CRITICAL FLICKER FREQUENCY

A New Tool in Wellness Assessment

The fusion frequency, or Critical Frequency of Flicker, abbreviated CFF, is that rate at which the brain recognizes successive light flashes, or flickering, disappears and the light appears to be ‘steady’. CFF is related to persistence of vision[1]. This same persistence phenomenon allows us to see smooth transitions of still frames in a moving picture.

CFF studies on the physiology of vision can be traced back for over a hundred years.  Only recently has CFF been applied to studies on physiological stress and health.  CFF is not the same for every observer.  The fusion frequency is lower for a fatigued or anxious observer. Decrease in the critical fusion frequency has been used as an index for central fatigue[2].   Some medications, alcohol or drugs, as well as a depressed immune system, will also lower your CFF.

Consequently, knowing your subjective CFF can help you assess your personal wellness.  Recent studies indicate that knowing this number may be as important as knowing other common health indicators, such as your blood pressure or cholesterol levels.

While you cannot compare your CFF to someone else’s, once you have established your baseline CFF you can track your overall wellness.  The higher your CFF the healthier you are, the lower your CFF the more stressed and dis-eased you are. 

All NuTesla instruments are able to measure and display your CFF as a two digit number using a series of flashes.  More importantly, after displaying the number each instrument will run a personalized therapy program using your CFF as the base frequency.  Since this is your body’s unique frequency this personalized program reinforces your body’s systems and prepares it for any subsequent program selected by the user.

In addition, NuTesla also offers an instrument dedicated to measuring and displaying your CFF as a two digit number.  By tracking this number you can track your wellness and even the effectiveness of Rhythmedics Bio-Pulses to improve your overall wellbeing.

How CFF is Measured

Critical Flicker Frequency is often measured by having the observer view a rapidly flashing light which appears to be steadily lit.  The frequency of the flashing is then slowed in small steps and the observer presses a button when he or she sees the light begin to flicker.  This point is the Critical Flicker Frequency.  This test is then reversed with the light source flickering at a lower frequency and then increasing in small steps until the light appears steady.

Cone cells are the color sensitive photoreceptor cells in the central region of the retina of the eye and function best in relatively bright light. The motion-sensitive rod cells in the periphery of our retina have little, if any, role in color vision; however they are 100 times more sensitive to light[3].

The CFF Meter

The NuTesla Critical Flicker Frequency Meter uses a red 7 segment display as the source for flicker fusion detection. The 6 outer segments (creating the numeral 0) provide the ambient background illumination, while the central horizontal segment (making the 0 appear as 8) is displayed at a changing rate.

The central horizontal segment will initially appear lit and then will begin to flicker as the observer’s CFF is reached at which point the observer presses a button.  Then the program starts with the central segment flickering at a lower rate and steadily increases it until the segment appears to be continuously lit and user again presses the button.  The average of the two rates will be the CFF for this observer and is displayed as a two digit number.

The red color for the display was chosen because the peripheral portion of the eye which has a high concentration of motion sensitive rod cells is essentially blind to the color red.    This allows the central region cone cells to determine flicker fusion.