 Dear students, in this topic we shall discuss about the sensations that is the feelings of various stimuli and the quality of stimulus that is the characters or properties of stimuli. Dear students, sensations are subjective phenomena which are closely associated with the perception of a stimulus. Sensations are produced when a certain stimulus is received at the receptor and receptor transmits signals about that stimulus to the brain. The brain in response interprets and perceives the stimulus. As a result we describe the sensation in words. Neuronal processing or neural perception is a biochemical process that occurs but we describe it in our words that is the subjective phenomena. Feelings or sensations are subjective phenomena. The interpretation of sensations is based on experience and learning that depends on previous exposure of an individual to that stimulus and its description which is stored in the memory. For example, the feelings of pain, color, taste, noise, melody, smell, good or bad smell. These are the sensations or feelings which a person interprets and describes with learning and experience. Dear students, the human sensations depend on the quality of stimulus. The features which are attributed to a particular stimulus which are used to identify and distinguish that stimulus are called the qualities of stimulus. For example, we can say that a sound is received and that sound is noise or that is musical sound. Similarly, quality of light can be described as in the form of colors of light, blue light, red light, green light etc. These are the qualities of stimulus of light. Dear students, as we have just mentioned, sensations are subjective phenomena. Human perception in sensations is subjective. Such descriptive terms are actually not inherent in the stimulus itself. For example, if we call sugar as sweet, then that sweetness is not present in the chemical structure of sugar. Similarly, the color of light, red or blue, is not inherent in the photons. These are the perceptions which have been described subjectively by the human subjects. Dear students, the subjective sensations actually depend on two factors. First, the neuronal processing of the stimulus that produces recognizable sensations. Secondly, it depends on the properties of the sensory receptor cells that send different types of signals to the brain on receiving of different types of stimuli.