Emotional enhancement effect of memory: removing the influence of cognitive factors

According to the modulation hypothesis, arousal is the crucial factor in the emotional enhancement of memory (EEM). However, the multifactor theory of the EEM recently proposed that cognitive characteristics of emotional stimuli, e.g., relatedness and distinctiveness, also play an important role. The current study aimed to investigate the individual contribution of arousal to the neural correlates of the EEM by controlling for these additional cognitive factors. We observed the characteristic neuronal correlates of the EEM, in particular enhanced activity in the amygdala and hippocampus, which provides evidence for an arousal-driven EEM in the amygdala as proposed by the modulation hypothesis.     

Chronic stress modulates the use of spatial and stimulus-response learning strategies in mice and man

Acute stress modulates multiple memory systems in favor of caudate nucleus-dependent stimulus-response and at the expense of hippocampus-dependent spatial learning and memory. We examined in mice and humans whether chronic stress has similar consequences. Male C57BL/6J mice that had been repeatedly exposed to rats ("rat stress") used in a circular hole board task significantly more often a stimulus-response strategy (33%) than control mice (0%). While velocity was increased, differences in latency to exit hole, distance moved or number of holes visited were not observed. Increased velocity and performance during retention trials one day later indicates altered emotionality and motivation to explore in rat stressed mice. Forty healthy young men and women were split into "high chronic stress" and "low chronic stress" groups based on their answers in a chronic stress questionnaire ("Trier Inventory of Chronic Stress"-TICS) and trained in a 2D task. A test trial immediately after training revealed that participants of the "high chronic stress" group used the S-R strategy significantly more often (94%) than participants of the "low chronic stress" group (52%). Verbal self-reports confirmed the strategy derived from participants' choice in the test trial. Learning performance was unaffected by the chronic stress level. We conclude that one consequence of chronic stress is the shift to more rigid stimulus-response learning, that is accompanied by changes in motivational factors in mice.     

Who is causing what? The sense of agency is relational and efferent-triggered

The sense of agency ("I did that") is a basic feature of our subjective experience. Experimental studies usually focus on either its attributional aspects (the "I" of "I did that") or on its motoric aspects (the "did" aspect of "I did that"). Here, we combine both aspects and focus on the subjective experience of the time between action and effect. Previous studies [Haggard, P., Aschersleben, G., Gehrke, J., & Prinz, W. (2002a). Action, binding and awareness. In W. Prinz, & B. Hommel (Eds.), Common mechanisms in perception and action: Attention and performance (Vol. XIX, pp. 266-285). Oxford: Oxford University Press] have shown a temporal attraction in the perceived times of actions and effects, but did directly not study the relation between them. In three experiments, time estimates of an interval between an action and its subsequent sensory effect were obtained. The actions were either voluntary key press actions performed by the participant or kinematically identical movements applied passively to the finger. The effects were either auditory or visual events or a passive movement induced to another finger. The results first indicated a shortening of the interval between one's own voluntary action and a subsequent effect, relative to passive movement conditions. Second, intervals initiated by observed movements, either of another person or of an inanimate object, were always perceived like those involving passive movements of one's own body, and never like those involving active movements. Third, this binding effect was comparable for auditory, somatic and visual effects of action. Our results provide the first direct evidence that agency involves a generalisable relation between actions and their consequences, and is triggered by efferent motor commands.     

Dynamic binding of identity and location information: a serial model of multiple identity tracking

Tracking of multiple moving objects is commonly assumed to be carried out by a fixed-capacity parallel mechanism. The present study proposes a serial model (MOMIT) to explain performance accuracy in the maintenance of multiple moving objects with distinct identities. A serial refresh mechanism is postulated, which makes recourse to continuous attention switching, a capacity-limited episodic buffer for identity-location bindings, indexed location information stored in the visuospatial short-term memory, and an active role of long-term memory. As identity-location bindings are refreshed serially, a location error is inherent for all other targets except the focally attended one. The magnitude of this location error is a key factor in predicting tracking accuracy. MOMIT’s predictions were supported by the data of five experiments: performance accuracy decreased as a function of target set-size, speed, and familiarity. A mathematical version of MOMIT fitted nicely to the observed data with plausible parameter estimates for the binding capacity and refresh time.     

Extending the Rorschach trauma content index and aggression indexes to dream narratives of children exposed to enduring violence: an exploratory study

In this study, we compared dream narratives of children and adolescents living under conditions of enduring interpersonal violence (n = 220) versus those living in peaceful surroundings (n = 99) on content variables that have been associated with traumatic experiences in Rorschach (Exner, 1995) imagery. As predicted, children and adolescents living in circumstances of enduring violence reported a higher proportion of content scorable by Armstrong and Loewenstein's (1990) Trauma Content Index and a much higher proportion of aggressive objects in their dreams (AgC; Gacono & Meloy, 1994). In support of discriminant validity, no consistent group differences were observed for the relative frequencies of Animal (A), Clothing (Cg), or Cooperative movement (COP) content. The modest association between manifest dream content and psychological symptom scales suggests that the former may alternatively reflect adaptive or psychopathological processes. Our findings suggest that content analysis of dreams may be a valuable adjunct in tapping the psychological state of children traumatized by violence.     

Temperament and migration patterns in Finland

Migration is a central determinant of population dynamics and structure. We examined whether three major temperament traits--sociability, emotionality, and activity--predicted migration propensity, selective urban-rural migration, and migration distance in a 9-year prospective study in Finland. The participants were Finnish women and men (N= 1,733) ages 15 to 30 years at baseline. The home municipality's position on the urban-rural continuum was assessed on the basis of the municipality's population density. We found that high sociability predicted migration to urban areas and longer migration distances. High activity increased general migration propensity (including migration to both urban and rural areas). High emotionality increased the likelihood of leaving the home municipality and decreased migration distances, but was not associated with selective urban-rural migration. These data suggest that temperament predicts the self-selection of environments on a demographic scale and may be relevant in understanding population dynamics.