Psychology literature on present bias Does anyone know some good psychology papers on present bias that discusses the psychological mechanisms underlying this bias?

I can only seem to find papers by economist and they tend to give a quite formal and mathematical explanation of the subject. I'm looking for an in depth explanation of the psychology behind present bias.
I think the present bias is a result of the immediate gratification tendency that we as humans have. The following extracts are from the book Smart Change: Break the habits that hold you back and form the habits of success by Art Markman


  One of the most difficult things for people (and other animals for
  that matter) is to pass up something desirable right now in favor of
  something else in the future. A piece of cake now has a stronger pull
  on our actions than having a beach-ready body by next summer. An
  afternoon playing video games feels like a better way to spend an
  afternoon than studying for an exam that won’t happen for another
  week. Checking a few emails at work feels more productive than putting
  in effort on a big long-term project that won’t be finished for
  months. You’re wired to want to do what feels good in the short term.
  
  A beautiful experimental method for looking at the difficulty of
  overcoming temptations was developed by Walter Mischel in the late
  1950s to study how children deal with temptation. In his studies, an
  experimenter asked four-year-old children to sit in a room and showed
  them a small tempting object like a marshmallow or a cookie. Then the
  experimenter placed the object in front of the child next to a bell
  and said that he had to leave the room for a while. If the child was
  able to wait until the experimenter got back, then the child would get
  a larger reward (like two marshmallows or cookies). However, the child
  could ring the bell at any time and just take what was on the plate.
  If the child was able to wait fifteen minutes, then the experimenter
  would come back in the room and give the child the bigger reward.
  
  In a typical experiment, the average child was able to go only about
  ten minutes before ringing the bell. Factored into that average are
  the many children who rang the bell soon after the experimenter left
  the room and others who were able to wait the full fifteen minutes.
  Even for those children who are successful at waiting, it can be a
  difficult experience. In fact, there are a number of popular videos on
  YouTube of children in these experiments agonizing over the
  marshmallows in front of them. It is funny to see the children
  struggle to wait for the bigger reward. But the videos also illustrate
  how hard it can be to overcome temptation.


In the above experiment although the future benefits are clearly better (two instead of one marshmallow), the now is weighted more.