Complex sentence: The second aspect is called top-down processing, also known as goal-driven, endogenous attention, attentional control or executive attention: those aspects of our attentional orienting which are under the control of the person who is attending.
Split into simpler sentences: The second aspect is called top-down processing, also known as goal-driven, endogenous attention, attentional control or executive attention. This refers to those aspects of our attentional orienting which are under the control of the person who is attending.