1. A system for human computer interaction (HCI), the system comprising: an image acquirer configured to acquire image data; a line of sight (LOS) catcher configured to detect a first direction indicated by a LOS of a user by detecting a pitch direction and a deflection direction of a head of a user based on the image data; a pose tracker configured to detect a second direction indicated by an appendage of the user; and an interaction determiner configured to determine an interaction based on the first direction and the second direction maintaining a direction facing a display item, wherein the display item is located at a point of intersection between the first direction and the second direction, and wherein the interaction determiner: maintains the interaction in response to determining that either the first direction or the second direction still face the direction of the display item, and concludes the interaction in response to determining that neither the first direction nor the second direction still face the direction of the display item.