Our strongest perception of sick regarding other people, obviously is based on our visual acuity. Once again, our eyes trying to make sense of what we see. Expectations are fulfilled when we view pale skin, the lesions of Karposi s sarcoma, emaciation, dull eyes, and so on. In addition to our past knowledge, this human visual concept of sick also prepares or predicts in our minds future images of how an individual will appear as a particular disease runs it course. Thus, it enables our cognitive processes to project visual expectations of how someone will look in the future under the sentence of a known, progressive, terminal disease.
People actually use rules to identify concepts.
The coupling of the words, sick and person are similar to the idea of describing a square as being red. Both concepts have two attributes at the same time. To belong to these concepts, an item must be both a person and sick, or a square and red, respectively. In the real world, concepts such as the red square may be clearer in our minds than the sick person. Add to this reality the fact that some items are more typical, or better examples of a concept, than others.