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Flicker fusion threshold - Wikipedia, the free encyclopedia The flicker fusion threshold (or flicker fusion rate) is a concept in the psychophysics of vision. The flicker fusion threshold varies with brightness (it is higher for brighter lights) and with location on the retina where the light falls: the rod cells have a faster response than the cone cells, so flicker can be seen in peripheral vision at higher frequencies than in foveal vision. Flicker fusion is important in all technologies for presenting moving images, nearly all of which depend on presenting a rapid succession of static images (e.g. en.wikipedia.org /wiki/Flicker_fusion   (432 words)

Fusion Entropy of fusion The Entropy of fusion of a substance represents the increase in the degree of disorder involved in the... Flicker fusion threshold The flicker fusion threshold is a concept in the vision. The heat of fusion is equal to the heat of solidification. www.brainyencyclopedia.com /topics/fusion.html   (481 words)

Flicker Fusion in CrayFish Flicker fusion was the point at which we only got one electrical response from the crayfish eye with double pulse stimulation. The point of flicker fusion of humans was tested for the three wavelengths of light on one human volunteer by pulsing the lights and changing the interval between pulses, then asking the volunteer when the twin pulses appeared as one. Fusion of LED stimulus was deemed the interval at which the human subject was unable to distinguish the double pulses as separate stimuli. faculty.uca.edu /%7Ejmurray/BIOL4425/lab/reports/finalreport/Moss_Arnold/methods.htm   (533 words)

Flicker Flicker (novel) Flicker is a novel by Theodore Roszak. Flicker (screen) Flicker on a screen such as a CRT occurs when the image on the screen is updated infrequently enough th... Northern Flicker The Northern Flicker, Colaptes auratus, is a medium-sized woodpecker. www.brainyencyclopedia.com /topics/flicker.html   (94 words)

The brain determines how you see cinema: Film and the persistence of vision - part 1 - The Current - Opinions Flicker fusion is the term used in perception studies for the fusion for that flickering light. Flicker fusion threshold is defined as the frequency at which all flicker of an intermittent light stimulus disappears. Flicker fusion is important in all technologies that present "moving images," since nearly all depend, like film, on presenting a rapid succession of static images. www.thecurrentonline.com /news/2004/04/12/Opinions/The-Brain.Determines.How.You.See.Cinema.Film.And.The.Persistence.Of.Vision.Part-660088.shtml?page=1   (972 words)

Flicker sensitivity deficits in reading disabled children: A cross-sectional analysis   (Site not responding. Last check: 2007-10-16) In this study we measured both coherent motion and critical flicker fusion thresholds to determine whether these putative measures of M-stream sensitivity could discriminate between impaired and normal readers in an adult population. The percentage of coherently moving signal dots to randomly moving noise dots was varied to the subject’s detection threshold by a staircase procedure. The flicker fusion stimulus was a 2.8 degree aperture of a split field LED display (537 nm). www.physiol.ox.ac.uk /~jbt/arvo_98.html   (259 words)

Flicker/Fusion Frequency (FLIM)   (Site not responding. Last check: 2007-10-16) In the increasing process the frequency of a flickering light is augmented until a constant light is perceived. In the decreasing process the frequency of a higher frequency light, that the respondent perceives as constant, is reduced until it is subjectively perceived as flickering. Parallel to the decrease of the flicker and fusion frequencies, corresponding changes in other performance parameters were found (memory, attention, reaction speed etc.). www.schuhfried.co.at /eng/wts/flim.htm   (481 words)

Patent 4324460: Method and apparatus for testing flicker fusion frequency In the past, apparatus for detecting the flicker fusion threshold or critical flicker fusion (CFF) frequency as it is known, included only a flickering target light, the frequency of which is adjustable. The frequency of flickering at that point is referred to herein as the incremental critical flicker fusion (ICFF) frequency. The central flickering light is varied (as in past apparatus with a single flickering light) to the point at which the person being tested observes what appears to be a continuous light. www.freepatentsonline.com /4324460.html   (3127 words)

