This paper reviews psychophysiological measures applied in Human Computer Interaction (HCI) by mainly focusing on studies related to human cognitive states. Although they have their own disadvantages, psychophysiological measures provide a promising way of user understanding to areas that seek "a sixth sense" for user psychological changes like HCI. We first briefly present the related literature and the major cognitive state assessment measurements. Then, fundamentals of psychophysiological measures are focused in-detail. We provide detailed information concerning their diagnosticity and sensitivity to human cognitive processes in table form. Finally, the paper discusses latest applications and point on the possible future directions.

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This paper presents an easy to implement and fast marker detection method suitable for real-time marker-based human posture tracking. The method works on a color segmentation algorithm based on hysteresis thresholding conducted on meaningful pixels in an image. After the segmentation algorithm is described, the experimental results for an artificial scene are given. Then, the applicability of the method is examined by means of a postural tracking application. The change in elbow angle between upper arm and forearm of a person is tracked during continuous flexion and extension movements with 21.5 Hz frequency for 640x480 resolution. The paper finally introduces the head tracking system developed using the proposed marker detection method.

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