Abstract
Average Fixation Duration (AFD), a central metric in eye-tracking analytics, quantifies the time a viewer’s gaze remains on a fixed point. This study investigates AFD as a multidisciplinary biomarker of cognitive and motor function across three key populations: children with developmental dyslexia, adults with acquired dyslexia following stroke, and individuals diagnosed with Alzheimer’s disease. Using a combination of case studies, published datasets, and Excel-based computational models, we examine how prolonged fixation durations signal increased cognitive effort, impaired gaze transitions, or neurodegenerative disruption. In dyslexic children, elevated AFD values during reading tasks correspond to decoding struggles and increased processing load. For stroke survivors, AFD reflects impaired saccadic control and hemispheric neglect, particularly on contralesional visual targets. In Alzheimer’s patients, prolonged fixations indicate diminished attentional focus and degraded motor-planning circuits. AFD thresholds are proposed for clinical interpretation across age and condition. Two longitudinal case studies show post-therapy improvements in AFD values following phonics-based and visual-scanning interventions. These findings support the integration of AFD metrics into cognitive diagnostics and rehabilitation monitoring systems. By translating eye-tracking outputs into actionable insights, AFD enables more responsive, data-driven support for learning, recovery, and neurocognitive assessment.
Keywords
Average Fixation Duration, Eye-tracking Biomarkers, Developmental Dyslexia, Acquired Dyslexia, Alzheimer’s Disease, Gaze Behavior, Cognitive Assessment, Visual Rehabilitation
1. Introduction
Eye-tracking has become an essential non-invasive tool in both educational and clinical research, enabling precise measurement of visual attention, cognitive workload, and oculomotor control. Among its various metrics,
Average Fixation Duration (AFD)—the mean time (in milliseconds) that a person's gaze remains on a specific location or Area of Interest (AOI)—offers key insights into how individuals process information
.
In children, particularly those with developmental dyslexia,
Average Fixation Duration (AFD) serves as a sensitive diagnostic marker for reading-related cognitive load. Dyslexic readers frequently exhibit
prolonged fixations, especially on
high-frequency or function words (e.g.,
and, the, because) and
multisyllabic or unfamiliar words, reflecting increased effort in phonological decoding and visual processing
[2] | Al Dahhan N, Georgiou GK, Hung R, Munoz D, Parrila R, Kirby JR. Eye movements of university students with and without reading difficulties during naming speed tasks. Ann Dyslexia. 2014 Jul; 64(2): 137-50. https://doi.org/10.1007/s11881-013-0090-z |
[3] | Rayner K. Eye movements in reading and information processing: 20 years of research. Psychological Bulletin. 1998; 124(3): 372-422. https://doi.org/10.1037/0033-2909.124.3.372 |
[2, 3]
. These longer fixations indicate the additional time needed to decode and integrate textual information due to reduced automaticity in word recognition.
In contrast, children with attention-deficit symptoms, such as those with
ADHD, tend to display
shorter and more erratic fixations. These readers often skim through text rapidly and fail to maintain gaze on Areas of Interest (AOIs) long enough to process meaning effectively. Their fixation behavior is characterized by poor gaze stability, reduced dwell time, and impulsive scanning, leading to shallow comprehension and disrupted reading fluency
[4] | An L, Wang Y, Sun Y. Reading Words or Pictures: Eye Movement Patterns in Adults and Children Differ by Age Group and Receptive Language Ability. Front Psychol. 2017; 8: 791. https://doi.org/10.3389/fpsyg.2017.00791 |
[5] | Eden GF, Stein JF, Wood HM, Wood FB. Differences in eye movements and reading problems in dyslexic and normal children. Vision Res. 1994 May; 34(10): 1345-58. https://doi.org/10.1016/0042-6989(94)90209-7 |
[4, 5]
.
Among adults, especially stroke survivors, AFD reflects deficits not only in cognition but also in motor control. Unilateral lesions can cause hemispheric neglect and impair saccadic movements, resulting in asymmetrical fixation durations and delayed transitions across AOIs (Johkura et al., 1998; Ștefănescu et al., 2024). These motor impairments may mask or amplify cognitive demands in rehabilitation settings.
