Critical Flicker Fusion Research Articles

Eyestrains among smartphone users while watching videos in Taipei MRT carriages: a comparison between sitting and standing postures

In MRT carriages, more passengers are watching videos on their smartphones during daily commutes, yet the impact of these viewing conditions on visual strain remains unexplored. This study examined eyestrain in 24 male and 24 female participants while watching videos on smartphones in two postures (sitting and standing) and over two durations (15 min and 30 min) in Taipei MRT carriages. We measured critical flicker fusion frequency (CFF) reduction, visual fatigue scale (VFS) scores, and viewing distance (VD) for each trial. Results revealed significant effects of sex, posture, and viewing duration on visual strain, with notable two-way interactions (sex × posture and posture × time) influencing most outcomes. Women showed greater CFF reduction while sitting compared to standing (3.47 Hz vs. 1.90 Hz, p < 0.001) and maintained shorter VDs while seated (25.5 cm vs. 34.3 cm, p < 0.001). However, they reported higher VFS scores when standing (8.94 vs. 4.60, p < 0.001), indicating increased discomfort while standing in the moving MRT carriage. Men exhibited higher CFF reduction (2.81 Hz) than women while standing (1.90 Hz) (p < 0.01), but this difference was not observed while sitting. Eyestrain indicators significantly worsened after 30 min of viewing compared to 15 min, with stronger effects on VFS scores and VDs. This finding supports the recommendation to take breaks after 20 min of smartphone use, even in MRT carriages. Although subjective eyestrain is not always recognized, watching videos on smartphones while seated can result in unexpectedly high levels of objective visual fatigue, indicated by CFF reduction. Our findings suggest that eyestrain patterns in MRT carriages differ from those reported in previous studies. Seated passengers, particularly females with shorter VD, may experience unrecognized eyestrain that could impact eye health, while standing passengers may face greater discomfort. These results highlight the need for increased awareness and preventive measures to mitigate eyestrain in digital public transportation environments.

Effect of supplementation with lutein, zeaxanthin, and omega-3 fatty acids on macular pigment and visual function in young adults with long-term use of digital devices: study protocol for a randomized double-blind placebo-controlled study

BackgroundGrowing evidence emphasizes the importance of xanthophyll carotenoids and omega-3 fatty acids in eye health. However, the beneficial effects of such supplementation have not been thoroughly discussed among adults with high screen exposure. Current trial evidence on lutein bioavailability is contradictory, and the interactions of dietary intervention with host-related factors remain elusive. This study aims to investigate the comparative effectiveness of supplementation with macular xanthophylls and omega-3 fatty acids on macular pigment optical density (MPOD) and visual function, access the bioavailability of free lutein and lutein ester, and explore the complex interplay between genetic variations, intestinal microbiota, and the dietary intervention in Chinese adults with long-term exposure to digital devices.MethodsThe Lutein, Zeaxanthin, and Omega-3 (LZO) clinical trial is a 24-week multicenter, randomized, double-blind, placebo-controlled trial of 600 participants recruited from research centers, universities, and communities. Individuals are eligible to participate if they are aged over 18 years and use digital devices for over 8 h daily in the last 2 years, and will be randomized to six arms. A total of three visits will be scheduled at baseline, 12 and 24 weeks. The primary outcome is the change in MPOD over the 24-week intervention. The secondary outcomes are changes in visual function (visual acuity, best-corrected visual acuity, contrast and glare sensitivity, critical flicker fusion, reaction time, visuognosis persistence, symptoms and signs of dry eye, retinal thickness, and optical quality), and changes in serum lutein and zeaxanthin concentrations, and erythrocyte membrane omega-3 fatty acids. Genetic variations will be determined using genome-wide genotyping at baseline. 16S rRNA gene sequencing will be utilized to assess microbiome compositional changes before and after intervention.DiscussionThe trial is anticipated to establish early interventions to prevent photochemical ocular damage and delay the onset of vision impairment in young adults with long-term repeated exposure to screen-based electronic devices, and provide valuable insights for the development of precision nutrition strategies for maintaining eye health.Clinical trial registrationwww.clinicaltrials.in.th, Identifier, TCTR20220904002.

