Abstract:

Effects of word frequency (WF) and syllable frequency (SF) have been investigated systematically in the speech production domain, and the facilitation of WF and SF effects have been observed in young Chinese adults. The old people experience more failures than the young people in speech production, such as the tip-of-the-tongue (TOT), which means that speakers know target word's meaning but can’t retrieve its word form successfully. There are different types of hypothesis to explain the failure of word retrieval in speech production: Insufficient Activation Hypothesis assumes that the activation of the target word is too weak to retrieve it. The Interference Theory assumes that the words related to the target words inhibit the process of speech production. The Transmission Deficit Hypothesis assumes that normal aging reduce the activation transmission between meaning and word form of target words which results in more failures. The present study aims to investigate the developmental patterns and the cognitive mechanism of aging in spoken production with young and old native Chinese speakers. 25 young (range: 19-30, male: 8, M = 22.6) and 22 old adults (range: 60-77, male: 15, M = 68.5) sharing the same level of education background participate in the experiment. Sixty target pictures with monosyllabic names were selected. A Chinese character's pronunciation (pinyin) corresponds to one syllable, and thus SF was calculated by accumulating the word frequencies of one syllable (not counting tone). For 60 monosyllabic words, half were high frequency (all ≥130/per million), half were low frequency (≤47/permillion). Among high and low frequency words, half had high SF (≥2558/per million), half had low SF (≤1479/per million). In addition, distractor words that phonologically related or unrelated were chosen for each target picture name in picture-word interference task. During experiment, participants were asked to name pictures as quickly and accurately while ignoring distractor words. The experiment was performed using E-Prime Professional Software on a 21 inch CRT computer screen with a refresh rate of 100HZ. Naming latencies were measured from target onset using a voice-key, connected with the computer via a PST Serial Response Box. Errors were judged and marked by an experimenter during the experiment. We performed repeated measures ANOVAs, one with participants as a random effect (F1) and one with items (F2) as a random effect on responses latencies and error rates. For subject analysis, WF, SF and phonological relatedness were within-participants variables, and Age was between-participants variable. For item analysis, Age and phonological relatedness were within-item variables, and WF and SF were between-items variables. Results indicate that the old took longer time to name a picture than the young. The facilitation effects of WF and SF were observed in both young and old adults, and both WF and SF facilitation effects size were larger in the old than in the young. Critically, we found the interaction pattern of WF and SF in the old but independent pattern in the young. Meanwhile, the young produced a larger phonological facilitation effect than the old, reflecting that the young could benefit more than the old in phonologically related condition, and the old are interference by the phonologically related distractors. Our findings provide evidence for the Insufficient Activation Hypothesis or Transmission Deficit Hypothesis of aging in speech production.