be visually short and predictable while fundamentally changing an instruction. If a pupil passes it over, their final interpretation may be wrong.
Have the pupil paraphrase the complete condition and test a real example. Eye-movement location is not a substitute for comprehension. Vocabulary technology is useful when even small words retain their logical force.
47. Secondary English: a long word may invite a second glance
A Secondary learner encountering an abstract term may benefit from inspecting both its beginning and suffix. This can help distinguish it from similar-looking words and identify its grammatical role.
The teacher should then ask for a precise definition and authentic usage. A favourable landing does not guarantee semantic understanding. Good reading integrates visual recognition with concept knowledge and sentence interpretation.
48. Secondary English: visual errors can hide in fluent reading
A student may read a familiar phrase quickly and substitute an expected word for the author’s actual term. Their eyes may move smoothly while the interpretation is inaccurate.
Teach exact quotation and verification when analysing literature. The relevant skill is recovering the printed evidence, not optimising a saccade endpoint. Reading speed is valuable only when the meaning survives.
49. Mathematics: symbols require exact identification
A line of Algebra contains operators and digits whose positions determine the calculation. A small misreading can change an inequality, sign or value.
Ask pupils to verify the full expression and test boundary cases before solving. The launch-site effect describes eye movement, not mathematical validity. A clear visual sample helps, but the final solution must follow the correct symbols.
50. Science: technical names are not visual guesses
Scientific terms can share prefixes while differing in the suffix that names the process or substance. A reader may need to inspect the complete printed form to distinguish them.
Use a trusted definition and an original explanation of the phenomenon. A second fixation can be appropriate. The goal is not an unmeasured landing position but accurate scientific vocabulary and reasoning.
51. History: names and dates deserve a deliberate look
An archival document may contain visually similar names or dates. The eyes may land differently on long or short strings, but that movement cannot verify which person the document identifies.
Check exact spelling, date and provenance. A historically consequential label should never be silently corrected from a partial visual pattern. The eye’s geometry supports recognition; source criticism establishes the referent.
52. General Paper: lexical ease is not evidence
A familiar phrase may be easy to read yet express an unsupported claim. An accurate technical term may require slower inspection.
GP students should identify the actual proposition, evidence and limitations. Eye-movement mechanics do not decide whether a statement is true. Vocabulary as a technology helps when recognition supports thoughtful analysis rather than intuitive acceptance.
53. Translation: visual targeting varies across scripts
Different writing systems have different symbol structures, word boundaries and reading directions. A launch-site effect described with English character positions does not transfer unchanged to every language.
The translator should focus on complete source meaning, target-language grammar and faithful terminology. Eye-tracking research can inform interface design, but it is not a translation-quality test. Language-specific evidence remains necessary.
54. Professional notices: one character can matter
An equipment identifier or customer name may differ from another by one character. Motor accuracy and lexical recognition can both influence whether the printed item is identified without rereading.
When a decision is consequential, compare the full string against the authoritative record. A predictable eye movement does not authorise a guessed value. Good vocabulary use includes disciplined exact verification.
55. A six-column research audit
Record launch site, target boundary, intended or modelled landing location, observed landing, word length and the resulting refixation or skip status. Add the participant language, saccade direction, display properties and eye-tracking quality.
These fields let another reader distinguish motor range error, visual information and lexical processing. A paper showing only where the eyes landed leaves essential explanations unstated. Research literacy requires reconstructible variables.
56. The difference between error and uncertainty
A systematic shift in a landing distribution is not the same as an individual movement being ‘wrong’. Researchers use the term error relative to a hypothesised functional target, not as a criticism of a person’s effort.
The motor system performs under constraints and tolerates variability. The practical outcome can still be successful word recognition. A vocabulary lesson should represent the model accurately without implying that ordinary fixations are personal mistakes.
