Influence of Maternal Social Communication on Ticklishness in Infants: A Comparison With Being Stroked

The tickle sensation is considered to arise from physiological and social factors. Previous research reports that although infants laugh in response to tactile stimulation in first 6 months of life, they cease laughing to this stimulation as they grow. Because older children often appear to laugh in response to tickling, the current study focused on relationships between infants’ response to tickling and social factors as they grow. Specifically, we examined effects of different maternal social interactions on infants’ reactions to tickling vs. stroking tactile stimulations. Results showed that a tickle stimulus, together with maternal communications, elicits positive reactions in infants. In contrast, a noncommunicative mother and stroking tends to elicit from the child a neutral response, whereas the combination of a noncommunicative mother with tickling evokes negative reactions in infants. These findings suggest that maternal social communication affects infants’ reactions to touch. In addition, the combination of tactile and social stimulations elicits laughter in infants over 6 months of age.     

Effects of female body size and timing of nest foundation on the reproduction of the Japanese paper wasp,Polistes jadwigae Dalla Torre (Hymenoptera: Vespidae)

Summary Females in hibernation site (FH) were significantly larger than foundresses (FO), suggesting that larger FH were less successful in founding their nest. Body size of FO did not correlate with two nest characters, i.e., the number of cells at pupal stage (CP) and the timing of nest foundation (DP). However, CP negatively correlated with DP in 2 of 3 studied years, suggesting that foundress who founded her nest earlier than others tended to construct larger number of cells irrespective of her body size.