 A mental representation or cognitive representation in philosophy of mind, cognitive psychology, neuroscience, and cognitive science, is a hypothetical internal cognitive symbol that represents external reality, or else a mental process that makes use of such a symbol, a formal system for making explicit certain entities or types of information. Together with its specification of how the system dish this mental representation is the mental imagery of things that are not actually present to the senses. In contemporary philosophy, specifically in fields of metaphysics such as philosophy of mind and ontology, a mental representation is one of the prevailing ways of explaining and describing the nature of ideas and concepts. Mental representations or mental imagery enable representing things that have never been experienced as well as things that did not exist. Think of yourself traveling to a place you have never visited before, or having a third arm. These things have either never happened or are impossible and do not exist, yet our brain and mental imagery allows us to imagine them. Although visual imagery is more likely to be recalled, mental imagery may involve representations in any of the sensory modalities, such as hearing, smell, or taste. Stephen Costlin proposes that images are used to help solve certain types of problems. We are able to visualize the objects in question and mentally represent the images to solve it. Mental representations also allow people to experience things right in front of them though the process of how the brain interprets the representational content is debated.