The role of stem frequency in morphological processing

The aim of the present research is to investigate frequency effects in morphological processing and to provide insights into the role of the stem in lexical access. To this aim we conducted a masked priming experiment associated with a lexical decision task (Forster and Davis 1984) focused on Italian suffixed words, in which we manipulated the frequency of the stem of the target words with respect to the derivative primes. More precisely, we opposed high frequency stem targets (e.g., trasferimento ‘transfer’- trasferire ‘to transfer’) to low frequency stem targets (e.g., motivazione ‘motivation’ - motivare ‘to motivate’); the frequency of the primes, on the other hand, was comparable. Results show full morphological priming effects for both types of targets, irrespective of stem frequency. This suggests that suffixed words are accessed holistically and not through the stem and therefore via a decomposition process, as suggested by previous studies based on simple lexical decision tasks. We argue that, while the lexical decision task is not suited to explore the very early stages of word recognition, given that the derived word is perceived consciously, masked priming focuses on fast automatic non-conscious mechanisms of lexical access, as the activation of the masked prime is constrained by strictly determined time limits. The masked priming paradigm therefore does not examine the entire process of word recognition as the lexical decision task does, but represents a window on the transfer of activation between a prime and a target.