A synesthetic walk on the mental number line: the size effect

Are small and large numbers represented similarly or differently on the mental number line? The size effect was used to argue that numbers are represented differently. However, recently it has been argued that the size effect is due to the comparison task and is not derived from the mental number line per se. Namely, it is due to the way that the mental number line is mapped onto the task-relevant output component. Here synesthesia was used to disentangle these two alternatives. In two naming experiments a digit-color synesthete showed that the congruity effect was modulated by number size. These results support the existence of a mental number line with a vaguer numerical representation as numbers increase in size. In addition, the results show that in digit-color synesthesia, colors can evoke numerical representation automatically.     

The Still-Face Paradigm and bidirectionality: Associations with maternal sensitivity,self-esteem and infant emotional reactivity

The Still-Face Paradigm (SFP) is a structured stressful event within which researchers have investigated the influence of maternal psychological and behavioral characteristics on infant behavior. The present investigation contributes to this body of work by examining the joint contributions of maternal and child behavioral and affective characteristics on subsequent behaviors and affectations following the SFP. A sample of non-clinically depressed mothers and their infants (n = 31) engaged in a modified Still-Face Paradigm (SFP), followed by a period of toy play. These interactions were videotaped and behaviorally coded along the following dimensions: maternal sensitivity prior to the SFP and during toy play, infant negative emotional reactivity during the still-face, and infant resistance during the reunion phase. Additionally, mothers reported global self-esteem and this was examined as a predictor of infant behavior. Results revealed significant bidirectional influences such that maternal self-esteem predicted infant emotional reactivity, maternal sensitivity pre-SFP predicted infant resistance during the reunion phase, and infant resistance predicted subsequent levels of maternal sensitivity. Indirect effects were also examined, and provided additional support for bidirectionality in mother–infant interactions. Implications for clinical practice are discussed in light of these findings.