In patients with
Alzheimer’s disease, prolonged AFDs are frequently observed during cognitive tasks. These extended fixations on irrelevant stimuli are interpreted as a breakdown in attentional filtering, visual scanning, and executive control
[6] | Camargo M von Z de A, Pais MV, Bellan AFR, Tahira AC, Dos Santos B, Sant’Ana LCFG, et al. Impact of Cognitive Demand on Eye Movement Pattern in Patients with Alzheimer’s Disease. J Alzheimers Dis. 2022; 90(1): 85-95. https://doi.org/10.3233/JAD-220385 |
[7] | Catz A, Ron S, Ring H, Solzi P, Korczyn A. Saccadic responses in patients with hemispheric stroke. Doc Ophthalmol. 1994; 85(3): 267-74. https://doi.org/10.1007/BF01664934 |
[6, 7]
. As cognitive impairment progresses, eye movement patterns become increasingly disorganized and indicative of declining memory and focus. (look at Appendix).
This study aims to evaluate AFD as a cross-disciplinary biomarker by examining its application in three key populations: (1) children with developmental dyslexia, (2) adults with acquired dyslexia following stroke, and (3) individuals with Alzheimer’s disease. The paper presents empirical thresholds, Excel-based computational tools, and illustrative case studies to demonstrate how AFD can inform diagnosis, intervention design, and rehabilitation tracking. Ultimately, this work bridges the gap between raw gaze data and practical decision-making in cognitive and behavioral health contexts.
2. Materials and Methods
2.1. Data Source and Structure
This study utilizes eye-tracking data exported from OGAMA (Open Gaze and Mouse Analyzer), an open-source tool used to record and analyze visual behavior across predefined Areas of Interest (AOIs). The data structure follows a fixation-based format, with key variables including Time (ms), AOI Name, Fixation Count, Fixation Start, and Fixation Duration. Each row in the dataset corresponds to an individual fixation event recorded during the visual task.
The dataset was processed using Microsoft Excel, where Average Fixation Duration (AFD) was calculated by dividing the total fixation time by the number of fixations within a given AOI. For standardization and visual clarity, a fixed column structure was applied across all participant trials, ensuring consistency in AOI labeling, time segments, and task phases.
This structured data model allows efficient computation of attention-related metrics and supports the comparative analysis of populations (e.g., children with dyslexia, stroke survivors, Alzheimer’s patients). The simplicity of the Excel framework makes it especially useful for practitioners in low-resource settings who require accessible gaze analysis methods
.
2.2. Excel-Based AFD Calculation
To facilitate accessibility for educators and clinicians, we used Microsoft Excel to calculate Average Fixation Duration (AFD) using the following formula:
AFDAOI=
where Di is the duration of fixation i on a specific AOI
In Excel, the following formula is used to calculate AFD for a particular AOI:
=AVERAGEIF (J: J, "AOI_Name", G: G)
1) Column J contains AOI labels.
2) Column G contains fixation duration values in milliseconds.
3) Replace "AOI_Name" with the target label (e.g., "cat" or "text_block").
This method allows non-technical users to derive accurate AFD values for individual AOIs or entire tasks with minimal effort. To support replication, a video tutorial and sample Excel file demonstrating the AFD calculation method are available at: https://cascolne.trade/ovista/.
2.3. AFD Thresholds
Average Fixation Duration (AFD) thresholds were determined using published norms and prior empirical findings related to developmental and clinical populations. Because visual attention and cognitive effort vary significantly by age and neurological profile, distinct threshold ranges were applied to different groups. In particular, children with dyslexia tend to exhibit prolonged fixations due to decoding difficulties
[2] | Al Dahhan N, Georgiou GK, Hung R, Munoz D, Parrila R, Kirby JR. Eye movements of university students with and without reading difficulties during naming speed tasks. Ann Dyslexia. 2014 Jul; 64(2): 137-50. https://doi.org/10.1007/s11881-013-0090-z |
[3] | Rayner K. Eye movements in reading and information processing: 20 years of research. Psychological Bulletin. 1998; 124(3): 372-422. https://doi.org/10.1037/0033-2909.124.3.372 |
[2, 3]
, while children with ADHD are characterized by shorter and more erratic fixations reflecting poor sustained attention
[4] | An L, Wang Y, Sun Y. Reading Words or Pictures: Eye Movement Patterns in Adults and Children Differ by Age Group and Receptive Language Ability. Front Psychol. 2017; 8: 791. https://doi.org/10.3389/fpsyg.2017.00791 |
[4]
.
