Judge Not Thyself, for Thou Art Bad at Judging

I just read an interesting article on the APA's Web site about how people regularly fail to judge themselves and their abilities accurately. This is heavily influenced by culture, as in Western cultures it is more common to believe we really are great at certain things without actually having any evidence to back up these beliefs, whereas in East Asian cultures the tendency is to believe one is not adequately skilled (even if one excels at a skill), with the focus then being placed on self-improvement. I'm sure this is a generalization, but it is still interesting to learn about the ways we routinely deceive ourselves about our skills.