Cognitive psychologists hypothesize that eyewitness misidentification is a common reason for wrongful convictions in criminal trials. We're only given the contextual information that eyewitness testimony is included in most criminal trials, not the psychologists' specific evidence for their hypothesis.

Cognitive psychologists must have some reason for believing that eyewitness misidentification is a common reason for wrongful convictions. Just because eyewitness testimony features in nearly all trials doesn't mean that it is necessarily an important factor leading to convictions. Besides assuming that eyewitness testimony is a significant factor in the decision to convict, The psychologists also assume that eyewitnesses are mistaken often enough for misidentification to be a common, rather than an occasional, cause of mistaken convictions.