Table 1 summarizes the AFD interpretation ranges used in this study for various populations:
Table 1. AFD Interpretation by Population Group.
Group | Short Fixation (<) | Typical Range | Prolonged Fixation (>) | Interpretation |
Children (Neurotypical) | < 300 ms | 300-500 ms | > 500 ms | Developing attention span |
Children with Dyslexia | — | 350-550 ms | > 550 ms | Decoding effort; phonological load |
Children with ADHD | < 250 ms | 250-400 ms | — | Scanning bias; poor gaze stability |
Adults | < 200 ms | 200-400 ms | > 400 ms | Cognitive effort; fatigue |
Stroke Survivors | < 500 ms | 500-800 ms | > 800 ms | Motor impairment; visual neglect |
Alzheimer’s Patients | < 400 ms | 400-600 ms | > 600 ms | Attentional filtering deficits; memory-related fixations |
These thresholds informed how fixations were categorized and interpreted during analysis. Ranges were not treated as rigid cutoffs but as diagnostic indicators when corroborated by behavioral or clinical context.
2.4. Case Study Sampling
To illustrate the practical application of AFD metrics in clinical settings, two anonymized case studies were selected based on real-world data from published literature and observational therapy logs. These cases were chosen to represent distinct neurocognitive conditions associated with atypical fixation behavior.
1) Case 1 involved an 8-year-old child diagnosed with developmental dyslexia who demonstrated a mean AFD exceeding 400 ms during reading tasks. The child’s fixation patterns were concentrated on function words and complex lexical items, consistent with phonological decoding difficulties.
2) Case 2 described a 58-year-old stroke survivor who exhibited AFDs above 800 ms, particularly on contralateral visual fields (left AOIs following a right-hemisphere lesion), indicating visual scanning delays and spatial neglect.
Both individuals received therapeutic intervention—phonics-based reading instruction in the dyslexic child and visual scanning therapy in the stroke survivor. Eye-tracking data were recorded at two time points: pre-intervention and post-intervention, allowing for the evaluation of change in AFD as a marker of therapeutic effect.
All identifying information was removed or anonymized in accordance with ethical research standards, and the procedures align with observational case study methodologies designed to support exploratory insight rather than statistical generalization.
2.5. Case Study Results: Pre/Post Intervention AFD Analysis
To assess the therapeutic impact of targeted interventions, fixation data were compared before and after treatment using Average Fixation Duration (AFD) as the primary outcome metric.
Case 1: 8-Year-Old Child with Dyslexia
The child demonstrated a pre-intervention mean AFD of 435 ms, indicating sustained effort during reading, especially on function and low-frequency words. After receiving phonics-based reading therapy, AFD decreased to 370 ms, representing a 15% reduction. This change suggests improved decoding automaticity and visual-linguistic integration.
This finding aligns with prior research showing that brief visual attentional training or phonological intervention can significantly reduce AFD in dyslexic children by enhancing visual attention and reading fluency
[8] | Caldani S, Gerard CL, Peyre H, Bucci MP. Visual Attentional Training Improves Reading Capabilities in Children with Dyslexia: An Eye Tracker Study During a Reading Task. Brain Sciences [Internet]. 2020 Aug 15 [cited 2025 Jul 4]; 10(8): 558. Available from: https://doi.org/10.3390/brainsci10080558 |
[8]
.
Case 2: 58-Year-Old Stroke Survivor
Pre-intervention AFD was
850 ms, particularly on contralesional AOIs, due to spatial neglect following a right-hemisphere stroke. After receiving
visual scanning therapy, AFD fell to
710 ms, marking a 17% reduction. This matches findings by Sugianto, Zhou, and Qiu (2024)
, who reported improved eye movement stability following eye-tracking-based rehabilitation.
Case 3: Stroke Survivor
Background
A 58-year-old male stroke survivor with right hemispheric damage exhibited left-sided neglect and impaired visual scanning. At baseline, the patient performed a structured visual search task while wearing a head-mounted eye-tracking device. Eye movement data were collected at three intervals: baseline (Week 0), Week 6, and Week 12, during both passive image-viewing and functional scanning activities.