Cystatin C: its correlation with some markers of immune system, inflammation, and its role in progression of diabetic retinopathy in type 2 diabetes

Aim: To study the correlations between Cystatin C (Cys-C) level and values of the markers of immune system and inflammation, and clinical manifestations of diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (DM).Material and Methods. 3 groups of patients with type 2 diabetes and different stages of diabetic retinopathy were formed (21 people in each). Group I – with nonproliferative diabetic retinopathy (NPDR), Group II – with pre-proliferative diabetic retinopathy (PPDR), Group III – with proliferative diabetic retinopathy (PDR). The comparison group included patients with type 2 diabetes without vascular complications. Clinical study included: visometry, tonometry, assessing critical flicker fusion frequency, biomicroscopy of the anterior segment of the eye, ophthalmoscopy, biomicroscopy and ultrasound of the retina, crystalline lens, vitreous body, photographic recording of the fundus, optical coherence tomography. The content of Cystatin C (Cys-C), soluble forms of molecules B7.2 (CD86), 4-1BB, CTLA-4, Tim-3, LAG-3, PD-1, PD-L1, Galectin-9, proteins sICAM-1, SAA, NGAL and enzymes (MPO, MMP-2, MMP-9) was examined in the blood serum with the use of multiplex analysis.Results. As DR progresses, the level of Cys-C increases and becomes higher than in individuals with diabetes: with NPDR higher by 94.1% (p &lt; 0.001), with PPDR – higher by 293.6% (p &lt; 0.001). In individuals with PDR, the concentration of Cys-C is maximum. With DR, the amount of PD-1, PD-1L, NGAL, ICAM-1, MMP-9, and MPO increases in the blood serum; as the severity of DR worsens, the levels of ICAM-1, MPO, and MMP-9 increase. Direct correlations were found between the Cys-C values, on the one hand, and the values of some studied indicators, on the other.Conclusions. In type 2 diabetes and DR, the amount of Cys-C in the blood serum increases relative to individuals with diabetes without microangiopathy; in groups with worsening severity of ophthalmopathy, an increase in Cys-C concentration was recorded with a statistically significant difference between the groups. In groups with DR, the level of ICAM-1, MMP-9, and MPO increases with increasing severity. Moderate direct correlations were found between the amount of Cys-C on the one hand and PD-1, PD-L1, as well as the noticeable ones with the values of ICAM-1, NGAL, MMP-9, MPO on the other. A direct noticeable correlation was revealed between the level of Cys-C and the values of the fundus scale.

A study protocol for a randomized controlled trial on the effect of Surya Nadi Pranayama practice on cognitive abilities in school children

Abstract Background Surya Nadi Pranayama is a yogic breathing technique that involves controlled breathing through the right nostril. The study aims to evaluate the effects of the 20-min practice of Surya Nadi pranayama (4 weeks) on cognition among schoolchildren, comparing it to observing a normal breathing pattern. Methods A randomized control study design will be adopted for this study with 100 school children with 12–16 years of age, will be recruited. Subjects will be randomly divided into the study and control groups. The study group will be advised to practice Surya Nadi Pranayama (n = 50), whereas the control group (n = 50) will be asked to relax in a sitting posture between 9 am and 10 am, Monday to Friday, for 20 min daily over 30 days. Results A baseline and post-intervention assessment will be performed for all the subjects a day before and after the intervention. The primary outcome measures are visual reaction time and auditory reaction time. The secondary outcome is critical flicker fusion frequency. Conclusion The potential benefits of this yogic breathing technique and the findings of this research may contribute to the development of interventions aimed at improving cognitive functioning in school-aged children. The study is prospectively registered in the Clinical Trial Registry of India (CTRI/2024/05/067441).

Individual peak alpha frequency correlates with visual temporal resolution, but only under specific task conditions.

The study of alpha band oscillations in the brain is a popular topic in cognitive neuroscience. A fair amount of research in recent years has focused on the potential role these oscillations may play in the discrete sampling of continuous sensory information. In particular, the question of whether or not peak frequency in the alpha band is linked with the temporal resolution of visual perception is a topic of ongoing debate. Some studies have reported a correlation between the two, whereas others were unable to observe a link. It is unclear whether these conflicting findings are due to differing methodologies and/or low statistical power, or due to the absence of a true relationship. Replication studies are needed to gain better insight into this matter. In the current study, we replicated an experiment published in a 2015 paper by Samaha and Postle. Additionally, we expanded on this study by adding an extra behavioural task, the critical flicker fusion task, to investigate if any links with peak alpha frequency are generalizable across multiple measures for visual temporal resolution. We succeeded in replicating some, but not all of Samaha and Postle's findings. Our partial replication suggests that there may be a link between visual temporal resolution and peak alpha frequency. However, this relationship may be very small and only apparent for specific stimulus parameters. The correlations found in our study did not generalize to other behavioural measures for visual temporal resolution.

