2.54 cm makes something that much bigger - you've got to be joking, right? 2 or 3 inches, maybe... but saying 1 or 1.5 inches is that significant is pushing the envelope a little too much here.
It might help you to think in percentages instead of in absolute terms.
You can also convert height to inches so it makes it easier to compare.
Height: 7 footer vs. 6 footer
7 ft = 84 inches
6 ft = 72 inches
The diff is 12 inches.
12/84 is 1/7 OR .14 which is a 14% difference.
So, there is a 14% difference between 6 feet (72 in) and 7 feet (84 in).
Penis Length: 7 incher vs. 6 incher
The difference is 1 inch.
1/7 = .14 = 14% difference.
So, there is a 14% difference between a 6 inch penis and a 7 inch penis.
Conclusion:
The difference between a person who is 7 feet tall compared to 6 feet tall is equal to the difference between a 7 inch dick and a 6 inch dick, 14% in each case.
Assuming that the differences in scale between 6-7 inches and 6-7 feet do NOT affect one's perception of size, then a 7 inch dick should appear much longer than a 6 inch dick.
However, we should NOT assume that the differences in scale between 6-7 feet and 6-7 inches do not affect one's perception.
Obviously, the differences in scale do affect one's perception -- otherwise, we would not be having this discussion.
Think about it: no matter how much fatter (girthier) a 7 foot tall guy is than a 6 foot tall guy, the 7 foot guy will always appear taller.
But, when perception is based on a smaller scale, such as the difference btwn a 6 inch and 7 inch penis, if the 7 inch penis is much fatter (girthier), then it is possible that the 7 inch penis will appear shorter than a less girthy 6 inch penis.
This
difference in scale is why it is so much more difficult to estimate the length of penises and why girth plays a much larger role in our perceptions of penis length than it does in our perception of height.
Therefore, because girth varies, females cannot estimate the length of penises with a high level of precision just by looking at them.
And neither can many males.
Furthermore, this difference in scale between 6-7 inches and 6-7 feet is also why it might seem to a male that there is not much difference btwn a 7 inch penis and a 6 inch penis (only 1 inch, right?)
But that would be an erroneous viewpoint, because though one may perceive there not to be that great of a difference btwn those 2 penis lenghts, the fact of the matter is that the difference is just as large as the diff btwn a 6 foot guy and a 7 foot guy.
The human's perception apparatus is flawed at smaller scales, but that doesn't change the facts!
I hope this clears up a lot of the confusion for everybody...