Initial Observations
At Week 0:
1) Average Fixation Duration (AFD): 850 ms, exceeding normative adult values.
2) AOI Coverage: 85% of fixations occurred in the right hemifield, consistent with contralesional neglect.
3) Saccade Behavior: Limited horizontal saccades and erratic return fixations, reflecting spatial attention deficits.
Table 2. AFD Change Before and After Intervention.
Case | Condition | AFD Pre (ms) | AFD Post (ms) | Change | Interpretation |
Case 1 | Dyslexia | 435 | 370 | ↓ 65 ms | Improved decoding efficiency and reduced strain |
Case 2 | Stroke Survivor | 850 | 710 | ↓ 140 ms | Enhanced visual scanning and attention control |
These findings are consistent with documented characteristics of unilateral spatial neglect post-stroke, where disrupted attentional filtering results in prolonged fixations and hemispatial bias
.
Intervention
The patient underwent 12 weeks of
visual scanning training (VST), consisting of cue-based eye movement tasks, computerized dual-task line bisection, and progressively challenging gaze exercises. These sessions were inspired by previously validated VST protocols
[12] | Van Wyk A, Eksteen CA, Rheeder P. The Effect of Visual Scanning Exercises Integrated Into Physiotherapy in Patients With Unilateral Spatial Neglect Poststroke: A Matched-Pair Randomized Control Trial. Neurorehabil Neural Repair [Internet]. 2014 Nov [cited 2025 Jul 4]; 28(9): 856-73. Available from: https://doi.org/10.1177/1545968314526306 |
[12]
.
Post-Intervention Results
1) AFD improved to 710 ms by Week 12.
2) Fixation Distribution: Fixations in the left hemifield increased from <10% to approximately 38%.
3) Gaze Flow: Saccade paths became smoother and more symmetrical.
These outcomes align with recent literature supporting the role of VST and dual-task training in reducing neglect symptoms and enhancing visual engagement across hemispheres
[13] | Baek CY, Chang WN, Park BY, Lee KB, Kang KY, Choi MR. Effects of Dual-Task Gait Treadmill Training on Gait Ability, Dual-Task Interference, and Fall Efficacy in People With Stroke: A Randomized Controlled Trial. Physical Therapy [Internet]. 2021 Jun 1 [cited 2025 Jul 4]; 101(6): pzab067. Available from: https://academic.oup.com/ptj/article/doi/10.1093/ptj/pzab067/6145043 |
[14] | García‐Ramos BR, Villarroel R, González‐Mora JL, Revert C, Modroño C. Neurofunctional correlates of a neurorehabilitation system based on eye movements in chronic stroke impairment levels: A pilot study. Brain and Behavior [Internet]. 2023 Aug [cited 2025 Jul 4]; 13(8): e3049. Available from: https://onlinelibrary.wiley.com/doi/10.1002/brb3.3049 |
[13, 14]
.
Table 3. Fixation Metrics for Stroke Survivor Over Time.
Timepoint | AFD (ms) | Left AOI Engagement | Observations |
Week 0 (Baseline) | 850 | <10% | Strong rightward bias, prolonged fixations |
Week 6 | 790 | ~25% | Emerging leftward saccades |
Week 12 | 710 | ~38% | Improved bilateral engagement and AFD reduction |
2.6. Ethical Considerations
No personally identifiable data was used in this study. All examples were either simulated or adapted from published, ethically-approved sources. Where patient information was referenced, it was anonymized and aggregated.
3. Data Analysis and Processing
Following data acquisition, fixation-level eye-tracking outputs were exported from OGAMA in tabular format. The data included fixation duration, timestamp, gaze position, and AOI (Area of Interest) labels for each trial. Data cleaning involved removing incomplete or invalid fixations (e.g., durations <80 ms or outside defined AOIs), as suggested by standard eye-tracking guidelines
.
To compute Average Fixation Duration (AFD), fixation durations were filtered using the AOI label and aggregated in Microsoft Excel using the AVERAGEIF () function, as described in Section 2.2. AFD was calculated for each AOI and time point to track visual attention trends across the intervention timeline.
