Inactivation of the ventral tegmental area abolished the general excitatory influence of Pavlovian cues on instrumental performance

Pavlovian stimuli can markedly elevate instrumental responding, an effect known as Pavlovian-instrumental transfer (PIT). As the role of the ventral tegmental area (VTA) in PIT is yet unknown, we examined the effects of transient VTA inactivation by direct microinjections of a mixture of the GABA(A) and GABA(B) receptor agonists, muscimol and baclofen. Results reveal that PIT, i.e., the increase in instrumental responding during presentation of a Pavlovian stimulus, was abolished by intra-VTA microinjections of muscimol/baclofen. These data provide the first evidence that the VTA mediates Pavlovian influences on instrumental behavior.     

Measuring affective clarity indirectly: individual differences in response latencies of state

This research investigated a new method to measure momentary affective clarity indirectly, which is based on latencies of responses to state affect items. Three studies revealed that this indirect measure of momentary clarity demonstrated high reliability and stability as well as convergent and predictive validity. The indirect measure was associated with dispositional clarity when the concept of clarity was activated before measuring response latencies (Studies 1 and 2) and was related to self-reports of momentary clarity (Study 3). Furthermore, Study 3 demonstrated that indirectly measured clarity decreased after an affectively complex film. Indirectly, but not directly, measured momentary clarity predicted a more positive affective state at the end of the study. This effect was mediated by affect regulation.     

The Chemnitz LogAnalyzer: A tool for analyzing data from hypertext navigation research

Computer-based studies usually produce log files as raw data. These data cannot be analyzed adequately with conventional statistical software. The Chemnitz LogAnalyzer provides tools for quick and comfortable visualization and analyses of hypertext navigation behavior by individual users and for aggregated data. In addition, it supports analogous analyses of questionnaire data and reanalysis with respect to several predefined orders of nodes of the same hypertext. As an illustration of how to use the Chemnitz LogAnalyzer, we give an account of one study on learning with hypertext. Participants either searched for specific details or read a hypertext document to familiarize themselves with its content. The tool helped identify navigation strategies affected by these two processing goals and provided comparisons, for example, of processing times and visited sites. Altogether, the Chemnitz LogAnalyzer fills the gap between log files as raw data of Web-based studies and conventional statistical software.     

Learning artificial grammars: No evidence for the acquisition of rules

Two experiments investigated whether there is evidence for acquisition of rules in implicit artificial grammar learning (AGL). Two different methods were used in meeting this goal, multiple regression analysis and analysis of receiver-operating characteristics (ROCs). By means of multiple regression analysis, several types of knowledge were identified that were used in judgments of grammaticality, for example, about single letters and about larger stimulus fragments. There was no evidence for the contribution of rule knowledge. The ROCs were in accord with a similarity-based account of AGL and thus did not support the notion that rule knowledge is acquired in AGL either. Simulations with a connectionist model corroborated the conclusion that the results were in accord with a similarity-based, associative account.     

Imitation is beneficial for verb learning in toddlers

The interplay between action and language is still not fully understood in terms of its relevance for early language development. Here, we investigated whether action imitation may be beneficial for first language acquisition. In a word-learning study 24-, 30- and 36-month-old children (N = 96) learned the labels of different actions in one of two conditions: Either the children just observed the experimenter producing the action (observation condition) or children produced the action themselves (action condition). The results show that 36-month-olds learned the labels of the more complex actions in both conditions, whereas 30-month-olds learned the labels only in the action but not in the observation condition. These findings suggest that action imitation is beneficial for verb learning early in life.     

Eye movements reflect and shape strategies in fraction comparison

The comparison of fractions is a difficult task that can often be facilitated by separately comparing components (numerators and denominators) of the fractions—that is, by applying so-called component-based strategies. The usefulness of such strategies depends on the type of fraction pair to be compared. We investigated the temporal organization and the flexibility of strategy deployment in fraction comparison by evaluating sequences of eye movements in 20 young adults. We found that component-based strategies could account for the response times and the overall number of fixations observed for the different fraction pairs. The analysis of eye movement sequences showed that the initial eye movements in a trial were characterized by stereotypical scanning patterns indicative of an exploratory phase that served to establish the kind of fraction pair presented. Eye movements that followed this phase adapted to the particular type of fraction pair and indicated the deployment of specific comparison strategies. These results demonstrate that participants employ eye movements systematically to support strategy use in fraction comparison. Participants showed a remarkable flexibility to adapt to the most efficient strategy on a trial-by-trial basis. Our results confirm the value of eye movement measurements in the exploration of strategic adaptation in complex tasks.     

The Instrumental Role of Personality Traits: Using Mixture Structural Equation Modeling to Investigate Individual Differences in the Relationships Between the Big Five Traits and Life Satisfaction

Adopting a social-cognitive view of personality, this study investigated individual differences in the direct (i.e., temperamental) and indirect (i.e., instrumental) effects of the Big Five traits on life satisfaction. For that purpose, we examined a process model in which domain-based emotional experiences mediated the instrumental effects of personality traits. Using mixture structural equation modeling (n = 2682 adults) we found that the direct effects of neuroticism and extraversion were invariant across individuals, whereas the instrumental effects of the Big Five traits varied across two unobserved subgroups. In one of these subgroups (60 %), conscientiousness, openness, agreeableness, and neuroticism had relatively larger effects on domain-based affect and life satisfaction. In a second subgroup (40 %), extraversion was comparatively more relevant for explaining domain-based affect and life satisfaction. Our findings provide evidence that the instrumental role of personality traits and judgmental processes may act in accord to promote subjective well-being.