Phonological Similarity Effect

The phonological similarity effect is the finding that immediate serial recall is worse for a list of letters or words that all sound alike, such as the letters B, C, D, and T, which share similar rhyming sounds, than for a list of items that sound clearly different from one another, even when the confusable items look entirely different in writing and mean entirely different things. Because the impairment depends specifically on how similar the items sound rather than on how similar they look or mean, the effect is taken as strong evidence that immediate verbal memory relies heavily on a code based on sound rather than on visual appearance or meaning, a conclusion that holds even when the material is presented visually rather than spoken aloud. Within Alan Baddeley and Graham Hitch's influential working memory model, the effect is attributed to the operation of the phonological loop, the same proposed short-term storage system implicated in the word length effect documented elsewhere in this section, since a memory store organized around sound-based codes will naturally have more difficulty telling apart, and therefore correctly ordering, several items that all sound similar to one another than items with clearly distinct sounds. Alongside the word length effect, the phonological similarity effect remains one of the two central classic findings supporting the existence of a specialized, sound-based short-term memory component within the broader architecture of human working memory.