while the three major ones include (1) motivational state, (2) emotional state, and (3) experience. All of these factors, especially the first two, greatly contribute to how the person perceives a situation. Oftentimes, the perceiver may employ what is called a "perceptual defense," where the person will only see what they want to see. The Target: the object of perception; something or someone who is being perceived. The amount of information gathered by the sensory organs of the perceiver affects the interpretation and understanding about the target. The Situation: the environmental factors, timing, and degree of stimulation that affect the process of perception. These factors may render a single stimulus to be left as merely a stimulus, not a percept that is subject for brain interpretation. Multistable perception Stimuli are not necessarily translated into a percept and rarely does a single stimulus translate into a percept. An ambiguous stimulus may sometimes be transduced into one or more percepts, experienced randomly, one at a time, in a process termed multistable perception. The same stimuli, or absence of them, may result in different percepts depending on subject's culture and previous experiences. Ambiguous figures demonstrate that a single stimulus can result in more than one percept. For example, the Rubin vase can be interpreted either as a vase or as two faces. The percept can bind sensations from multiple senses into a whole. A picture of a talking person on a television screen, for example, is bound to the sound of speech from speakers to form a percept of a talking person. Types of perception Vision In many ways, vision is the primary human sense. Light is taken in through each eye and focused in a way which sorts it on the retina according to direction of origin. A dense surface of photosensitive cells, including rods, cones, and intrinsically photosensitive retinal ganglion cells captures information about the intensity, color, and position of incoming light. Some processing of texture and movement occurs within the neurons on the retina before the information is sent to the brain. In total, about 15 differing types of information are then forwarded to the brain proper via the optic nerve. The timing of perception of a visual event, at points along the visual circuit, have been measured. A sudden alteration of light at a spot in the environment first alters photoreceptor cells in the retina, which send a signal