We don’t always see what’s going on around us, especially if it’s moving too fast. For example, if you’re reading this on a computer screen, what you are seeing is being redrawn at a rate of 60-75 times per second (60-75 Hz). Yet we perceive a constant image; why don’t we see the screen flickering?
That’s because the rate of refresh is above our “critical flicker fusion” threshold. For humans, our CFF rate is around 60 Hz. As described by researchers in this paper, CFF “is the lowest frequency of flashing at which a flickering light source is perceived as constant.” The higher the CFF value, the greater the “ability to perceive rapid changes in the visual field.”
The CFF threshold varies for different animals and has implications for animal survival. If you are trying to escape a predator, a smaller and more agile body gives you an advantage. So, too, does a higher CFF, since it give you a greater ability to quickly detect movement. According to data presented in Table 1, dogs have a CFF rate of 75, cats have a rate of 55, and brown rats have a rate of 39. Perhaps the creators of the “Tom and Jerry” cartoons are on to something; the game of cat and mouse may not be as lopsided as we think.
Varying CFF levels may also affect how time is perceived. As described in this article, “small-bodied animals with fast metabolic rates, such as some birds, perceive more information in a unit of time, hence experiencing time more slowly than large bodied animals with slow metabolic rates.” To see what I mean, watch this slow motion video of a Harris hawk.
So time perception may be a function of our eyes, our brain and, at least in the case of humans, our emotional state of mind. In High School, I remember reading a poem by Henry Van Dyke, that helped me understand that time perception can be a function of our state of mind.
Too Slow for those who Wait,
Too Swift for those who Fear,
Too Long for those who Grieve,
Too Short for those who Rejoice;
But for those who Love,
Time is not.
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Source: Santa Clarita News