We expected that each of the three analyses would index different aspects of sound symbolism and allow us to
gain a better and deeper understanding of infants’ neural activities relating to meaning integration. We thus focused on how the results from the three analyses could be related and complement one another. Forty-nine healthy Japanese 11-month-old infants participated in this experiment. Informed consent was obtained from all participants (parents of the infants and adults participated in the rating studies) Alectinib of this study after the nature and possible consequences of the studies were explained, and the rights of the participants were protected. All the experimental procedures had
been approved by the Ethical Committee of Tamagawa University, Japan, where the experiment was carried out. We included only those infants who had a minimum of 20 artefact-free trials per condition. Data from 30 infants were excluded from the analyses because of fussiness (N = 23) or insufficient data (N = 7). A total of 19 infants (13 boys, 6 girls, M = 11 months and 25 days, range = 11 months and 6 days to 12 months and 22 days) entered the final analyses. Twenty spiky shapes and twenty rounded shapes, drawn with black lines on a white background, were prepared. Stimulus words and shapes were selected on the basis of the literature on shape sound symbolism (Köhler, 1947, Maurer et al., 2006 and Ramachandran and Hubbard, 2001) and pretests. Each image was presented UK-371804 mouse to infants four times (twice with the matched sound and twice with the mismatched sound) resulting
in 160 randomly ordered trials. In each DCLK1 trial, participants were shown one of the spiky or rounded visual shapes, followed by one of two nonsense words, “kipi” and “moma”, spoken by a Japanese female (400 msec in duration). These words and shapes were selected on the basis of the literature on shape sound symbolism (Köhler, 1947 and Maurer et al., 2006) and pretests. The degree of sound-symbolic match for each combination of shapes and words was highly ranked in pretests including other word-shape pairs in adult speakers of Arabic (N = 18), Japanese (N = 98) and English (N = 83). Examples of the shapes are shown in Fig. 2. Infants were seated on the lap of a caregiver and tested in front of a 37 inch liquid crystal display (SHARP AQUOS LC-37DS5 set to a 1280 × 1024 pixels resolution with a 60 Hz refresh rate) in an electrically shielded and sound attenuated room. The viewing distance was about 1.2 m. Caregivers wore headphones to prevent them from hearing the auditory stimuli and potentially influence their child’s behaviour. Each trial was initiated manually to insure that the infant’s attention was directed towards the screen.