Historically, update_attribute and update_attributes are similar, but
with one big difference: update_attribute does not run validations.
These two methods are really easy to confuse given their similar
names. Therefore, update_attribute is being deprecated in favor of
update_column, and will be removed in Rails 4.

See the discussion on rails-core here:
https://groups.google.com/d/topic/rubyonrails-core/BWPUTK7WvYA/discussion