 The relation between the sample stimulus and the correct comparison stimulus can be varied in order to alter the difficulty of the task. For example, the sample stimulus and the correct comparison stimulus may be identical, often referred to as identity matching. This is the easiest form of DMTS. Alternatively, the sample stimulus may be related to the correct comparison stimulus in an abstract dimension. For example, the sample stimulus may be the written word car and the correct comparison stimulus might be a bicycle, with a gorilla and a fork as distracters. 