Section 250 of 440
Complete canonical tutorial. This reader section contains the same teaching body as PWR-067 · Peripheral target detection. Open the Power dossier.
PWR-067 · SELF GUIDED full tutorial
Keep the centre visible, report the target sector, and count both misses and false alarms
Peripheral targets can be practised, but clutter and rarity create stubborn miss risks; this is not wider vision. The method trains a defined seated detection task. The learner fixes a central marker while a helper reveals a target or blank in a prespecified sector, answers before checking and records hits, misses and false alarms. Moving the eyes changes the task, and this does not establish safe walking or driving. A balanced sector schedule is part of the method: each side and blank state appears often enough that a preferred answer cannot masquerade as peripheral detection.
1 · Permission and limits
Know exactly what you may do
2 · Get ready
Gather what you need and check the starting conditions
What you need
- A 60 cm viewing setup: one 5 mm black fixation dot at eye level and two 6 cm square white sector cards centred 20 cm left and right of the dot. The target is a 2 cm black circle centred on an otherwise identical sector card; the blank card is plain white. A cardboard shutter lets a helper reveal the two sectors together for 750 ms without moving the centre dot.
- Two folded 24-trial state lists with eight L, eight R and eight N (no target) states. Order A: L,R,N,R,N,L,N,L,R,L,N,R,R,L,N,N,R,L,L,R,N,R,N,L. Order B: N,R,L,L,N,R,R,L,N,N,L,R,L,R,N,R,N,L,N,R,L,L,N,R. For L or R, the helper places the target at that sector and a blank opposite; for N, both sectors are blank. Any void trial is reinserted later as the same state at a concealed position.
- A helper, 750 ms timer or metronome cue, and an opaque cover over the folded list.
- A trial sheet for target sector, answer, fixation loss, hit, miss and false alarm.
Before you start
- Sit supported; do not perform while walking, balancing or near traffic.
- Fix card distance, sector angles, target size, lighting and correction.
- Practise saying “left”, “right” or “none” without looking away from centre.
- Do not use this fixture to assess new field loss; new field symptoms need eye care.
3 · The method
Follow these steps in order
- Mark centre and sectors
At 60 cm, place the fixation dot at eye level and centre the two sector cards exactly 20 cm left and right of it; mark the chair and board positions.
Why: Eccentricity—the distance from central gaze—defines the task.
Check: Positions and distance are measured and recorded.
- Learn the three answers
With eyes free, view examples of left, right and blank, then return gaze to centre.
Why: Clear labels prevent response confusion.
Check: The learner identifies all practice states.
- Lock fixation
Keep the centre marker visible throughout each brief trial; do not chase the side card with the eyes.
Why: An eye movement turns peripheral detection into direct viewing.
Check: The learner reports any fixation loss and the helper watches when possible.
- Present random target or blank
The helper follows folded Order A or B and lifts the shutter for 750 ms: target left, target right or both cards blank. The next state stays concealed until the learner has answered.
Why: Blank trials are needed to measure false alarms.
Check: Order is concealed and all three states occur.
- Answer before checking
Say left, right or none, plus confidence, while still looking at centre.
Why: Committed responses separate detection from confirmation.
Check: The answer is written before the card is shown centrally.
- Classify the result
Mark hit, miss, correct rejection or false alarm; void any trial with lost fixation.
Why: Accuracy alone hides response bias and invalid trials.
Check: Every valid trial has one classification.
- Retest a novel order
After rest or a later day, use a new random order with the same sectors and target prevalence.
Why: Novel order prevents memorising where targets appear.
Check: Target frequency and geometry match the baseline.
- Audit sector balance
After the block, count how many valid left, right and blank trials were presented and how often each answer was used. If one state is underrepresented or one answer dominates, create a balanced new order before interpreting change.
Why: Sector imbalance and a habitual left, right or none response can produce an attractive overall score without reliable target detection.
Check: Valid trial counts meet the declared sector balance and no response dominates without matching the actual target order.
4 · Worked example
See the whole method used once
Scenario
Sofia sits 60 cm from a centre dot while a helper uses left, right and blank cards at marked sectors.
Walkthrough
- They measure the two sector locations and create a concealed 24-trial order with eight blanks.
- Sofia practises the three answers, then keeps the dot visible.
- The helper reveals each card briefly and Sofia answers before checking.
- Two trials with eye movement are voided rather than counted as hits.
- They count hits, misses, false alarms and correct rejections separately and save a new order for later.
- They verify that valid trials remain balanced after two fixation-loss voids; one replacement left and one replacement blank trial are added at concealed positions.
Result
Sofia improves hits without more false alarms on the matched seated task. This is not a visual-field examination or evidence of safe hazard detection while moving. The balanced valid set supports sector-specific hit and false-alarm interpretation rather than a preferred-answer score.