Predicting visual outcomes in keratoprosthesis surgery with critical flicker fusion frequency, B-scan, visual electrophysiology and endoscopy

PurposeThis study evaluates the predictive power of the critical flicker fusion frequency (CFF) test for visual outcomes in keratoprosthesis (KPro) candidates, comparing its accuracy with B-scan ultrasound, flash visual evoked...

An Arduino-Powered Device for the Study of White Perception beyond the Visual Chromatic Critical Flicker Fusion Frequency.

Arduino microcontrollers are used for a wide range of technological and biomedical applications, such as image classification, computer vision, brain-computer interaction and vision experiments. Here, we present a new cost-effective mini-device based on RGB LED flicker stimulation for the assessment of the chromatic temporal resolution of the visual function based on the concept of critical flicker fusion frequency (CFF). The assembly of the device and its testing in thirty young subjects demonstrate the steady white visual perception of a trichromatic flicker stimulus (mixture of red, green and blue stimuli) beyond the CFF. Macular function as measured by photo-stress recovery time (PRT) was found to be independent of the CFF measurements for red, green and blue lights. However, a statistical correlation was found between the contrast modulation for CFF for red and green stimuli and PRT. Finally, wavefront measurements demonstrate that high-order aberrations improve the temporal resolution of the visual function.

PBDB-T/Pentacene-Based Organic Optoelectronic Synaptic Transistor with Adjustable Critical Flicker Fusion Frequency for Dynamic Vision.

In the era of the Internet of Things and the rapid progress of artificial intelligence, there is a growing demand for advanced dynamic vision systems. Vision systems are no longer confined to static object detection and recognition, as the detection and recognition of moving objects are becoming increasingly important. To meet the requirements for more precise and efficient dynamic vision, the development of adaptive multimodal motion detection devices becomes imperative. Inspired by the varied response rates in biological vision, we introduce the concept of critical flicker fusion frequency (cFFF) and develop an organic optoelectronic synaptic transistor with adjustable cFFF. In situ Kelvin probe force microscopy analysis reveals that light signal recognition in this device originates from charge transfer in the poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene)-co-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)-benzo[1,2-c:4,5-c']dithiophene-4,8-dione)] (PBDB-T)/pentacene heterojunction, which can be effectively modulated by gate voltage. Building upon this, we implement different cFFF within a single device to facilitate the detection and recognition of objects moving at different speeds. This approach allows for resource allocation during dynamic detection, resulting in a reduction in power consumption. Our research holds great potential for enhancing the capabilities of dynamic visual systems.

The speed of sight: Individual variation in critical flicker fusion thresholds.

The critical flicker fusion threshold is a psychophysical measure commonly used to quantify visual temporal resolution; the fastest rate at which a visual system can discriminate visual signals. Critical flicker fusion thresholds vary substantially among species, reflecting different ecological niches and demands. However, it is unclear how much variation exists in flicker fusion thresholds between healthy individuals of the same species, or how stable this attribute is over time within individuals. In this study, we assessed both inter- and intra-individual variation in critical flicker fusion thresholds in a cohort of healthy human participants within a specific age range, using two common psychophysical methods and three different measurements during each session. The resulting thresholds for each method were highly correlated. We found a between-participant maximum difference of roughly 30 Hz in flicker fusion thresholds and we estimated a 95% prediction interval of 21 Hz. We used random-effects models to compare between- and within-participant variance and found that approximately 80% of variance was due to between-individual differences, and about 10% of the variance originated from within-individual differences over three sessions. Within-individual thresholds did not differ significantly between the three sessions in males, but did in females (P<0.001 for two methods and P<0.05 for one method), indicating that critical flicker fusion thresholds may be more variable in females than in males.

Transcranial Direct Current Stimulation Combined With Aerobic Exercise for the Treatment of Chronic Nonspecific Low Back Pain

Objective: The purpose of the study is to determine the effectiveness of transcranial direct current stimulation (tDCS) combined with aerobic exercise in the short, medium, and long term. Methods: Two-arms triple-blind randomized controlled trial. Thirty-eight subjects with a diagnosis of nonspecific chronic low back pain. Experimental group will receive real-tDCS and aerobic exercise and control group will be treated with sham tDCS and aerobic exercise. Pain intensity, pressure pain, disability, kinesiophobia, quality of life, catastrophism, heart rate variability, and critical flicker fusion frequency will be measured before and after each session and at 3- and 6-month follow-up. Discussion and Conclusion: This study introduces the novel measurement of heart rate variability and cortical arousal to explore their potential in understanding the effects of tDCS on pain modulation. Trial Registration: ClinicalTrials.gov ID NCT05830851. Date of registration: April 14, 2023.

