The "extra possession means extra utility" assumption, and the upsell.

glennmagusharvey

What's an "upsell"?  It's when you buy more than you expected to buy.  It's when you get chips and a soda to go with that burrito.  It's when you buy a vendor-based protection plan for that new laptop, for just $29.99 a year or something.  It's when you go get Neverwinter Nights 1 because GOG suggested it to you after you bought Neverwinter Nights 2.

What assumption underlies this behavior?

It is the assumption that I've awkwardly worded as the "extra possession means extra utility" assumption.  Basically, this just means the idea that having more stuff makes one more satisfied.  Which is not exactly true.  Though the complete opposite -- that having less, or not having any more, will lead to satisfaction -- isn't true either.

What having more stuff actually does is it increases the "option space" for what one can do.  Especially in the case of "essential" items, it would seem like having a backup option is desirable.  However, that's only thinking on one side of the matter.  That's because, in addition to the benefits that having more stuff brings, possessing stuff also has costs.  For example, it's easier to clean a non-cluttered room than to clean a cluttered one.  Having too much might mean one has a higher chance of losing things -- in which case the entire value of those things is forfeited anyway.

So, therefore, one's mental model of deciding whether to buy something else should be revised from this:

if cost < benefit , then buy

to this:

if cost + detriments < benefits , then buy

Naas_Human

What having more stuff actually does is it increases the "option space" for what one can do.  Especially in the case of "essential" items, it would seem like having a backup option is desirable.

1) what do you mean by "essential"?

2) The "option space" thing makes me think of Lego or similar construction toys. Having more bricks (and/or other component pieces) means means there's even more you can do. And your options don't just go up linearly since they're much more versatile. I'm not sure why I felt the need to add this.

glennmagusharvey

1. Things perceived as necessities.  Such as food, or transportation.

2. Well, that's because you're assuming no limitations on the amount of storage space, processing space, and construction time for your legos.

Stormtroper

But rummaging through the pieces is half the fun!