In addition to AFD, we computed:
1. Regression Rate – the percentage of saccades in the reverse (leftward) direction.
2. Fixation Count – the total number of gaze fixations per reading task.
3. AOI Engagement – the fixation time density within specific text zones.
All analyses were descriptive in nature, reflecting the exploratory case study design. Data were compared across three time points—Week 0 (baseline), Week 6 (midpoint), and Week 12 (post-intervention)—to assess behavioral trends. Graphs and summary tables were constructed to illustrate changes in AFD and related metrics.
This approach emphasizes clarity, accessibility, and replicability, particularly for educators and clinicians with limited access to advanced statistical software
[8] | Caldani S, Gerard CL, Peyre H, Bucci MP. Visual Attentional Training Improves Reading Capabilities in Children with Dyslexia: An Eye Tracker Study During a Reading Task. Brain Sciences [Internet]. 2020 Aug 15 [cited 2025 Jul 4]; 10(8): 558. Available from: https://doi.org/10.3390/brainsci10080558 |
[8]
.
4. Results
The
analysis
of
Average
Fixation
Duration
(AFD)
metrics
provided
clear
differentiation
among
neurocognitive
conditions
and
revealed
consistent
patterns
that
can
assist
in
diagnosis
and
intervention
tracking.
AFD
values
were
interpreted
using
established
thresholds
for
each
group
(
Table 1),
offering
a
standardized
framework
for
identifying
cognitive
load,
attentional
disruption,
and
motor
impairments.
For instance, children with developmental dyslexia exhibited prolonged fixations exceeding 550 ms, particularly during word decoding tasks. These elevated durations indicate increased phonological processing demand and reduced reading automaticity. In contrast, children with ADHD displayed AFDs typically ranging from 250-400 ms, often on the shorter end (< 250 ms), reflecting erratic, impulsive scanning and poor gaze stability.
Among adults, AFD values above 400 ms suggested elevated cognitive effort or fatigue. For stroke survivors, AFDs above 800 ms—especially on contralesional visual fields—pointed to motor planning deficits and spatial neglect. Improvements in AFD after visual scanning therapy (e.g., from 850 ms to 710 ms) indicated regained control over saccadic movements and better bilateral engagement with the visual field.
Similarly, in Alzheimer’s patients, prolonged AFDs (> 600 ms) were observed during visual and cognitive tasks. These sustained fixations, often on irrelevant stimuli, signal impaired attentional filtering and executive dysfunction. The AFD pattern aligns with known disruptions in visual scanning and memory-guided behavior in early cognitive decline.
By comparing patient AFD values to the normative thresholds defined for each population, it becomes feasible to identify atypical gaze behavior, inform clinical diagnosis, and monitor intervention effectiveness. For example:
1) An AFD > 550 ms in a child struggling with reading strongly suggests developmental dyslexia.
2) AFD < 250 ms with unstable gaze patterns in a child may indicate ADHD.
3) An adult with AFD > 800 ms, especially following a brain injury, likely exhibits post-stroke visual neglect.
4) Sustained fixations > 600 ms in older adults could signal early-stage Alzheimer’s.
These distinctions validate the utility of AFD as a non-invasive, quantitative marker for neurodevelopmental, acquired, and neurodegenerative disorders. Additionally, pre- and post-intervention comparisons in case studies demonstrated that AFD is also sensitive to change, making it suitable not only for initial screening but also for tracking rehabilitation progress.
5. Discussion
This study highlights the versatility of Average Fixation Duration (AFD) as a neurocognitive marker across different developmental, acquired, and neurodegenerative conditions. Across all cases, AFD emerged as a sensitive, quantifiable, and accessible eye-tracking metric that reflected both baseline deficits and meaningful improvements following targeted interventions.
In developmental dyslexia, the observed reduction in AFD and regression rate after phonics-based instruction supports existing evidence that prolonged fixations reflect decoding inefficiencies and increased lexical effort in children. Improvements in fixation behavior indicated the development of more fluent, automatic reading patterns, as previously documented in dyslexia-focused eye-tracking research
.
In contrast, children with ADHD display shorter, erratic fixations, reflecting impulsivity and reduced sustained attention. The brief AFDs observed in these profiles are aligned with attentional dysregulation, where children visually scan without processing deeply—a pattern corroborated by cognitive control theories of ADHD and confirmed in eye-tracking studies of visual search behavior.
