Decode json from php sent by jquery.ajax (POST) Wordpress

I have a json that is stored in the variable projects which is sent by jquery.ajax in this way:

  var proyectos = [{"Paso1": selectEmpStar},{"Paso2": selectEtapa},{"Paso3": selectServ},{"Paso4": selectCarac},{"Paso5": selectCuent},{"Paso6": selecDatos}];

Sending by post the json

  var datos = JSON.stringify(proyectos);
  jQuery.ajax({
    type: 'POST',
    cache: false,
    url:'<?php echo admin_url('admin-ajax.php') ?>',
    data:{ 
    action: 'contact_send',
    dataProyectos : datos,
    dataAsunto : valNombres
    },
    success: function() {
        alert("Mensaje Enviado");
    }
  });

and in wordpress php for sending mail:

function callback_contact_send() {
$send_to = '[email protected]';
$subject = $_POST['dataAsunto'];
$message = $_POST['dataProyectos'];
$headers .= "MIME-Version: 1.0\r\n";
$headers .= "Content-type: text/html\r\n";
$headers .= 'From: proyectos-tecnologicos' . "\r\n" .
'X-Mailer: PHP/' . phpversion();

$mail = mail($send_to,$subject,$message,$headers);
if($mail){
  echo "Mensaje enviado";
}else{
  echo "Error";
}
die();

}

The message arrives correctly but in this way: In what way could the json be formatted and not arrive in that way for a better visualization?