Flicker and Fast Capture The descending critical flicker frequency is the flicker threshold, and the ascending is the fusion threshold. Furthermore, the critical flicker frequency is influenced by the rate of acceleration or deceleration used in the flicker test. Granit and Harper studied the critical flicker frequency as a function of area and contributed Equation 7, where F is still the CFF, A is the stimulus area, and c and d are constants. www.bme.unc.edu /~hope/doc/flicker/flicker.html   (3494 words)

Persistence of vision Information - TextSheet.com   (Site not responding. Last check: 2007-10-16) The frequency at which flicker becomes invisible is called the flicker fusion threshold, and is dependent on the level of illumination. It is important to distinguish between the frame rate, and the flicker rate, which are not necessarily the same. To reduce the appearance of flicker, many projectors add additional flicker periods, typically doubling the flicker rate to 48 Hz, which is less visible. www.xplosive.sferahost.com /encyclopedia/p/pe/persistence_of_vision_1.html   (645 words)

Articles - Frame rate   (Site not responding. Last check: 2007-10-16) The frame rate is related to but not identical to a physiological concept called the flicker fusion threshold or flicker fusion rate. Light that is pulsating below this rate is perceived by humans as flickering; light that is pulsating above this rate is perceived by humans as being continuous. The exact rate varies depending upon the person, their level of fatigue, the brightness of the light source, and the area of the retina that is being used to observe the light source. www.sidepoint.com /articles/Frame_rate   (848 words)

flicker --  Britannica Student Encyclopedia The flicker's sticky saliva is alkaline, perhaps to counteract the formic acid that ants secrete. If flicker is to be unobjectionable at brightness suitable for home viewing during daylight as well as evening hours, the successive illuminations of the... The classical studies based on the electroretinogram indicated that the important feature that determines fusion in the cone-dominated retina is the inhibition of the retina caused by each successive light flash, inhibition being indicated by the a-wave of the... www.britannica.com /ebi/article?tocId=9274342   (690 words)

Kolasinski Dissertation   (Site not responding. Last check: 2007-10-16) However, one aspect associated with flicker is a property of the individual: the flicker fusion frequency threshold, also known as the critical fusion frequency. Grandjean (1988) indicated that the human flicker fusion frequency threshold is a circadian bodily function which increases by day and decreases by night. Thorough investigation of the flicker fusion frequency threshold should include observations of sickness for each individual at several times during the day to address diurnal changes. kb.hitl.washington.edu /virtual-worlds/kolasinski/rol.html   (4348 words)

Critical Flicker Fusion (CFF)   (Site not responding. Last check: 2007-10-16) Subjects are required to discriminate flicker from fusion, and vice versa, in a set of four light emitting diodes arranged in a one centimetre square. The diodes are held in foveal fixation at a distance of one metre. Individual thresholds are determined by the psychophysical method of limits on four ascending (flicker to fusion) and four descending (fusion to flicker) scales (Woodworth and Schlosberg, 1958). www.surrey.ac.uk /HPRU/test_cff.html   (155 words)

Integrative and Comparative Biology: Effects of Light Adaptation on the Temporal Resolution of Deep-sea Crustaceans1   (Site not responding. Last check: 2007-10-16) The effects of light adaptation on flicker fusion frequency were examined in the photoreceptors of 13 species of deep-sea crustaceans. Temporal resolution of the eye was examined by determining the critical flicker fusion frequency (CFF) in response to square pulses of light with a constant 50% duty cycle (50:50 light:dark ratio). The response to a dim test flash that generated a 100 µ V response in the dark-adapted eye was monitored between every flickering light stimulus, and subsequent flickering stimuli were not given until the response had recovered to 100 µ V. At the brightest flickering stimuli, recovery took up to one hour. www.findarticles.com /p/articles/mi_qa4054/is_200308/ai_n9252599   (1361 words)