Critical flicker fusion in patients with epilepsy under antiseizure medication.

Critical flicker frequency (CFF) and flicker frequency (FF) are used as indicators for the neurotoxic adverse events of drugs in pharmacology. In this pilot study, we investigated whether patients with epilepsy (PWE) treated with various antiseizure medications (ASM) had significantly different CFFs compared with healthy controls. In addition, we investigated the appropriateness of CFF as an objective measurement tool in PWE who reported adverse events according to the adverse event profile (AEP). Patients receiving regular antiseizure treatment at our center, along with healthy controls, were included in this study. Clinical neurotoxic symptoms, AEP scores, and serum ASM levels were assessed in the PWE group. We used a CFF device that produced a red-black, green-black, blue-black, or white-black flicker. CFF and FF were compared between PWE and healthy controls. In PWE, the correlation of alterations in CFF and FF with AEP results and through ASM serum concentrations was calculated. A total of 33 PWE and 20 healthy controls participated in the study. Except for two light modalities, CFF and FF were significantly reduced in PWE compared with controls. CFF and FF did not differ significantly between PWE with AEP scores >44 points and those with lower scores. CFF and FF levels did not correlate with changes in AEP scores, serum concentrations, or doses. CFF and FF distinguished PWE with ASM from healthy controls. No clinically relevant differentiation was detected in the heterogenous PWE group. To investigate whether CFF and FF may serve as subtle indicators of neurotoxicity or specific modes of action, additional studies are needed in more homogenous PWE groups.

Unconscious and Conscious Gaze-Triggered Attentional Orienting: Distinguishing Innate and Acquired Components of Social Attention in Children and Adults with Autistic Traits and Autism Spectrum Disorders.

Typically developing (TD) individuals can readily orient attention according to others' eye-gaze direction, an ability known as social attention, which involves both innate and acquired components. To distinguish between these two components, we used a critical flicker fusion technique to render gaze cues invisible to participants, thereby largely reducing influences from consciously acquired strategies. Results revealed that both visible and invisible gaze cues could trigger attentional orienting in TD adults (aged 20 to 30 years) and children (aged 6 to 12 years). Intriguingly, only the ability to involuntarily respond to invisible gaze cues was negatively correlated with autistic traits among all TD participants. This ability was substantially impaired in adults with autism spectrum disorder (ASD) and in children with high autistic traits. No such association or reduction was observed with visible gaze cues. These findings provide compelling evidence for the functional demarcation of conscious and unconscious gaze-triggered attentional orienting that emerges early in life and develops into adulthood, shedding new light on the differentiation of the innate and acquired aspects of social attention. Moreover, they contribute to a comprehensive understanding of social endophenotypes of ASD.

Effect of estradiol with or without micronized progesterone on cholinergic-related cognitive performance in postmenopausal women.

Women are at a higher risk of developing Alzheimer's disease (AD), and the decline in estrogens post-menopause is thought of as a factor increasing this risk. Estradiol (E2) is important in supporting cholinergic neuronal integrity, and cholinergic functioning may be negatively impacted following the loss of E2 post-menopause. The use of exogenous E2 has been observed to enhance cholinergically mediated cognitive performance in healthy post-menopausal women, which indicates a potentially protective mechanism. However, E2 is often co-administered with progestin or progesterone to prevent endometrial proliferation. Progesterone/progestins have previously been shown to have a detrimental effect on E2-mediated biological and cognitive effects mediated by cholinergic systems in preclinical models, therefore the present study aimed to assess whether progesterone would modify the effect of E2 to influence cognition during cholinergic blockade. Twenty participants completed 3-months of oral E2 treatment with micronized progesterone (mPRO) or with placebo (PLC) in a repeated-measures within-subjects crossover design, in which they also completed five anticholinergic challenge days per hormone treatment condition. During the challenge participants were administered low or high doses of the nicotinic cholinergic antagonist mecamylamine, the muscarinic cholinergic antagonist scopolamine, or placebo. Following drug administration participants performed cognitive tests sensitive to cholinergic tone, assessing attention, episodic memory, and working memory. Significant decrements were found on some tasks when participants were taking E2+mPRO compared to E2 alone. Specifically, under more challenging task conditions and larger anticholinergic doses, participants showed poorer performance on the Critical Flicker Fusion task and the Stroop test and responded more conservatively on the N-back working memory task. Other tasks showed no differences between treatments under cholinergic blockade. The findings show that mPRO when taken in concert with E2, was detrimental to effortful cognitive performance, in the presence of cholinergic blockade. These results are important for assessing the impact of combined postmenopausal hormone treatment on cognitive performance that is dependent on cholinergic functioning after menopause.