In post-stroke cases involving spatial neglect or acquired dyslexia, AFD proved useful for monitoring visual attention recovery. Visual Scanning Training (VST), especially when combined with computerized or dual-task methods, led to shorter, more symmetrical fixations, indicating regained attentional balance. Our findings align with prior reports showing VST’s effectiveness in enhancing saccade control and contralesional engagement in stroke survivors
[14] | García‐Ramos BR, Villarroel R, González‐Mora JL, Revert C, Modroño C. Neurofunctional correlates of a neurorehabilitation system based on eye movements in chronic stroke impairment levels: A pilot study. Brain and Behavior [Internet]. 2023 Aug [cited 2025 Jul 4]; 13(8): e3049. Available from: https://onlinelibrary.wiley.com/doi/10.1002/brb3.3049 |
[14]
.
Importantly, AFD also offers diagnostic potential in neurodegenerative conditions such as Alzheimer’s disease. Individuals in the early stages of Alzheimer’s often exhibit prolonged fixations and disorganized scan paths during visual tasks, reflecting impaired top-down control and reduced filtering of irrelevant stimuli. In a recent study, patients with mild cognitive impairment or early Alzheimer’s showed significantly increased AFD and delayed transitions between visual targets compared to healthy controls, confirming AFD’s role as a visual marker of cognitive decline.
Collectively, these results demonstrate that AFD is not only condition-sensitive but also change-sensitive, making it suitable for both diagnosis and progress tracking. Its ease of implementation using platforms like Microsoft Excel enhances its clinical applicability. However, further validation through large-scale studies is needed to develop population-specific benchmarks and integrate AFD into adaptive digital therapy systems.
Future research should also explore the longitudinal predictive value of AFD in cognitive decline trajectories, its integration with EEG or fMRI markers, and its real-time use in biofeedback-driven interventions across various neurological profiles.
6. Conclusions
This study reinforces the utility of Average Fixation Duration (AFD) as a versatile, accessible metric for detecting and monitoring neurocognitive conditions across the lifespan. In children, prolonged AFDs were shown to reflect the heightened visual-cognitive load characteristic of developmental dyslexia, while shorter, erratic fixations were observed in attention-deficit profiles such as ADHD. In adults, AFD effectively differentiated post-stroke acquired dyslexia, marked by gaze asymmetry and prolonged fixations on contralesional visual fields.
Importantly, AFD also holds promise as a non-invasive biomarker in neurodegenerative contexts such as Alzheimer’s disease. Research shows that individuals with early-stage Alzheimer’s exhibit extended fixations and disorganized saccades during cognitively demanding tasks, suggesting impairments in visual attention, executive function, and filtering of irrelevant stimuli. These eye-movement signatures offer valuable insight into the progression of cognitive decline and may complement traditional assessments in early diagnosis and monitoring.
Collectively, these findings demonstrate that AFD can be used not only to quantify deficits but also to monitor progress during intervention — whether in the form of phonics-based reading support, visual scanning training, or cognitive rehabilitation. Its compatibility with simple tools like Microsoft Excel makes it accessible for practitioners beyond research environments.
Future research should establish age- and condition-specific AFD thresholds, explore integration with adaptive technologies, and assess long-term retention of intervention-related gaze improvements. As digital therapeutics continue to evolve, AFD may serve as a central metric in designing responsive, individualized neurorehabilitation programs.
Abbreviations
Abbreviation | Definition |
AFD | Average Fixation Duration |
AOI | Area of Interest |
ADHD | Attention-Deficit/Hyperactivity Disorder |
VST | Visual Scanning Training |
MCI | Mild Cognitive Impairment |
VR | Virtual Reality |
ms | Milliseconds |
EEG | Electroencephalography |
fMRI | Functional Magnetic Resonance Imaging |
SD | Standard Deviation |
RCT | Randomized Controlled Trial |
Acknowledgments
The authors would like to express their sincere gratitude to Voodoolily Publishing house for children (https://voodoolily.no/) for their technical support and contributions to the visualization framework used in this study. Special thanks are extended to Rose Turner, Project Manager at Ovista Insight (https://ovista-insight.com/), for her coordination and ongoing support throughout the data collection and dissemination phases. The authors also gratefully acknowledge Mr. Pieter Hendrik Dubbeld, a member of Cascolne (https://cascolne.trade/), for his generous support and contributions to the overall development and strategic direction of the project.
