Paperclip Polymorphism Issue

console.sh

paperclip steven$ script/console
Loading development environment (Rails 2.3.2)
>> p = Person.new
=> #<Person id: nil, first_name: nil, last_name: nil, design_style: nil, blog: nil, created_at: nil, updated_at: nil>
>> i = p.images.new
=> #<Image id: nil, image_attachment_type: "Person", image_attachment_id: nil, image_file_name: nil, image_content_type: nil, image_file_size: nil, created_at: nil, updated_at: nil>
>> i.image_styles
=> {:small=>"150x150>", :medium=>"300x300>", :large=>"500x500>", :thumb=>"75x75#"}
>> 

create_images.rb

class CreateImages < ActiveRecord::Migration
  def self.up
    create_table :images do |t|
      t.string  :image_attachment_type
      t.integer :image_attachment_id
      t.string  :image_file_name
      t.string  :image_content_type
      t.integer :image_file_size

      t.timestamps
    end
  end

  def self.down
    drop_table :images
  end
end

Image.rb

class Image < ActiveRecord::Base
  # associations
  belongs_to :image_attachment, :polymorphic => true 

  # virtual attributes
  attr_accessor :image_styles

  def after_initialize
    self.image_styles=(set_image_styles)
    # set an obvious fake to test param passing works
    # self.image_styles=(set_image_styles={:thumb=>"10x10#"}) 
  end

  # paperclip
  def set_image_styles(image_styles_hash=nil)
    # allowing for image_styles param let's us pass a custom hash as needed
    case self.image_attachment_type
      when 'User'
      when 'Person'
        image_styles_hash ||= {
              :thumb  => "75x75#",
              :small  => "150x150>",
              :medium => "300x300>",
              :large  => "500x500>"
          }
      else
        image_styles_hash ||= {
            :thumb    => "75x75#",
            :xsmall   => "25x25>",
            :small    => "200x200>",
            :medium   => "500x500>",
            :large    => "800x800>",
            :lightbox => "800x600>"
        }
    end
    return image_styles_hash
  end
  
  # has_attached_file :image, :styles => self.image_styles, :default_style => :small  
end

Person.rb

class Person < ActiveRecord::Base
  # associations
  has_many :images, :as => 'image_attachment', :dependent => :destroy  
end