Similarity and Intrusions in Short-term Memory for Consonant-vowel Digrams

Abstract

Subjects listened to lists of six consonant-vowel digrams presented at the rate of 0·8 sec./digram and copied them as they were being presented. Immediately after finishing copying the list, they attempted ordered recall of the six digrams. The digrams in each list were chosen from a population of eight digrams consisting of all digrams that can be constructed from the consonants “f” and “n,” the vowels “ā” and “Ō,” and the two orders “CV” and “VC.” Intrusions tended to be similar to the presented digram, and the frequency of an intrusion was a monotonic increasing function of degree of similarity to the presented digram. The ordering of intrusion frequency for each similarity type was from greatest to least: +−+ (same consonant, different vowel, same order), + + −, − + +, − + −, + − −, − − +, − − −. The findings indicate that forgetting is not all-or-none, that digrams are coded in terms of phonemes, and that initial vs. terminal position is a distinctive feature of consonants, but not vowels, in short-term memory.