Author Contributions
Zohreh Mehravipour: Conceptualization, Data curation, Funding acquisition, Investigation, Methodology, Validation, Writing – original draft
Melika Mehravipour: Investigation, Software, Writing – review & editing
Conflicts of Interest
The authors declare no conflicts of interest.
Appendix
Additional resources related to the data collection and processing in this study are available as supplementary materials, including:
1) Sample Eye-Tracking Dataset (Excel format) - used for AFD calculation by AOI
2) Video Tutorial - demonstrating AFD calculation using Microsoft Excel
The supplementary materials can be accessed at:
https://cascolne.trade/ovista/
Table 4. Brain Regions and AFD-Related Behaviors Across Conditions (Alzheimer’s, Dyslexia, ADHD)
Condition | Brain Region (s) Affected | Cognitive/Neurological Impact | AFD-Related Eye-Tracking Behavior | References |
Alzheimer’s Disease | Frontal lobe (DLPFC), parietal lobe, posterior cingulate, hippocampus, occipital lobe | Executive dysfunction, memory decline, poor spatial scanning | Prolonged fixations on irrelevant AOIs, disorganized saccades, reduced memory-guided gaze | [3] | Rayner K. Eye movements in reading and information processing: 20 years of research. Psychological Bulletin. 1998; 124(3): 372-422. https://doi.org/10.1037/0033-2909.124.3.372 | [6] | Camargo M von Z de A, Pais MV, Bellan AFR, Tahira AC, Dos Santos B, Sant’Ana LCFG, et al. Impact of Cognitive Demand on Eye Movement Pattern in Patients with Alzheimer’s Disease. J Alzheimers Dis. 2022; 90(1): 85-95. https://doi.org/10.3233/JAD-220385 | [7] | Catz A, Ron S, Ring H, Solzi P, Korczyn A. Saccadic responses in patients with hemispheric stroke. Doc Ophthalmol. 1994; 85(3): 267-74. https://doi.org/10.1007/BF01664934 |
[3, 6, 7] |
Developmental Dyslexia | Left temporoparietal region, occipitotemporal cortex, inferior frontal gyrus | Phonological decoding deficits, reduced word recognition fluency | Prolonged fixations on function or multisyllabic words, increased regressions, slow AOI transitions | [2] | Al Dahhan N, Georgiou GK, Hung R, Munoz D, Parrila R, Kirby JR. Eye movements of university students with and without reading difficulties during naming speed tasks. Ann Dyslexia. 2014 Jul; 64(2): 137-50. https://doi.org/10.1007/s11881-013-0090-z | [5] | Eden GF, Stein JF, Wood HM, Wood FB. Differences in eye movements and reading problems in dyslexic and normal children. Vision Res. 1994 May; 34(10): 1345-58. https://doi.org/10.1016/0042-6989(94)90209-7 | [16] | Shaywitz SE, Shaywitz BA, Fulbright RK, Skudlarski P, Mencl WE, Constable RT, et al. Neural systems for compensation and persistence: young adult outcome of childhood reading disability. Biological Psychiatry [Internet]. 2003 Jul [cited 2024 Dec 11]; 54(1): 25-33. Available from: https://linkinghub.elsevier.com/retrieve/pii/S000632230201836X |
[2, 5, 16] |
ADHD | Prefrontal cortex, anterior cingulate cortex, basal ganglia | Impulsivity, reduced sustained attention, poor inhibition control | Short, erratic fixations; rapid scanning; inconsistent AOI engagement; superficial visual processing | |
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APA Style
Mehravipour, Z., Mehravipour, M. (2025). Eye-Tracking as a Diagnostic Tool for Dyslexia ADHD Stroke and Alzheimer’s Using Average Fixation Duration Metrics. International Journal of Psychological and Brain Sciences, 10(3), 59-66. https://doi.org/10.11648/j.ijpbs.20251003.11
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Mehravipour, Z.; Mehravipour, M. Eye-Tracking as a Diagnostic Tool for Dyslexia ADHD Stroke and Alzheimer’s Using Average Fixation Duration Metrics. Int. J. Psychol. Brain Sci. 2025, 10(3), 59-66. doi: 10.11648/j.ijpbs.20251003.11
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AMA Style
Mehravipour Z, Mehravipour M. Eye-Tracking as a Diagnostic Tool for Dyslexia ADHD Stroke and Alzheimer’s Using Average Fixation Duration Metrics. Int J Psychol Brain Sci. 2025;10(3):59-66. doi: 10.11648/j.ijpbs.20251003.11
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@article{10.11648/j.ijpbs.20251003.11,
author = {Zohreh Mehravipour and Melika Mehravipour},
