Attention is defined as the process by which organisms select a part of present information upon which it has to focus for acquiring enhanced processing and integration. Attention has mainly three aspects: 1) orienting, 2) filtering, and 3) searching (Barton, 2006). There is a restricted field of view in the human eye, like the vertical dimension has 210 degrees and the horizontal dimension line has 150 degrees (Duh et al., 2001). Therefore, to extract detailed information from a subset of the field of view, the retina shifts themselves so as the image of interested object orient on the central space of the retina, that is called fovea. The fovea bestowed by a high density of photoreceptors, shown in figure 1.1 and 1.2. The process of directing the retina to the image of the target object is called foveation. The physical movement of retina is known as overt visual attention (Itti, 2004). Covert visual attention is a mental shift of attention without physical movement of the eyes (Liechty et al., 2003).