The Von Restorff effect (named after psychiatrist and children’s paediatrician Hedwig von Restorff 1906–1962), also called the isolation effect, predicts that an item that “stands out like a sore thumb” (called distinctive encoding) is more likely to be remembered than other items. A bias in favour of remembering the unusual.
Modern theory of the isolation effect emphasizes perceptual salience and accompanying differential attention to the isolated item as necessary for enhanced memory. In fact, von Restorff, whose paper is not available in English, presented evidence that perceptual salience is not necessary for the isolation effect. She further argued that the difference between the isolated and surrounding items is not sufficient to produce isolation effects but must be considered in the context of similarity.
Von Restorff worked as a postdoctoral assistant to Wolfgang Köhler at the Psychological Institute of the University of Berlin up to the time that Köhler resigned in protest against Nazi interference with the Institute. (Köhler’s resignation in 1935 was precipitated by the dismissal of his postdoctoral assistants, who included not only von Restorff but also Karl Duncker)
During her time in Köhler’s laboratory, von Restorff published two papers, the second of which she co-authored with Köhler (Köhler & von Restorff, 1935). Von Restorff proposed the isolation effect in a paper she wrote in 1933 on the topic of spontaneous reminding which included a prescient discussion of the role of intentionality in the memory test.
For instance, if a person examines a shopping list with one item highlighted in bright green, he or she will be more likely to remember the highlighted item than any of the others.