app-models-survey-boolean_survey.rb

class BooleanSurvey < Survey
  def self.translate_answer(answer)
    ActiveRecord::ConnectionAdapters::Column.value_to_boolean(answer)
  end
end

app-models-survey.rb

class Survey < ActiveRecord::Base
  attr_accessible :end_date, :start_date, :title, :question
  validates :title, :presence => true

  # Returns a string interpretation of the answer given.
  # @note This should be overriden by specific survey types.
  def self.translate_answer(answer)
    answer.to_s
  end
end

result

subject.class
=> Survey::BooleanSurvey(id: integer, title: string, start_date: date, end_date: date, created_at: datetime, updated_at: datetime, question: string, type: string)

subject.class.translate_answer('test')
=> "test"

Survey::BooleanSurvey.translate_answer('test')
=> false