5 · Right and wrong
Compare correct or safer execution with the common wrong version
| Moment | Right / safer | Wrong / riskier | Why it matters |
|---|---|---|---|
| Gaze | Keep the central marker visible and void fixation-loss trials. | Look toward the target to be sure. | Direct viewing tests a different ability. |
| Blanks | Include unpredictable blank trials. | Show a target every time. | Without blanks, false alarms and guessing bias are invisible. |
| Score | Separate hits, misses, false alarms and correct rejections. | Report one percent correct only. | The same accuracy can hide very different biases. |
| Order | Use a novel random order with fixed prevalence. | Repeat a memorised left-right sequence. | Sequence memory can mimic detection. |
| Transfer | Call it seated sector-card performance. | Infer walking, balance, driving or clinical field status. | Those contexts add movement and consequence. |
| Replacement after a void | Add a concealed trial of the same state later so sector balance is preserved. | Repeat the voided target immediately in the same place. | An immediate repeat reveals the answer and turns the replacement into a memory cue. |
6 · Common mistakes
Spot the error and apply the correction
| Mistake | Fix |
|---|---|
| Look toward the target to be sure. | Keep the central marker visible and void fixation-loss trials. |
| Show a target every time. | Include unpredictable blank trials. |
| Report one percent correct only. | Separate hits, misses, false alarms and correct rejections. |
| Repeat a memorised left-right sequence. | Use a novel random order with fixed prevalence. |
| Infer walking, balance, driving or clinical field status. | Call it seated sector-card performance. |
| A fixation-loss trial is deleted without replacing its left, right or blank state, leaving the block unbalanced. | Schedule a concealed replacement of the same state later and report both the void and the replacement. |
7 · Practice
Turn the steps into a usable skill
First session
- Mark the 60 cm chair position, fixation dot, two 20 cm sector offsets and shutter; record lighting and ordinary correction.
- With direct viewing, practise one L, R and N state and the three spoken answers.
- Run the first 12 concealed states of Order A with 750 ms reveals and no immediate repetition after a fixation loss.
- Rest, run the remaining 12 states, then insert any same-state replacements later at concealed positions.
- Count valid L, R and N presentations, correct target locations, target misses or side confusions, blank false alarms and correct rejections.
- Keep the original Order B folded for the delayed matched retest.
Repeat plan
Use one 24-trial block once or twice weekly with novel orders and the same prevalence. Progress only when hits rise without more false alarms and fixation remains valid.
Progress when
- Hits improve on new orders at the same sector.
- False alarms do not increase.
- Fixation-loss and symptom rates remain low.
Do not progress when
- Fixation cannot be maintained or observed.
- Target geometry or prevalence changes.
- The learner has new missing-field symptoms or wants to test mobility.
8 · Check the result
Measure what changed
Sensitivity and false alarms for prespecified peripheral targets by eccentricity and prevalence
How: For valid trials, hit rate = correct L or R locations divided by all target presentations; blank false-alarm rate = L or R answers on N trials divided by valid N trials. Also report left and right accuracy separately, side confusions, correct rejections, voids, replacements, 20 cm offsets, 60 cm distance and 750 ms reveal time.
Good result: On two novel orders, hit rate improves or remains high without increased false alarms or fixation loss.
This does not prove: Predeclare eccentricity, target, clutter, prevalence, sensitivity and false alarms; a reaction-time gain alone may reflect criterion shift rather than better perception.
Self-check
- Can you demonstrate “Learn the three answers”? The learner identifies all practice states.
- Can you demonstrate “Present random target or blank”? Order is concealed and all three states occur.
- Can you demonstrate “Retest a novel order”? Target frequency and geometry match the baseline.
- After voiding a fixation-loss trial, can you restore sector balance without revealing which state will be replaced next?
9 · Stop, adapt or get help
Keep the safety boundary practical
Stop and get help
- Seek urgent eye/medical care for sudden field loss, curtain-like shadow, new neurological symptoms or acute double vision.
- Stop for eye strain, nausea, headache or inability to keep the centre clear.
- Use qualified orientation/mobility or vision care for moving, driving or clinical applications.
Accessibility and adaptations
- Use larger response labels or switches; response speed is not the outcome.
- A helper may watch fixation or operate cards while following the concealed order.
- Change sector position for field accessibility only as a clearly labelled new configuration.
10 · Evidence and limits
Why these instructions are here
- primary research
Primary visual-search research shows low-prevalence targets are disproportionately missed, supporting explicit prevalence and miss reporting.
Cognitive psychology: rare items often missed in visual searches - primary research
Perceptual-learning research supports specific improvement in crowded visual tasks while leaving broad field expansion unsupported.