Critical flicker fusion frequency results during oxygen decompression in standard HBOT session - observational study.

Most hyperbaric medicine reports concentrate on the patient and his morbidities. In addition to the well-known indications for hyperbaric oxygen therapy (HBOT), we cannot discount possible side effects. Among medical staff regularly exposed to hyperbaric conditions the best described so far is decompression sickness. A non-invasive and easily available way to assess cognitive functioning involves the use of the critical flicker fusion frequency (CFFF) test. In the current study, the flicker test was performed several times on 21 subjects, both under normobaric and hyperbaric conditions. The test was conducted using the device that flickering was programmed according to the method of limits. While in the hyperbaric chamber, 15 of the participants breathed oxygen to reduce the risk of decompression sickness. Flicker and fusion frequencies differed from each other in both normo- and hyperbaric conditions (p < 0.01). CFFF results were dependent on oxygen breathing during decompression.

Efficacy of psychometric hepatic encephalopathy score versus critical flicker fusion frequency in diagnosing subclinical uremic encephalopathy in patients with chronic kidney disease – A pilot study

Background: Cognitive dysfunction can occur in a significant proportion of patients with chronic kidney disease (CKD). Subclinical uremic encephalopathy (SUE) is defined as cognitive impairment (CI) greater than expected for normal aging and educational level. SUE is characterized by declining cognitive function that becomes irreversible if left untreated. However, there is no specific test to confirm the diagnosis of SUE. Aim and Objectives: To determine the diagnostic accuracy of psychometric hepatic encephalopathy score (PHES) and critical flicker fusion frequency (CFFF) tests in SUE in CKD Stage 5 patients and to estimate the prevalence of CI among CKD patients. Materials and Methods: It was a cross-sectional study conducted at a tertiary care center in Chennai, South India, during September 2022–October 2022, among 35 patients diagnosed with CKD Stage 5. All patients were subjected to MMSE (Mini-mental state examination), PHES test, and CFFF test consecutively and their scores were recorded. The collected data were analyzed with IBM SPSS Statistics for Windows, Version 29.0. The scores of PHES and CFFF were compared against MMSE and their diagnostic accuracy was tested using the receiver operating characteristics curve (ROC) along with sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy, and P &lt; 0.05 was considered statistically significant. Results: Of all 35 patients, 19 (54%) were males with a median age of 60 years. Fifteen patients (43%) were on hemodialysis. The prevalence of CI among CKD patients was 60%. CI was detected with MMSE in 21 patients (60%). Out of the 21 patients, 18 were positive with PHES (P &lt; 0.01) and 19 were positive with CFFF (P &lt; 0.05). PHES showed better sensitivity (90.9%), specificity (90.0%), PPV (90.9%), and NPV (90.0%) than CFFF, which showed a sensitivity of (89.7%), specificity (85.3%), PPV (86.8%), and NPV (87.5%). PHES was more accurate (accuracy – 90.5%) than CFFF (85.5%). 29 (83%) patients completed MMSE and 24 (69%) patients completed PHES, whereas all patients (100%) completed CFFF test. The average time taken in minutes to complete MMSE, PHES, and CFFF was 14.68 ± 2.02, 30.11 ± 4.13, and 5.48 ± 1.44 min, respectively. Cognitive function scores did not differ significantly with the duration of CKD and between patients with CKD receiving dialysis. Conclusion: Both PHES and CFFF are effective in detecting impaired cognition and can be used as reliable tools in the diagnosis of SUE. Moreover, CFFF was less time-consuming and easier to complete, making it an ideal bedside test. The prevalence of CI among CKD patients was considerably high (60%). Hence, early detection and treatment would prevent patients from going into overt uremic encephalopathy where CI can become irreversible.

Effect of habitual breakfast skipping on information processing capacity, cortical response, and cognitive flexibility among medical collegiate- a cross-sectional study.

