Error attempting to input data into PostgreSQL (9.3) array via form (Rails 4.1)

<%= simple_form_for(@risk) do |f| %>
  <%= render 'shared/error_messages', object: f.object %>
  <div class="form-group">
    <%= f.input :title, required: false, :error => false, input_html: { class: 'form-control' } %>
  </div>

  <div class="form-group">
    <%= f.input :description, required: false, :error => false,  as: :text, input_html: { class: 'form-control description' } %>
  </div>

  <div class="form-group">
    <%= f.input :area, :collection => ['Operations', 'IT', 'Finance'], required: false, :error => false, input_html: { class: 'form-control' } %>
  </div>

  <div class="form-group">
    <%= f.input :owner, :collection => User.all, required: false, :error => false, input_html: { class: 'form-control' } %>
  </div>

  <div class="form-group">
    <%= f.input :action, required: false, :error => false, input_html: { class: 'form-control' } %>
  </div>

  <div class="form-inline">
    <span class="date-of-action-input">
    <%= f.input :date_of_action, as: :date, :start_year => Date.today.year - 10, :end_year => 2030,
        :order => [ :day, :month, :year], :required => false, :error => false, input_html: { class: 'form-control' } %>
    </span>
    <span class="action-completed-input">
    <%= f.input :action_completed, as: :boolean, required: false, :error => false, input_html: { class: 'form-control' } %>
    </span>

    <span class="impact-input">
    <%= f.input :impact, required: false, :error => false, input_html: { class: 'form-control' } %>
    </span>
    <span class="likelihood-input">
    <%= f.input :likelihood, required: false, :error => false, input_html: { class: 'form-control' } %>
    </span>
    <span class="submit-risk">
    <%= f.button :submit, :error => false, :error => false, input_html: { class: 'form-control' } %>
    </span>
  </div>
<% end %>

class RisksController < ApplicationController
before_action :signed_in_user
before_action :correct_user, only: [:destroy, :update]


def create
    @risk = current_user.risks.build(risk_params)
    if @risk.save
      flash[:success] = "Risk created!"
      redirect_to root_url
    else
      render 'new'
    end
end

def new
  @risk = Risk.new
end

def destroy
  @risk.destroy
  redirect_to root_url
end

def edit
  @risk = Risk.find(params[:id])
end

def update
  @risk = Risk.find(params[:id])
    @risk.assign_attributes(risk_params)
    if @risk.changed? == false
      flash[:info] = "No changes were made"
      redirect_to root_url
    elsif @risk.update_attributes(risk_params)
      flash[:success] = "The risk has been updated."
      redirect_to root_url
    else
        render 'new'
    end
end

private

    def risk_params
        params.require(:risk).permit(:description, :title, :area, :owner, :action, :date_of_action, :action_completed, { :impact => [] }, { :likelihood => [] })
    end

  def correct_user
    if current_user.admin?
      @risk = Risk.find_by(id: params[:id])
      redirect_to root_url if @risk.nil?
    else
      @risk = current_user.risks.find_by(id: params[:id])
      redirect_to root_url if @risk.nil?
    end
  end

end

# encoding: UTF-8
# This file is auto-generated from the current state of the database. Instead
# of editing this file, please use the migrations feature of Active Record to
# incrementally modify your database, and then regenerate this schema definition.
#
# Note that this schema.rb definition is the authoritative source for your
# database schema. If you need to create the application database on another
# system, you should be using db:schema:load, not running all the migrations
# from scratch. The latter is a flawed and unsustainable approach (the more migrations
# you'll amass, the slower it'll run and the greater likelihood for issues).
#
# It's strongly recommended that you check this file into your version control system.

ActiveRecord::Schema.define(version: 20140617165640) do

  # These are extensions that must be enabled in order to support this database
  enable_extension "plpgsql"

  create_table "risks", force: true do |t|
    t.integer  "user_id"
    t.string   "description"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string   "title"
    t.string   "area"
    t.string   "owner"
    t.string   "action"
    t.date     "date_of_action"
    t.boolean  "action_completed", default: false
    t.string   "impact",           default: [],    array: true
    t.string   "likelihood",       default: [],    array: true
  end

  add_index "risks", ["user_id", "created_at"], name: "index_risks_on_user_id_and_created_at", using: :btree

  create_table "users", force: true do |t|
    t.string   "name"
    t.string   "email"
    t.boolean  "admin",           default: false
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string   "password_digest"
    t.string   "remember_token"
  end

  add_index "users", ["email"], name: "index_users_on_email", unique: true, using: :btree
  add_index "users", ["remember_token"], name: "index_users_on_remember_token", using: :btree

end