57. The final lesson: vision, language and movement cooperate
The launch-site effect shows that the previous fixation’s position can systematically influence where the next eye movement lands. It helps explain why word identification and refixations depend partly on geometry and motor control, not only on whether the word is familiar.
The educational outcome is straightforward: support accurate visual recognition, meaningful comprehension and verification of important details. A reader does not need perfect eye positioning to use vocabulary well, but does need the correct word and its intended meaning.
Full case: a near and a far launch
Imagine the target word garden in an invented sentence. Mark a launch point just before the target and another farther to its left. The longer intended saccade involves a greater movement range. A range-error model predicts that launch distance can affect the average landing distribution, but no exact landing coordinate can be deduced from this simple drawing.
The class labels the launch point, functional target and possible landing region, then asks whether the reader could still identify the correct word. The lesson explains a scientific mechanism while preserving uncertainty; it does not report eye-tracker data or a universal number of letters of undershoot.
Eight-stage research and comprehension audit
- Locate the starting fixation and the printed target in the given reading direction.
- Distinguish the hypothesised functional target from the measured landing.
- Describe the movement distance and the word boundaries.
- Consider systematic range error separately from random variability.
- Check whether a skip, refixation or correction followed the landing.
- Account for word length, spacing, preview information and display geometry.
- Read the actual source’s participant sample and measurement method before citing a trend.
- Test comprehension of the target word through a definition and original sentence, not a landing coordinate.
Frequently asked questions
1. What is the launch site?
The fixation position from which the next saccade begins.
2. What is the landing site?
The position where the eye arrives after the saccade.
3. What is the launch-site effect?
A systematic relation between starting distance and the distribution of landing positions under defined reading conditions.
4. What is saccadic range error?
A systematic tendency for actual movement range to differ from the intended range.
5. Do all long eye movements undershoot?
No. The research describes average tendencies with variability.
6. What is a functional target?
The hypothesised location toward which the oculomotor system aims.
7. Does preferred viewing location equal optimal viewing position?
Not necessarily. One is an observed landing tendency; the other a recognition-efficiency construct.
8. Can a launch site predict a refixation?
It can influence the landing position, which may affect the chance of another fixation, but prediction is probabilistic.
9. Can one unusual landing diagnose a learning disorder?
No. Eye-movement variability and broad educational evidence must be considered.
10. What is the educational goal?
Accurately recognise the full word and understand its meaning, regardless of ordinary landing variability.
Research sources and connected eduKate vocabulary guides
- McConkie, Kerr, Reddix and Zola (1988): Eye Movement Control During Reading I — Initial Fixation Locations — 66-reader study and range-error principles.
- University of Illinois Research Record: Initial Fixation Locations — authors, method and original DOI.
- McConkie and colleagues (1989): Eye Movement Control During Reading II — Frequency of Refixating a Word — how landing locations relate to additional fixations.
- Nuthmann, Engbert and Kliegl: Self-Consistent Estimation of Mislocated Fixations During Reading — systematic and random eye-movement errors.
- Modulation of Oculomotor Control During Reading of Mirrored and Inverted Texts — landing distributions and systematic range error.
- An Eye-Movement Exploration into Return-Sweep Targeting During Reading — a distinct type of long saccade and corrective movement.
- Reichle and colleagues (1998): Toward a Model of Eye Movement Control in Reading — lexical and oculomotor modelling.
- Vocabulary | What Is the Optimal Viewing Position? — identification efficiency versus actual landing.
- Vocabulary | What Is Refixation Probability? — what may happen after the landing.
- Vocabulary | What Is the Eye–Mind Assumption? — why gaze is not a direct transcript of thought.
- Vocabulary Learning Hub — further word recognition and reading studies.
The launch-site effect shows why eye movements must be understood as physical actions coordinated with visual word recognition. Where the eye starts can alter where it lands, but the resulting position does not by itself reveal meaning or ability. Vocabulary becomes useful when accurate visual identification is followed by a defensible interpretation of the actual text.