It occurs to me, that 99% of the time I prefer the 1st half of a CD to the 2nd half. I've never been certain why.
Do you really mean "99%"? I'm guessing that's an exaggeration, so do you have a non-exaggerated estimate? I just looked at the first 20 albums in my iTunes database and made a snap judgement on whether I prefer the first half, second half, or can't tell.
First:2
Second:3
Neither: 15
My gut feel before doing this marginally-more-scientific check was that I don't have a strong preference, but when averaging over a very large sample space, first half might slightly win out over second half due to your hypothesis #1 (artists loading the front half with stuff they think is better). So my 20-album check generally supported that idea.
Additionally, I feel that if I averaged my whole collection, the front halves of albums (particularly the first 4 tracks or so) would get a slightly higher-than-average rating, then there would be a dip in the middle/second-half, only to shoot up again on the final track or two, which for me, are often the best songs on the whole record (they're often where an epic/expansive/moody/experimental song goes, and that's the stuff I most like).
1. The first half is the stronger half. Bands put their strongest songs towards the front, in order to grab the listener's attention.
I think in the long term average, this probably holds some weight, but the overall effect is fairly minor relative to the other possibilities. This is still music we're talking about, where there is no objective truth, so the idea of "strongest songs" is still just an opinion. Even if it's the band's opinion. They could have shit for taste. (e.g. Jon Schaffer disliking 'Burnt Offerings'. What a dumbass!) Furthermore, what makes a song "good" in terms of selling records (punchy, short, simple, repetitive) may be the exact opposite of what makes a "good" song over long-term listening. But, within a particular style, there is at least *some* consensus on what is "good" and what is "boring", so that's why this effect isn't totally cancelled out by randomness.
2. Familiarity. I find I listen to the 1st half of a CD more frequently. Whether it's because I'm in the car, at the gym, at work or listening before bed, I rarely have time to make it through an entire CD.
First, just a mechanical question. Is there something that keeps you from re-starting an album from where you left off? I thought you were mostly using an electronic music player? When I'm leaving home or work, I just pause/stop my PC-based player, and then pick it back up when I return. Same with the car, my phone plays until I unplug it, and then after a day at work listening to other stuff, I continue on with that morning's album for the drive home. And I thought even modern CD players remember your spot on power-down?
Since I don't have a strong front/back preference, AND I always listen to albums in their entirety, I don't have much standing to judge the effects of partial listening. But by reading the responses in the thread and trying to correlate front-preference with partial-listening-preference, it seems that there may be a correlation there. Particularly when reading people say how changing listening modes (shuffle, etc.) can change their opinions on songs.
When music fans are whining about record companies and trying to justify their own behavior, you'll often hear the line "They trick you into buying the album, but you find it only has two good songs, and then a load of filler!" I've always thought this was mostly nonsense, given that one man's trash is another man's treasure, so the concept of "filler" isn't really a viable one. I think the real truth is that people greatly underestimate the effect of repetition on their affinity for a song, and thus, the "singles" they listened to on the radio/YouTube a bunch of times initially seem much better than everything else on the album, and if they then continue to focus solely on those songs, the rest of the songs have no chance to catch up. Some of the posts here seem to support that idea, and then preferring the first half of an album is just an extension of that effect.
(edit: conveniently, this meshes nicely with what I wrote about in your Iron Maiden thread a little while back. When Iron Maiden plays their new stuff in concert, they're effectively forcing you to "listen to the entire album", and thus gain an appreciation for songs that they know you'll grow to like, but wouldn't explore without their prodding.)
3. The style grows tiresome. The music most bands write lacks diversity. Consequently, the songs begin to run together as the disc goes on.
This certainly must have some effect, but probably not a great one. And if you were doing a specific survey as I described above, this effect should actually disappear, since, when asking "do I like track #8 more or less than track #1?", getting tired of the sound won't factor in, since you actually aren't listening to the album.
4. Attention Deficit Disorder. Like most Americans, I have the attention span of house fly and all but 10/10 discs have any chance of holding my attention.
I think this is just a restatement and combination of issues #2 and #3.
So I'll give 60% of the effect to #2, and 20% to #1 and #3.
One scary corollary to this is that it makes it very difficult to talk helpfully to each other about music. When we talk about how good an album is, we may be effectively talking about two entirely different things...you could be talking about tracks #1-#4, while I'm talking about tracks #1-12. Depending on where the "good" songs are located, our opinions on "the album" could be very different, even when our tastes are exactly the same.
Neil