Early temperamental and biological predictors of dimensions of social withdrawal in childhood.

Social wariness and preference for solitude, two dimensions of social withdrawal, show unique associations with various socioemotional difficulties in childhood, including internalizing and peer problems. However, their early childhood predictors remain vastly undocumented. The present study aimed to examine whether early indicators of reactivity in situations of unfamiliarity such as behavioral inhibition, affect, and cortisol independently, or in interaction with emotion regulation as indexed by vagal tone, predict later social wariness and preference for solitude. Participants were 1209 children from the Quebec Newborn Twin Study. Vagal tone was assessed at 5 months, and behavioral inhibition, affect, and cortisol were assessed at 19 months in situations of unfamiliarity. Mothers, teachers, and peers evaluated social wariness and preference for solitude repeatedly from 4 to 10 years old. Findings show that three temperamental dimensions, social inhibition, nonsocial inhibition, and affect accounted for the variability in reactions to unfamiliarity. Behavioral inhibition to social unfamiliarity at 19 months predicted social wariness during the preschool years. Poor vagal regulation at 5 months exacerbated the risk associated with negative affect at 19 months to predict preference for solitude during the preschool years. Overall, results show that social wariness and preference for solitude may follow different developmental pathways.

Medial temporal-lobe damage and memory for emotionally arousing odors.

Recently, we found that healthy young adults remember odors leading to large emotional reactions better than odors provoking smaller emotional reactions. Because the amygdala is believed to be critically implicated in memory for emotionally arousing information and because it is part of the primary olfactory area, we hypothesized that patients with a unilateral medial temporal-lobe resection including the amygdala would not show enhanced memory for arousing compared to nonarousing odors. We tested odor memory in 19 patients (10 left, 9 right) who had undergone a unilateral medial temporal-lobe resection including the amygdala (MTLR) for treatment of intractable epilepsy and 19 healthy control subjects. Healthy individuals and patients with left or right MTLR showed comparable subjective emotional reactions to odors. Similarly, healthy individuals and patients with MTLR remembered unpleasant odors better than pleasant ones. However, unlike healthy individuals, patients with MTLR did not show better memory for emotionally arousing odors compared to nonarousing ones. Patients undergoing a MTLR, whether in the left or right hemisphere, lose the specific memory advantage that odors causing strong emotional reactions normally have.

Olfactomotor activity during imagery mimics that during perception.

Neural representations created in the absence of external sensory stimuli are referred to as imagery, and such representations may be augmented by reenactment of sensorimotor processes. We measured nasal airflow in human subjects while they imagined sights, sounds and smells, and only during olfactory imagery did subjects spontaneously enact the motor component of olfaction--that is, they sniffed. Moreover, as in perception, imagery of pleasant odors involved larger sniffs than imagery of unpleasant odors, suggesting that the act of sniffing has a functional role in creating of olfactory percepts.

Is egocentric space automatically encoded?

Using the criteria defined by Hasher and Zacks [Hasher, L., & Zacks, R. T. (1979). Automatic and effortful processes in memory. Journal of Experimental Psychology: General, 108(3), 356-388], three studies examined the effects of intent of memorization, dual task interference, old age, practice and individual differences on memory for egocentric positions. Results showed that dual task interference and old age slightly influenced memory for egocentric positions. Small but significant individual differences were also observed. However, intent of memorization and practice had no influence on accuracy. The findings demonstrate that encoding of egocentric space works rather automatically but nevertheless requires minimal attentional resources.

A rose by any other name: would it smell as sweet?

We examined whether presenting an odor with a positive, neutral, or negative name would influence how people perceive it. In experiment 1, 40 participants rated 15 odors for their pleasantness, intensity, and arousal. In experiment 2, 30 participants passively smelled 10 odors while their skin conductance (SC), heart rate (HR), and sniffing were recorded. We found significant overall effects of odor names on perceived pleasantness, intensity, and arousal. Pleasantness showed the most robust effect of odor names: the same odors were perceived as more pleasant when presented with positive than with neutral and negative names and when presented with neutral than with negative names. In addition, odorants were rated as more intense when presented with negative than with neutral and positive names and as more arousing when presented with positive than with neutral names. Furthermore, SC and sniff volumes, but not HR, were modified by odor names, and the SC changes could not be accounted for by sniffing changes. Importantly, odor names presented with odorless water did not produce any effect on skin conductance and sniff volumes, ruling out the possibility that the naming-related findings were triggered by an emotional reaction to odor names. Taken together, these experiments show that there is a lot to a name, at least when it comes to olfactory perception.