Reddit mentions of Psychology

I have a copy of the cards; they're not super helpful and are pretty massively overpriced imo. The book doesn't handle player psychology in a very rigorous way (and there's only one chapter on it) but I'm probably a lot more picky about that than most people.

I haven't read it yet but Glued to Games looks pretty good coming from authors with a bit more experience in psychology. Their work is on the motivational aspect of game playing: why people play games and how some games satisfy their intrinsic needs better than others. The basic argument is that "fun" or "engagement" are outcomes of need satisfaction.

Other than that though I think there's not much work applying psychology to game design directly. A Theory of Fun is based on pop-psych and (in my opinion) a questionable understanding of cognitive science, but it's a fun read at least.

In terms of blogs this one is good:www.psychologyofgames.com although it's mostly focused on phenomena around games (sales, reception, player attitudes) rather than the act of playing itself. This blog reviews recent academic literature in psychology (and a few other fields) related to games.

If you're really interested you'd probably be best served picking up an introductory psych textbook (I like Gleitman's) and picking out the sections that are most relevant to what you're interested in. I could give you more specific topics or books to look into if you have a particular part of player psychology you're interested in.