Dermatologic diagnosis relies on vision primarily and auditory and verbal input secondarily. Accurate dermatologic diagnosis is predicated on seeing and perceiving a skin finding, categorizing and naming the finding correctly, and comparing the visual data and data obtained from the totality of the clinical encounter (ie, from other sensory modalities) with one's working mental database of dermatologic diagnoses. The baseline assumption—which is false—is that a dermatologist is an expert at each of the aforementioned steps and transitions sequentially between them seamlessly in an error-free fashion. Each of these steps has inherent challenges, and the transitions between steps can also be problematic. In part 1 of this 2-part report, we describe the pitfalls associated with visual recognition. In part 2, we discuss cognitive heuristics as they relate to the dermatologic diagnostic process and prevention of diagnostic error.