Verbal sounds can be associated with specific meanings, a phenomenon called sound symbolism. Previous findings of sound symbolism have shown that words including specific consonants or vowels or mouth shapes to pronounce specific vowels associate with specific and subjective physical and emotional evaluations. The purpose of this study was to examine whether each written vowel in a given language was individually associated with specific subjective evaluations. Six hundred and thirteen participants used five-point semantic differential scales for 10 features (size, closeness, thickness, width, weight, height, depth, affection, excitement and familiarity) to rate written Japanese vowels (a, i, u, e, and o). The results showed that the size, closeness, thickness and width of a, u and o were significantly higher than those of i and e, whereas the affection and familiarity of a were higher than the others. These results were consistent with previous findings in which vowels in sound-symbolic words have been associated with physical (i.e., size, closeness, thickness and width) and emotional (i.e., affection) evaluations. Our findings suggest that each written Japanese vowel itself, with its individual characteristics, could individually contribute to specific and subjective physical and emotional evaluations. These findings provide insights on how we could better use letters for communicative relationships among writers and readers.

This study reveals associative processes for novel words in a second language (L2) and their referents. Thirty Japanese participants learned associative pairs for novel words in Chinese and pictorial referents (CP), as well as novel words in Chinese and words in Japanese (CJ), against a condition in which they learned only novel words in Chinese (C). After the learning phase, participants conducted two learning condition retrieval tasks for word recognition and three recognition tasks for the source-monitoring of the referents. The correct answers for each recognition task were provided to participants after each trial. Although the correct answers in all conditions increased in both the recognition and learning condition retrieval tasks, there was no significant difference among conditions. In contrast, the response times of the correct trials in all recognition tasks and the first learning condition retrieval tasks were faster for the CP condition than the CJ condition. Additionally, in the second learning condition retrieval task, missed items in associative conditions (CP and CJ conditions) were judged to be learned items more often than unlearned items, whereas missed items in the non-associative condition (C condition) were judged to be unlearned items more than learned items. These findings suggest that pictures contribute to the recognition and retrieval speeds of associations between novel words in L2 and referents, and that associative learning of L2 words and referents could enhance more familiarity effects than the learning of L2 words only.

This study focused on the associative learning of new word forms in the first language and haptic stimuli. In this study, healthy Japanese participants performed three-step tasks. First, participants made nine subjective evaluations of haptic stimuli using five-point semantic differential scales (e.g., regarding stickiness, scored from 1 (not sticky) to 5 (sticky)). Second, the participants carried out learning and recognition tasks for associative pairs of new (meaningless) word forms in their first language (Japanese) and haptic stimulus (H condition), and performed learning and recognition tasks for new (meaningless) word forms only (W condition). The order of conditions was counterbalanced among participants. Third, participants performed free recall tasks. The results of the recognition tasks showed that the proportions and response times of the W condition were better and faster, respectively, than those of the H condition. Furthermore, preference of haptic features negatively correlated with free recall scores of the H condition; however, there was no significant difference between the free recall scores of the H and W conditions. Our results suggest that new word forms were learned better than associative pairs of new word forms and haptic stimuli in a single day of learning. Furthermore, the free recall performance of word forms associated with haptic features could also be affected by their subjective evaluation (preference).

Previous findings have shown essential connections between linguistic and gustatory stimuli for people with autism or lexical gustatory synesthesia. We examined the associative learning of novel linguistic forms in Japanese as a native language and tastes (candies and chocolates) for healthy people. Healthy subjects performed four phases: (a) evaluation phase of gustatory features; (b) learning phases of novel linguistic form and gustatory stimulus pairs (G) or novel word forms (W); (c) recognition memory phases linked with G and W; and (d) free recall phase for G and W. In the recognition memory phases, the performance scores of W were higher than those of G, while there was no significant difference between response times of G and W. Additionally, no difference between recall performances in G and W was also shown. A subjective evaluation of gustatory features (sweetness) negatively correlated with the recall score for linguistic forms connected to the gustatory feature, whereas the accuracy rates of the recognition memory phase in G positively correlated with those of the free recall phase in G. Although learning of novel linguistic forms is more efficient than learning of the relationships between novel linguistic forms and tastes, gustatory features influence the free recall performances of linguistic forms linked with the tastes. These results may contribute to future applications to word learning not just for patients, but also healthy people.

This study aimed to examine whether Japanese participants condition spoken words’ meanings to written pseudowords. In Survey 1, we selected spoken words associated with negative (α = .91) and positive (α = .79) features for Experiment 1 and passive (α = .90) and active (α = .80) features for Experiment 2. In Experiment 1, participants evaluated four written pseudowords’ emotional valence using a 7-point semantic differential scale (1: negative; 7: positive) before and after conditioning spoken words with negative, neutral, or positive features to each pseudoword. In the conditioning phase, participants read each pseudoword, listened to a spoken word, and verbally repeated each spoken word. The results showed that a pseudoword was conditioned to spoken words with positive and negative features. In Experiment 2, participants evaluated four pseudowords’ activeness using a 7-point semantic differential scale (1: passive; 7: active) before and after conditioning spoken words of passive, neutral, and active features to each written pseudoword. In the conditioning phase, the participants read each written pseudoword, listened to a spoken word, and repeated the spoken word. The results showed that the activeness evaluations were more increased for pseudowords conditioned to spoken words of active and neutral features after conditioning than before conditioning but were unchanged for a pseudoword conditioned to those with passive features before and after conditioning. Additonally, Survey 2’s results showed that although the positiveness and activeness responses of the words used in Experiments 1 and 2 were controlled well, the lack of significant differences among positiveness responses of words may influence the evaluative conditioning in Experiment 2. That is, when participants condition passive (low arousal) words’ activeness (arousal) ratings to those of pseudowords, words’ positiveness (valence) ratings would be important in the evaluative conditioning. Our findings suggest that participants can condition spoken word meanings of preference and activeness to those of written pseudowords. It also indicates that linguistically evaluative conditioning’s effects are robust in a non-alphabetic language.