Lecture 19   (Site not responding. Last check: 2007-10-16) One way to demonstate persistence of vision is to wave one's hand in front of a rapidly flickering light (a "stroboscope"). This is true: beyond about 60 flahes per second (the CFF) a flickering light appears to be steadily on ("fusion"). Flicker fusion is a useful defect: light sources (120 Hz), movies (72 Hz), TV and computer displays (60 Hz) all flicker, but invisibly. ruccs.rutgers.edu /~blaser/Lecture19.html   (703 words)

The Marriage of Mind and Brain   (Site not responding. Last check: 2007-10-16) During conscious experiencing flicker fusion frequency is the mechanism whereby individual images of momentary duration fuse together into an experiential solidity of image continuity in mental space. Let us assume that flicker fusion is the mechanism that applies to the interaction of magnetic field so that stable experiential features emerge, say, when beat frequencies appear and take structured form in field space. Seeing a colour, or smelling a perfume, may be the experiential nature of the field at particular flicker fusion frequencies, and the intensity of the sensory experience, and associated emotional affect, may be determined by the intensity of the field within a particular frequency range. www.datadiwan.de /SciMedNet/library/discdocs/mind.htm   (3206 words)

Flicker fusion thresholds in control subjects and identical twins -- Murawski 15 (2): 246 -- Journal of Applied ... Flicker fusion thresholds in control subjects and identical twins -- Murawski 15 (2): 246 -- Journal of Applied Physiology Flicker fusion thresholds were investigated in 18 unrelated of fusion appeared to be confirmed in the observations on the jap.physiology.org /cgi/content/abstract/15/2/246   (114 words)

Dealing with a changing world: Time to take stock   (Site not responding. Last check: 2007-10-16) The brightness of the light flashing at a rate beyond the CFF is the same as a steady light whose intensity is equal to the average intensity of the flickering light. This is the threshold contrast for detection of flicker and its inverse in the contrast sensitivity. The critical flicker fusion frequency is the maximum frequency at which we can just detect flicker in a light that is being rapidly switched on and off. www.brad.ac.uk /acad/lifesci/optometry/resources/modules/stage1/pvp1/Temporal.html   (2434 words)

ORJ: Volume 3 Peds OBJECTIVE: To determine the flicker fusion frequency in children and adolescents with insulin-dependent diabetes mellitus (IDDM) who did not have fluorescein angiographic signs of retinopathy. OUTCOME MEASURES: Retinal flicker fusion frequency, evaluated with an automated flicker perimeter in the central 30 degrees of the visual field. Flicker perimetry is a simple, noninvasive tool that may be useful to evaluate the eye function of diabetic children. www.ophthal.org /ORJ/peds/vol3.shtml   (1178 words)

VDT Design Factors At frequencies near the CFF, the sensation of flicker depends primarily on the magnitude of the AC component. That AC component has a corresponding frequency (the CFF) at which flicker is not seen by the desired percentage of the population. To control flicker, the designer controls three factors that influence visual temporal sensitivity: the refresh rate, the phosphor (of a CRT), and the average luminance of the display. www.pc.ibm.com /ww/healthycomputing/vdc-df.html   (742 words)

Highly perceptive: Student earns national honor for learning research The research project, “Critical Flicker Fusion Threshold as a Function of Subliminal Neural Plasticity,” was presented late last year at the Academy’s 24th annual conference. Critical flicker fusion (CFF) is the lowest level of continuous flicker that is perceived as a steady source of light. The ability to resolve visual modulation, or “flicker,” is believed to be limited by the primary visual system, because even though the eye can process high rates of flicker (up to 120 hertz, or cycles per second), the visual cortex cannot. www.asu.edu /news/faculty_students/holloway_050305.htm   (517 words)

