Italian norms for the spontaneous completion of three-letter word stems. A preliminary study

Researchers interested in the study of implicit (and, to a lesser degree, explicit) memory have frequently used word stem completion (WSC) to measure repetition priming in both healthy and clinical populations. In this task, participants are asked to complete each of several stems (e.g., ele__) with the first word that comes to mind (e.g., elephant). A key problem, however, is that the baseline completion rates of the stems corresponding to the target words must be known in advance, if the researcher want to maximize the possibility to detect sizable priming effects. Norms have indeed been developed in a variety of languages (including English, French, Spanish, German, and Swedish), but not in Italian. Here, we report a set of preliminary norms on the spontaneous completion rates of 97 word stems from a group of 115 Italian undergraduate psychology students. They were obtained as part of a pilot study for an experiment investigating the status of implicit memory in the word-stem completion task in schizophrenic patients (Marques et al. Journal of the International Neuropsychological Society, 22(3), 314–321, 2016). In addition, we examined the within-items correlations between the completion rates and five basic properties of the target words (frequency, length, familiarity, imageability, and concreteness). Replicating previous research, we found that spontaneous completion rates were positively associated to word frequency, familiarity, imageability and concreteness, but negatively associated to word length – although in all cases the consistency of the relation across stems was moderate-to-low. The present database can be helpful for Italian researchers to select appropriate words and stems to include in experiments using the WSC