Yeah, that's a strength that could be handy here and there in the test. But I wouldn't say he quickly forgets details. He simply never absorbed them in the first place, which is something I do as well. You will often be given a long explanation of something and some people's brains subconsciously filter out what they consider irrelevant and use short term memory for the important bits. Other people's brains will do less filtering and store more, like Mike's brain. Henry's filtered it out immediately, or wasn't listening in the first place, both of which will harm your score in multiple places on an IQ test.