jquery demo

demo.js

<select id="sel1">
  <option>Eric</option>
  <option>Joe</option>
</select>

<p id="eric" class="hidden">Hi, I'm eric</p>
<p id="joe" class="hidden">Hi, I'm joe</p>

$(document).ready(function(){

  $("#sel1").change(function() {
    var value = $(this).val();
    if (value == "eric") {
      $("#eric").removeClass('hidden');
      $("#joe").addClass('hidden');
    } else if {
      // same but switched
    }

  });

})