Nat' Academies Press, Chemical Ecology: The Chemistry of Biotic Interaction (1995) In lobsters, chemical gradient search reduced their normal walking speed by half, and their chemoreceptive flicker fusion rate (i.e., the stimulus pulse frequency that causes responses to fuse) is an order of magnitude lower than typical visual fusion rates. Flicker fusion to 100 ms square pulses occurs at 4 Hz for the fastest receptor cells (15). Lobster chemoreceptor cells have flicker fusion frequencies of 4 Hz and can integrate stimuli over 200 ms, closely corresponding to odor sampling behavior with 4 Hz "sniffs." Using this information, spatial odor gradients can be determined from temporal analysis of odor patches typical of turbulent dispersal. www.nap.edu /books/0309052815/html/147.html   (5686 words)

fUSION Anomaly. Fusion   (Site not responding. Last check: 2007-10-16) Fusion is the same as melting, but the term fusion is usually applied to substances such as metals that become liquid at high temperatures. The term fusion is often used as shorthand for nuclear fusion, but it is also a general term describing the merging of two or more entities into a single entity. The term "heat of fusion" describes the additional heat energy that is required to convert a solid that is already at its melting point into a liquid at the same temperature. fusionanomaly.net /fusion.html   (1171 words)

URC in Behavioural Biology [SoBS - UoB] This Ph.D.concerns human/avian differences in Critical Flicker Fusion Frequency (CFF, the frequency at which a flickering light source is perceived as continuous). Normal fluorescent lights flicker at twice the electrical supply frequency (50 Hz in Europe, 60 Hz in the USA), so birds are liable to perceive a constant flicker under such lighting. We predict that if the effects are analogous to those of stroboscopic lighting on humans, tasks involving the accurate perception of movement would be impaired, the general stress of such unnatural lighting would evoke erroneous or erratic behaviour, and there may be direct effects on mental state. www.bio.bris.ac.uk /research/behavior/welfphd.htm   (999 words)

Stuart Anstis Negative afterimages of luminance [and color] were also enhanced when projected on a test field that flickered between fl and white [or between complementary colors.] So flicker also enhances both simultaneous and successive contrast, for both luminance and color. For spatial decrements (dark spots) on white surrounds, the brightness averaging functions were strongly nonlinear winner-take-all for both binocular fusion and flicker. When a flickering disk was steadily viewed in peripheral vision (20°--40° eccentricity), we noticed that after about 10 s it appeared to fade out and disappear (Spillman 1987). psy.ucsd.edu /~sanstis/SARes.html   (1578 words)

Flicker Fusion Frequency as a Measure of Temporal Resolution in the Photoreceptors of Deep-sea Crustaceans.   (Site not responding. Last check: 2007-10-16) Flicker Fusion Frequency as a Measure of Temporal Resolution in the Photoreceptors of Deep-sea Crustaceans. In a photoreceptor functioning in a dim light environment, sensitivity is more important than resolution, which may result in slower photoreceptor transduction and increased summation time, which would be reflected by a lower CFF. Therefore, one would anticipate that organisms living in dim light environments, such as the deep-sea, would have fairly low critical flicker fusion frequencies. www.imbc.gr /biblio_serv/deepsea/X3-0004.html   (209 words)

Richmond Moving Image Co-op - Article, the Flick in FLICKER This flickering image gave rise to the term "flicks" when referring to the movies (and, of course, eventually Flicker). The Egyptians were acquainted with persistence of vision but a satisfactory explanation waited until 1824, when Peter Mark Roget defined it as the ability of the retina to retain an image of an object for 1/20 to 1/5 second after its removal from our field of vision. Look at a window or other bright field and close your eyes.) As the film projects at 24 frames per second (18 frames per second for Super 8!), persistence of vision or "flicker fusion" prevents us from seeing the lines separating the frames, yet helps us retain briefly the image contained within the frame. www.rmicweb.org /flicker/flick.html   (463 words)

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