Breakfast replenishes glucose homeostasis and provides other micro-nutrients for the normal functioning of the body after a long night at night. Habitually skipping breakfast leads not only to metabolic disturbances but also to neurocognitive impairment. Hence, the current study wascarried out to study the effect of skipping breakfast on neurocognitive functions. A 9-item breakfast questionnaire was distributed online to students for identifying habitual breakfast skippers from non-skippers based on inclusion criteria. Random blood glucose was noted and visual and auditory reaction time, critical flicker fusion frequency, and Stroop test were assessed in both groups to assess cognition. Forty one habitual breakfast skippers who met the inclusion criteria showed increased visual reaction time, and auditory reaction time indicating cognitive impairment. A significant reduction in the Stroop test was observed among the non-skipper group when compared to the skipper group. This study suggests that skipping breakfast diminishes neurocognitive functions like problem-solving, planning, judgment, information retention, and reasoning.

Modeling the critical fliker fusion frequency in the human visual system

The temporal resolving power of the visual system is essential for the perception of the objective world. The lowest sampling rate of a sequence of images at which perception becomes fused is called the critical flicker fusion frequency. The variety of experimental data on critical frequency thresholds can be explained from a point of view of a model of the contrast sensitivity of the visual system that based on the tremor modulation signal. The model describes the dependence of critical frequency on stimulus brightness, adaptation brightness, duration, and the angular size of the stimulus. This model demonstrates that for bright stimuli with short duration and a large angular size, critical frequency values lie in the range up to 1000 Hz; the frame rate of 300-500 Hz should be considered optimal for the visual system; for small-sized angular stimuli, the critical frequency lies in the low-frequency region. Differences in the rate of flicker fusion can be explained by temporal sensitivity of magno- and parvocellular neurons.

Comment on Muth et al. Assessing Critical Flicker Fusion Frequency: Which Confounders? A Narrative Review. Medicina 2023, 59, 800.

We first want to thank the authors of the excellent review for their contributions to summarizing the confounders associated with critical flicker fusion frequency (CFFF) [...].

Internet addiction induced critical fusion frequency among young adults.

Critical flicker fusion frequency (CFF) is the frequency at which flickering light can be perceived as continuous and it is used to assess the processing of temporal vision. It is of interest to compare critical fusion frequency (CFF) in mild, moderate & severe internet users. Cross sectional observation study was done among 350 professional students. Internet addictions for around 372 professional students & internet addiction was evaluated by Young's scale of Internet Addiction questionnaire in the age group 18-25 years. CFF was measured using an in-house built LED-based CFF M1 Model instrument. A total of 372 participants (in age group 19-22 years) were recruited. Of the participants 65 % of them were mild internet addictors, 48% were moderate and 7% were severe internet adductors. Among the internet usage, the Kruskal-Wallis test showed a significant difference in internet addiction score, duration of internet usage (hours) and average Critical fusion frequency (Hz) (P<0.001). For the average critical fusion frequency (Hz), the Dwass-Steel-Critchlow-Fligner test showed significant pairwise comparisons between the following: (1) mild internet addictor's vs moderate internet addictors and (2) Mild internet addictors versus severe internet addictors (p<0.001). Critical flicker fusion frequency(CFF) as it is an easy, quick, and non-invasive technique used as a general indicator of cortical processing, visual persistence for cognitive flexibility.

Phantom array and stroboscopic effect visibility under combinations of TLM parameters

Solid-state light sources can be more prone to larger temporal light modulation (TLM) than conventional sources. TLM visibility depends on wave shape, frequency, modulation depth and duty cycle, and is affected by the sensitivity of the observer. TLM can be visible well above the critical flicker fusion frequency, when there is relative movement between the observer’s eyes and light source, lighted space or moving objects in the field of view. This human subjects experiment explored visibility of the stroboscopic effect (SE) versus the phantom array effect (PAE) with targeted tasks under 74 TLM waveforms. The results showed the SE visibility peaks between 90 Hz and 120 Hz, while the PAE visibility peaks between 500 Hz and 1000 Hz. The phantom array is visible to sensitive participants at 6000 Hz. Both effects are more visible under rectangular versus sinusoidal TLM, higher modulation, and when duty cycles are 10% or 30% versus 50%. Higher sensitivity participants, differentiated using the Leiden Visual Sensitivity Scale, rated TLM waveforms as more visible, especially those inherently harder to see. This work lays a foundation for a PAE metric and guides driver and dimmer designers toward electronic circuits that minimize the visibility of TLM in LED products.