[thedoc (OP)]

When you first look at a clock with a second hand, why does that first second always take so long to tick?
Asked by Dan Wheeler

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[JeepKeen]

It doesn't, just tested.

[Bored chemist]

It doesn't, just tested.

Ditto

[RD]

I have perceived this delay with analogue clock second-hand & with digital clock displays which blink every second ...

The best-known version of this illusion is known as the stopped-clock illusion, wherein a subject's first impression of the second-hand movement of an analog clock, subsequent to one's directed attention (i.e. saccade) to the clock, is the perception of a slower-than-normal second-hand movement rate: when first observing the second hand it appears to remain stationary for longer than the subsequent periods between movements

https://en.wikipedia.org/wiki/Chronostasis

[Craig W. Thomson]

When you first look at a clock with a second hand, why does that first second always take so long to tick?

Probably some sort of optical illusion. An example that's sort of the same is the rising moon. It looks larger when near the horizon than when it's overhead. This is because our brain expects things to be a certain way. If a hot air balloon was over your head, it would tend to look larger, then get smaller as it approached the horizon. The brain tends to interpret the moon as something that would behave the same way. Your brain thinks the moon should get smaller as it heads toward the horizon, so when it stays the same size, your brain compensates by telling you it's larger than it actually is. I suspect your clock is the same. When you look at it, you expect the second hand to be moving, so when it isn't, your brain exaggerates the effect.

[RD]

Probably some sort of optical illusion. An example that's sort of the same is the rising moon. It looks larger when near the horizon than when it's overhead.

A better analogy is when a YouTube video slows or freezes because of a momentary sub-normal data delivery rate.