<!DOCTYPE html><!--[if lt IE 8]><html class="no-js lt-ie8 lt-ie9" lang="en"><![endif]--><!--[if IE 8]><html class="no-js lt-ie9 ie8" lang="en"><![endif]--><!--[if IE 9 ]><html class="no-js ie9" lang="en"><![endif]--><!--[if !(IE)]><!--><html class="no-js" lang="en"><!--<![endif]--><html><head><title>Guides - Mental modelling</title><meta charSet="utf-8"/><meta name="google-site-verification" content="fXPmqCfxWVHNxpSlw6Bm6pmuUcMuTILat3eixX8gbM8"/><meta http-equiv="x-ua-compatible" content="ie=edge"/><meta na