Tessei Kobayashi

Relative quantity judgment by Asian elephants (Elephas maximus)

This study investigated whether Asian elephants can make relative quantity judgment (RQJ), a dichotomous judgment of unequal quantities ordered in magnitude. In Experiment 1, elephants were simultaneously shown two baskets with differing quantities of bait (up to 6 items). In Experiment 2, elephants were sequentially presented with baits, which could not be seen by elephants in their total quantities. The task of elephants was to choose the larger quantity in both experiments. Results showed that the elephants chose the larger quantity with significantly greater frequency. Interestingly, the elephants did not exhibit disparity or magnitude effects, in which performance declines with a smaller difference between quantities in a two-choice task, or the total quantity increases, respectively. These findings appear to be inconsistent with the previous reports of RQJ in other animals, suggesting that elephants may be using a different mechanism to compare and represent quantities than previously suggested for other species.

Baby arithmetic: one object plus one tone

Recent studies using a violation-of-expectation task suggest that preverbal infants are capable of recognizing basic arithmetical operations involving visual objects. There is still debate, however, over whether their performance is based on any expectation of the arithmetical operations, or on a general perceptual tendency to prefer visually familiar and complex displays. Here we provide new evidence that 5-month-old infants recognize basic arithmetic operations across sensory modalities. Using a violation-of-expectation task that eliminated the possibility of the familiarity and complexity preference, 5-month-old infants were presented alternatively with two types of arithmetical events: the expected, correct outcomes of operations (1 object+1 tone=2 objects and 1 object+2 tones=3 objects) and the unexpected, incorrect ones (1 object+2 tones=2 objects and 1 object+1 tone=3 objects). Results showed that subjects looked significantly longer at the unexpected events than at the expected events, suggesting that infants are able to recognize basic arithmetic operations across sensory modalities.

Audiovisual matching of lips and non-canonical sounds in 8-month-old infants

Japanese 8-month-olds were tested to investigate the matching of particular lip movements to corresponding non-canonical sounds, namely a bilabial trill (BT) and a whistle (WL). The results showed that the infants succeeded in lip-voice matching for the bilabial trill, whereas they failed to do so for the whistle.

Perception of a Japanese moraic obstruent in a discrimination task

Previous research with an identification task suggests that native Japanese speakers perceive a moraic obstruent categorically (Amano et al., 2005). However, it is still unclear whether the suggestion would be confirmed by other tasks. This study used an AX discrimination task to investigate whether the performance is highly sensitive around the perceptual boundaries that were obtained from the identification task. Native Japanese speakers (N=40) were presented with a pair of two‐mora nonsense syllables (/bipa/, /guku/, /kuku/, /kuto/) and then required to judge whether the stimulus pair was acoustically identical. The stimulus set was produced by reducing or increasing the closure duration between the successive moras in 5‐ms steps (−95 to 240 ms). Results showed that the participants discriminated more precisely around closures duration ranging from approximately 150 to 180 ms (/bipa/: 180 ms, /guku/: 160 ms, /kuku/: 155 ms, /kuto/: 175 ms). Although the results indicate, to some degree, the possibility...

Perception of a Japanese moraic obstruent in an identification task

Native Japanese speakers perceive a moraic obstruent when the closure duration between successive moras is longer than a normal obstruent. However, it has not been well clarified how the perception of the moraic obstruent relates to the closure and neighboring moras’ duration. To investigate this point, a perceptual experiment was conducted with stimuli consisting of two‐mora nonsense syllables with a closure between the moras (/bipa/, /guku/, /kuku/, /kuto/, and /tapi/). The closure duration was shortened or lengthened in 10‐ms steps. The duration of the first mora was modified by changing its vowel duration to 50%, 100%, and 150% by the STRAIGHT method. Forty native Japanese speakers identified whether the nonsense syllable contained a moraic obstruent with the 2AFC method. Results showed that the perceptual boundaries of the moraic obstruent were 182 ms (SD=13.2 ms), 204 ms (SD=14.7 ms), and 222 ms (SD=16.6 ms), respectively, with 50%, 100%, and 150% vowel durations in the first mora, and that a logist...