(PaperTrail Extension) If you just want a summary of changes for a particular attribute of a model, you can use the history_from_audits_for method

paper_trail.rb

# config/initializers/paper_trail.rb
PaperTrail::Model.module_eval do
  # return an array of changes for specific attribute (old to newer)
  # Sample use: Subscriber.find(2).history_from_audits_for(:first_name)
  # Sample result: [{version: <PaperTrail::Version>, model: <Subscriber>}, {version: <PaperTrail::Version>, model: <MyModel>},....]
  # Sample print: Subscriber.find(2).history_from_audits_for(:first_name).map{|item| item[:model].first_name }
  # Required: Diffing Versions of paper trail
  def history_from_audits_for(attr_name)
    res = []
    self.versions.each do |v|
      vv = v.reify
      next if vv.nil?
      res << {version: v, model: vv} if v.changeset.include?(attr_name.to_s)
    end
    res
  end
end