The effects of near, medium, and far prior speech context on function word perception

When listening to rapid, casual speech, humans effortlessly perceive boundaries between words that may be only weakly encoded in the acoustic information. Research into the temporal characteristics of speech has demonstrated that when context speech rate is manipulated, the number of words heard by a listener can be altered. Building on this research, this study investigated how specific manipulations of different portions of recorded speech can produce a disappearing word effect in which a heavily co-articulated function word may be perceived as a part of the preceding syllable, e.g., “John didn’t tell the junior or representative about it.” The stimulus conditions entailed different numbers of syllables expanded/slowed, starting from the beginning of the sentence up through the target portion. Participants (n=34) listened to these sentences and typed what they heard. Results were analyzed for proportion of function words reported. It was found that all slowed conditions resulted in a decreased frequency of hearing function words. A stronger effect was associated with additional expanded syllables. These results suggest that slowing non-adjacent prior context elicits the LRE, a finding that may inform communicative disorders research including dyslexia intervention.