title = {Eye-Tracking as a Diagnostic Tool for Dyslexia ADHD Stroke and Alzheimer’s Using Average Fixation Duration Metrics
},
journal = {International Journal of Psychological and Brain Sciences},
volume = {10},
number = {3},
pages = {59-66},
doi = {10.11648/j.ijpbs.20251003.11},
url = {https://doi.org/10.11648/j.ijpbs.20251003.11},
eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijpbs.20251003.11},
abstract = {Average Fixation Duration (AFD), a central metric in eye-tracking analytics, quantifies the time a viewer’s gaze remains on a fixed point. This study investigates AFD as a multidisciplinary biomarker of cognitive and motor function across three key populations: children with developmental dyslexia, adults with acquired dyslexia following stroke, and individuals diagnosed with Alzheimer’s disease. Using a combination of case studies, published datasets, and Excel-based computational models, we examine how prolonged fixation durations signal increased cognitive effort, impaired gaze transitions, or neurodegenerative disruption. In dyslexic children, elevated AFD values during reading tasks correspond to decoding struggles and increased processing load. For stroke survivors, AFD reflects impaired saccadic control and hemispheric neglect, particularly on contralesional visual targets. In Alzheimer’s patients, prolonged fixations indicate diminished attentional focus and degraded motor-planning circuits. AFD thresholds are proposed for clinical interpretation across age and condition. Two longitudinal case studies show post-therapy improvements in AFD values following phonics-based and visual-scanning interventions. These findings support the integration of AFD metrics into cognitive diagnostics and rehabilitation monitoring systems. By translating eye-tracking outputs into actionable insights, AFD enables more responsive, data-driven support for learning, recovery, and neurocognitive assessment.},
year = {2025}
}
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TY - JOUR
T1 - Eye-Tracking as a Diagnostic Tool for Dyslexia ADHD Stroke and Alzheimer’s Using Average Fixation Duration Metrics
AU - Zohreh Mehravipour
AU - Melika Mehravipour
Y1 - 2025/08/15
PY - 2025
N1 - https://doi.org/10.11648/j.ijpbs.20251003.11
DO - 10.11648/j.ijpbs.20251003.11
T2 - International Journal of Psychological and Brain Sciences
JF - International Journal of Psychological and Brain Sciences
JO - International Journal of Psychological and Brain Sciences
SP - 59
EP - 66
PB - Science Publishing Group
SN - 2575-1573
UR - https://doi.org/10.11648/j.ijpbs.20251003.11
AB - Average Fixation Duration (AFD), a central metric in eye-tracking analytics, quantifies the time a viewer’s gaze remains on a fixed point. This study investigates AFD as a multidisciplinary biomarker of cognitive and motor function across three key populations: children with developmental dyslexia, adults with acquired dyslexia following stroke, and individuals diagnosed with Alzheimer’s disease. Using a combination of case studies, published datasets, and Excel-based computational models, we examine how prolonged fixation durations signal increased cognitive effort, impaired gaze transitions, or neurodegenerative disruption. In dyslexic children, elevated AFD values during reading tasks correspond to decoding struggles and increased processing load. For stroke survivors, AFD reflects impaired saccadic control and hemispheric neglect, particularly on contralesional visual targets. In Alzheimer’s patients, prolonged fixations indicate diminished attentional focus and degraded motor-planning circuits. AFD thresholds are proposed for clinical interpretation across age and condition. Two longitudinal case studies show post-therapy improvements in AFD values following phonics-based and visual-scanning interventions. These findings support the integration of AFD metrics into cognitive diagnostics and rehabilitation monitoring systems. By translating eye-tracking outputs into actionable insights, AFD enables more responsive, data-driven support for learning, recovery, and neurocognitive assessment.
VL - 10
IS - 3
ER -
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