Processing Difficulty Effect
Disfluency Effect
The observation that information that takes longer to read and is thought about more is more easily remembered.
Origin
The processing difficulty effect, also called the disfluency effect, was investigated as early as 1988 when researcher Nairne used backward masking with hash marks to make word encoding more difficult, calling it the "perceptual-interference effect." The concept gained prominence following a 2011 study by Diemand-Yauman, Oppenheimer, and Vaughan suggesting that difficult-to-read typefaces could improve learning. The theoretical basis derives from dual-process theory: increased cognitive effort (System 2 processing) leads to deeper engagement with content, thereby improving recall. However, the effect remains controversial, with some research suggesting it may be influenced by individual differences and doesn't universally improve comprehension.