Two-stage perceptual learning to break visual crowding
Limits
- Predeclare eccentricity, target, clutter, prevalence, sensitivity and false alarms; a reaction-time gain alone may reflect criterion shift rather than better perception.
- Unsupported claim: Expand your visual field.
- Unsupported claim: Develop 360-degree vision.
- Unsupported claim: Never miss a hazard.
- Seated card detection does not measure a clinical visual field or safe detection during mobility, aviation or driving.
Open the complete canonical research register
- Primary empirical supportLimiting / contraryCognitive psychology: rare items often missed in visual searches
J. M. Wolfe; T. S. Horowitz; N. M. Kenner · 2005 · Primary research
- Limiting / contraryRehabilitation of visuospatial neglect by prism adaptation: effects of a mild treatment regime. A randomised controlled trial
N. Vaes; G. Nys; C. Lafosse; L. Dereymaeker; K. Oostra; D. Hemelsoet; G. Vingerhoets · 2018 · Primary research
- Primary empirical supportLimiting / contraryTwo-stage perceptual learning to break visual crowding
Z. Zhu; Z. Fan; F. Fang · 2016 · Primary research
- Limiting / contraryDissociating electrophysiological correlates of contextual and perceptual learning in a visual search task
C. C. Le Dantec; A. R. Seitz · 2020 · Primary research
- Limiting / contraryOfficial boundary contextAeronautical Information Manual, Chapter 8: Medical Facts for Pilots
Federal Aviation Administration · 2026 · Official guidance
- Limiting / contraryAcute neglect rehabilitation using repetitive prism adaptation: a randomized placebo-controlled trial
G. M. Nys; E. H. de Haan; A. Kunneman; P. L. de Kort; H. C. Dijkerman · 2008 · Primary research
Read the complete evidence interpretation on the Power dossier.
Tutorial delivery controls
Learn, adapt, troubleshoot and resume
Progress is saved only in this browser on this device.
Step-by-step learner mode
Each activity includes its success check, a nearby accessible alternative and an “I’m stuck” correction path. Alternatives preserve the target where possible; when they change the task, Titan labels them as related rather than equivalent.
Mark centre and sectors
At 60 cm, place the fixation dot at eye level and centre the two sector cards exactly 20 cm left and right of it; mark the chair and board positions.
Eccentricity—the distance from central gaze—defines the task.
Positions and distance are measured and recorded.
I’m stuck on this step
Reset: Re-read this authored instruction — “At 60 cm, place the fixation dot at eye level and centre the two sector cards exactly 20 cm left and right of it; mark the chair and board positions.” — and its success check, then attempt only this step.
Possible snag: The result from “At 60 cm, place the fixation dot at eye level and centre the two sector cards exactly 20 cm left and right of it; mark the chair and board positions.” does not yet meet this declared check: Positions and distance are measured and recorded.
Correction: Return to the start of “Mark centre and sectors”, reduce complexity or pace, and repeat only the part needed to satisfy: “Positions and distance are measured and recorded.”
Stop / get help: Seek urgent eye/medical care for sudden field loss, curtain-like shadow, new neurological symptoms or acute double vision.
Learn the three answers
With eyes free, view examples of left, right and blank, then return gaze to centre.
Clear labels prevent response confusion.
The learner identifies all practice states.
I’m stuck on this step
Reset: Re-read this authored instruction — “With eyes free, view examples of left, right and blank, then return gaze to centre.” — and its success check, then attempt only this step.
Possible snag: The result from “With eyes free, view examples of left, right and blank, then return gaze to centre.” does not yet meet this declared check: The learner identifies all practice states.
Correction: Return to the start of “Learn the three answers”, reduce complexity or pace, and repeat only the part needed to satisfy: “The learner identifies all practice states.”
Stop / get help: Seek urgent eye/medical care for sudden field loss, curtain-like shadow, new neurological symptoms or acute double vision.
Lock fixation
Keep the centre marker visible throughout each brief trial; do not chase the side card with the eyes.
An eye movement turns peripheral detection into direct viewing.
The learner reports any fixation loss and the helper watches when possible.
I’m stuck on this step
Reset: Re-read this authored instruction — “Keep the centre marker visible throughout each brief trial; do not chase the side card with the eyes.” — and its success check, then attempt only this step.
Possible snag: Look toward the target to be sure.
Correction: Keep the central marker visible and void fixation-loss trials.
Stop / get help: Seek urgent eye/medical care for sudden field loss, curtain-like shadow, new neurological symptoms or acute double vision.
Present random target or blank
The helper follows folded Order A or B and lifts the shutter for 750 ms: target left, target right or both cards blank. The next state stays concealed until the learner has answered.
Blank trials are needed to measure false alarms.
Order is concealed and all three states occur.
