Associate a content type to a specific group in drupal commons
I am assuming you are using one group content type, and "Literature" and "Art" are contents of that group type.

Tell me if I am wrong in my assumption.

You can use hook_form_BASE_FORM_ID_alter() to set a default field value for group field based current content type.

    function mymodule_form_node_form_alter(&amp;$form, &amp;$form_state) {
      $node = $form_state['node'];
      if (!isset($node-&gt;nid) || isset($node-&gt;is_new)) {
       global $user;
       $groups = og_get_groups_by_user($user);
          if(is_array($groups)) {
          // This needs to be evaluated to check proper mapping of what field expect to set a default default field value
          if($node['#bundle'] == "poetry" || $node['#bundle'] == "fiction" ||$node['#bundle'] == "novels") {
          $form['group_field_name']['#default'] = $groups[0];  //Whatever index Literature has 
          }
          elseif($node['#bundle'] == "painting" || $node['#bundle'] == "photography" ||$node['#bundle'] == "drawings") {
          $form['group_field_name']['#default'] = $groups[1];  // Art's index
          }
          }
      }
    }