task value aburrimiento académico 1 academic boredom 1 achievement goals 1 afrontamiento del aburrimiento 1 atención 1 attention 1 boredom coping 1 disfrute 1 enjoyment 1 interest 1 measurement 1 motivation 1 regulation of motivation 1 self-regulated learning 1 university students 1 validación 1 validation 1 valor de la tarea 1