I’m stuck on this step
Reset: Re-read this authored instruction — “The helper follows folded Order A or B and lifts the shutter for 750 ms: target left, target right or both cards blank. The next state stays concealed until the learner has answered.” — and its success check, then attempt only this step.
Possible snag: Show a target every time.
Correction: Include unpredictable blank trials.
Possible snag: A fixation-loss trial is deleted without replacing its left, right or blank state, leaving the block unbalanced.
Correction: Schedule a concealed replacement of the same state later and report both the void and the replacement.
Stop / get help: Seek urgent eye/medical care for sudden field loss, curtain-like shadow, new neurological symptoms or acute double vision.
Answer before checking
Say left, right or none, plus confidence, while still looking at centre.
Committed responses separate detection from confirmation.
The answer is written before the card is shown centrally.
I’m stuck on this step
Reset: Re-read this authored instruction — “Say left, right or none, plus confidence, while still looking at centre.” — and its success check, then attempt only this step.
Possible snag: The result from “Say left, right or none, plus confidence, while still looking at centre.” does not yet meet this declared check: The answer is written before the card is shown centrally.
Correction: Return to the start of “Answer before checking”, reduce complexity or pace, and repeat only the part needed to satisfy: “The answer is written before the card is shown centrally.”
Stop / get help: Seek urgent eye/medical care for sudden field loss, curtain-like shadow, new neurological symptoms or acute double vision.
Classify the result
Mark hit, miss, correct rejection or false alarm; void any trial with lost fixation.
Accuracy alone hides response bias and invalid trials.
Every valid trial has one classification.
I’m stuck on this step
Reset: Re-read this authored instruction — “Mark hit, miss, correct rejection or false alarm; void any trial with lost fixation.” — and its success check, then attempt only this step.
Possible snag: Report one percent correct only.
Correction: Separate hits, misses, false alarms and correct rejections.
Stop / get help: Seek urgent eye/medical care for sudden field loss, curtain-like shadow, new neurological symptoms or acute double vision.
Retest a novel order
After rest or a later day, use a new random order with the same sectors and target prevalence.
Novel order prevents memorising where targets appear.
Target frequency and geometry match the baseline.
I’m stuck on this step
Reset: Re-read this authored instruction — “After rest or a later day, use a new random order with the same sectors and target prevalence.” — and its success check, then attempt only this step.
Possible snag: Repeat a memorised left-right sequence.
Correction: Use a novel random order with fixed prevalence.
Stop / get help: Seek urgent eye/medical care for sudden field loss, curtain-like shadow, new neurological symptoms or acute double vision.
Audit sector balance
After the block, count how many valid left, right and blank trials were presented and how often each answer was used. If one state is underrepresented or one answer dominates, create a balanced new order before interpreting change.
Sector imbalance and a habitual left, right or none response can produce an attractive overall score without reliable target detection.
Valid trial counts meet the declared sector balance and no response dominates without matching the actual target order.
I’m stuck on this step
Reset: Re-read this authored instruction — “After the block, count how many valid left, right and blank trials were presented and how often each answer was used. If one state is underrepresented or one answer dominates, create a balanced new order before interpreting change.” — and its success check, then attempt only this step.
Possible snag: Infer walking, balance, driving or clinical field status.
Correction: Call it seated sector-card performance.
Stop / get help: Seek urgent eye/medical care for sudden field loss, curtain-like shadow, new neurological symptoms or acute double vision.
Correct versus incorrect execution
These accessible process diagrams are built from the tutorial’s own right/wrong teaching. They are not anatomical illustrations and do not add technique beyond the canonical tutorial.
Keep the central marker visible and void fixation-loss trials.
Look toward the target to be sure.
Include unpredictable blank trials.
Show a target every time.
Separate hits, misses, false alarms and correct rejections.
Report one percent correct only.
Use a novel random order with fixed prevalence.
Repeat a memorised left-right sequence.
Call it seated sector-card performance.
Infer walking, balance, driving or clinical field status.
Add a concealed trial of the same state later so sector balance is preserved.
Repeat the voided target immediately in the same place.
Method-structure checklist
10 of 10 structural checks present
- Ordered, Power-specific instructions — present
- Every activity has a success check — present
- Materials or supplied records are declared — present
- Measurement or assessment rule is present — present
- Tutorial-specific troubleshooting is present — present
- Stopping or escalation boundary is present — present
- Every activity has an adjacent alternative — present
- Correct-versus-incorrect comparison is present — present
- Evidence context is bound to the Power record — present
- Planning metadata is present — present
The method-readiness band and presence checklist assess tutorial presentation and are separate from evidence quality for the underlying Power. They are automated editorial aids, not human approval.
Manual editorial sign-off: Pending. This tutorial must not display a human-approved state until an identified editor signs the exact content hash.